NHA EKG Exam Notes
NHA CERTIFIED EKG TECHNICIAN (CET) MASTER STUDY GUIDE
PART 1 – HEART ANATOMY & PHYSIOLOGY ❤
❤ Why This Section Matters
Before you can understand an ECG, you have to understand what the ECG is recording.
An ECG DOES NOT record the heart squeezing.
It records the electrical activity that causes the heart to squeeze.
Exam Tip 🚨
Electrical activity comes FIRST.
Mechanical contraction comes SECOND.
Think:
Electrical Signal ➜ Muscle Contracts ➜ Blood Pumps
Remember this order because NHA loves testing it.
❤ What Is the Heart?
The heart is a muscular pump about the size of your closed fist.
Its job is to continuously pump blood throughout the body.
It beats approximately:
❤ 60–100 times/minute at rest
❤ Around 100,000 beats/day
❤ About 35 million beats/year
❤ Roughly 2.5–3 billion beats in a lifetime
The heart never truly rests.
❤ Functions of the Heart
Know these!
The heart:
✔ Pumps oxygen-rich blood to the body
✔ Pumps oxygen-poor blood to the lungs
✔ Maintains blood pressure
✔ Delivers nutrients
✔ Removes wastes
✔ Carries hormones
✔ Helps regulate body temperature
❤ Location of the Heart
The heart sits in the:
Mediastinum
The mediastinum is the space between the lungs.
It is:
✔ Behind the sternum
✔ Slightly left of midline
✔ Above the diaphragm
✔ Between both lungs
Remember
People often think the heart is completely on the left.
❌ Wrong.
Most of the heart actually sits near the center of the chest.
Only the apex points left.
❤ Apex vs Base
Apex
The pointed bottom tip.
Points:
⬅ Left
⬇ Down
➡ Forward
The apex is where you hear the strongest heartbeat (apical pulse).
Usually found at:
5th intercostal space
Left midclavicular line
Know this!
Base
The broad upper portion.
Contains the major blood vessels entering and leaving the heart.
❤ Heart Layers
The heart has THREE layers.
1. Endocardium
Innermost layer
Smooth lining
Blood touches this layer.
Think:
ENDO = INSIDE
2. Myocardium
Middle layer
Largest layer
Made of cardiac muscle
Responsible for pumping blood.
This is the layer that contracts.
Most heart attacks damage the myocardium.
Think:
MYO = Muscle
3. Epicardium
Outer layer
Protective covering
Also called the visceral pericardium.
Think:
EPI = Upon the outside
❤ Pericardium
The heart sits inside a protective sac called the pericardium.
Functions:
✔ Protects the heart
✔ Holds heart in place
✔ Reduces friction during beating
Contains a small amount of lubricating fluid.
❤ Heart Chambers
The heart has FOUR chambers.
Upper chambers:
RIGHT ATRIUM
LEFT ATRIUM
Lower chambers:
RIGHT VENTRICLE
LEFT VENTRICLE
Memory Trick:
"Atria Are Above"
❤ Right Atrium
Receives oxygen-poor blood from the body.
Blood enters through:
Superior Vena Cava
Inferior Vena Cava
Coronary Sinus
Think:
RIGHT ATRIUM = RECEIVING ROOM
❤ Right Ventricle
Receives blood from right atrium.
Pumps blood to lungs.
Blood exits through:
Pulmonary artery
❤ Left Atrium
Receives oxygen-rich blood from lungs.
Blood enters through:
Pulmonary veins
Remember:
Pulmonary VEINS carry oxygenated blood.
This is a favorite exam question!
❤ Left Ventricle
Largest
Strongest
Most muscular chamber.
Pumps blood through the:
Aorta
Then to the entire body.
Because it pumps to the whole body, it has the thickest wall.
❤ Which Chamber Is Thickest?
⭐ LEFT VENTRICLE ⭐
Why?
Because it pumps blood against the highest pressure to the entire body.
NHA asks this ALL the time.
❤ Septum
The septum is the wall dividing the heart into right and left sides.
Purpose:
Keeps oxygen-rich blood from mixing with oxygen-poor blood.
❤ Four Heart Valves
Valves make sure blood flows in ONE direction.
Think:
"Valves are one-way doors."
Tricuspid Valve
Between:
Right Atrium
Right Ventricle
Memory:
TRI = RIGHT
Pulmonary Valve
Between:
Right ventricle
Pulmonary artery
Mitral (Bicuspid) Valve
Between:
Left atrium
Left ventricle
Memory:
MITRAL = LEFT
Aortic Valve
Between:
Left ventricle
Aorta
❤ Blood Flow Through the Heart
🔥 THIS IS ONE OF THE MOST IMPORTANT THINGS TO MEMORIZE! 🔥
Learn this in order:
Body
↓
Superior & Inferior Vena Cava
↓
Right Atrium
↓
Tricuspid Valve
↓
Right Ventricle
↓
Pulmonary Valve
↓
Pulmonary Artery
↓
Lungs
↓
Pulmonary Veins
↓
Left Atrium
↓
Mitral Valve
↓
Left Ventricle
↓
Aortic Valve
↓
Aorta
↓
Body
Memory Trick
Body → Right → Lungs → Left → Body
If you can say that quickly, you already know the big picture.
❤ Great Vessels
Know these cold:
Aorta → Carries oxygenated blood from the left ventricle to the body.
Superior Vena Cava (SVC) → Returns deoxygenated blood from the upper body to the right atrium.
Inferior Vena Cava (IVC) → Returns deoxygenated blood from the lower body to the right atrium.
Pulmonary Artery → Carries deoxygenated blood from the right ventricle to the lungs. (Exception: It's an artery carrying deoxygenated blood.)
Pulmonary Veins → Carry oxygenated blood from the lungs to the left atrium. (Exception: They're veins carrying oxygenated blood.)
🚨 Exam Trap: Arteries usually carry oxygenated blood and veins usually carry deoxygenated blood—but the pulmonary artery and pulmonary veins are the exceptions because they're traveling to and from the lungs, not the body.
❤ Coronary Circulation
The heart muscle needs its own blood supply.
This comes from the coronary arteries, which branch off the aorta.
If a coronary artery becomes blocked:
⬇ Oxygen delivery to the heart muscle decreases.
⬇ Heart muscle cells begin to die.
➡ This can lead to a myocardial infarction (heart attack).
❤ Coronary Arteries vs. Coronary Veins
• Coronary arteries deliver oxygen-rich blood to the myocardium.
• Coronary veins collect oxygen-poor blood from the myocardium.
• Most coronary veins drain into the coronary sinus, which empties into the right atrium.
❤ Oxygenated vs. Deoxygenated Blood
Oxygenated blood:
• Bright red
• High oxygen
• Leaves the lungs
• Travels to the body
Deoxygenated blood:
• Dark red
• Low oxygen
• Returns from the body
• Travels to the lungs
❤ Quick Comparison Table
Structure Main Job
Right Atrium Receives deoxygenated blood from the body
Right Ventricle Pumps deoxygenated blood to the lungs
Left Atrium Receives oxygenated blood from the lungs
Left Ventricle Pumps oxygenated blood to the body
Aorta Carries oxygenated blood to the body
Vena Cava Returns deoxygenated blood to the heart
Pulmonary Artery Carries deoxygenated blood to the lungs
Pulmonary Veins Carry oxygenated blood to the heart
⭐ MUST MEMORIZE COLD
✔ The heart has 4 chambers.
✔ The left ventricle is the thickest chamber.
✔ The heart has 4 valves.
✔ Blood flows in one direction because of the valves.
✔ The pulmonary artery carries deoxygenated blood.
✔ The pulmonary veins carry oxygenated blood.
✔ The myocardium is the muscular pumping layer.
✔ The heart sits in the mediastinum.
✔ The apex points left, down, and forward.
✔ Blood flow sequence: Body → Right Heart → Lungs → Left Heart → Body
🎯 Self-Quiz (Don't Peek!)
1. What does an ECG measure: electrical activity or mechanical contraction?
2. Which heart chamber has the thickest wall?
3. What is the main job of the myocardium?
4. Which valve is located between the right atrium and right ventricle?
5. Which vessel carries oxygen-rich blood from the lungs to the heart?
6. What are the two exceptions to the "arteries carry oxygenated blood, veins carry deoxygenated blood" rule?
7. Which chamber receives blood from the superior and inferior vena cava?
8. In what part of the chest is the heart located?
9. Name the four heart valves in the order blood passes through them.
10. Trace a drop of blood from the right atrium all the way until it returns to the left atrium.
💡 Abby's Memory Hacks
🫀 "LAB RAT" (blood flow through the valves):
• L = Left Atrium
• A = Aortic Valve
• B = Bicuspid (Mitral) Valve
• R = Right Atrium
• A = Pulmonary Artery
• T = Tricuspid Valve
(You'll still want to know the actual flow, but this helps you remember the valve names.)
🫀 "Right → Respiratory, Left → Large Body"
• Right side pumps blood to the lungs (respiratory system).
• Left side pumps blood to the rest of the body.
🎯 NHA High-Yield Facts
If you only had 5 minutes to review this section before the exam, make sure you know:
• The complete blood flow pathway.
• The four chambers and four valves.
• Which vessels carry oxygenated vs. deoxygenated blood.
• Why the left ventricle is thicker than the right.
• That an ECG records electrical activity, not the actual pumping action.
PART 2 – THE CARDIAC CONDUCTION SYSTEM (Electrical System of the Heart)
❤ Why This Section Matters
Remember from Part 1:
An ECG records the electrical activity of the heart.
So...
Where does that electricity come from?
The heart has its own built-in electrical system.
Unlike most muscles in the body, the heart doesn't need the brain to tell it when to beat.
Instead, it has automaticity, meaning specialized cardiac cells can generate their own electrical impulses.
This allows the heart to continue beating even if communication with the brain is lost (although the rate and rhythm may change).
❤ Four Properties of Cardiac Cells
These are HIGH-YIELD concepts.
1. Automaticity
The ability to create an electrical impulse without outside stimulation.
Example:
The SA node naturally fires on its own.
Think:
AUTO = Does it Automatically
2. Conductivity
The ability to pass an electrical impulse from one cell to another.
Think of electrical wiring in a house.
Electricity moves from one wire to the next.
The heart does the same thing.
3. Excitability (Irritability)
The ability of cardiac cells to respond to an electrical stimulus.
If stimulated...
The cells contract.
4. Contractility
The ability of heart muscle cells to shorten and squeeze after being electrically stimulated.
Remember:
Electrical activity comes first.
Contraction happens second.
❤ The Electrical Pathway
🔥 THIS IS ONE OF THE MOST IMPORTANT THINGS TO MEMORIZE. 🔥
Every heartbeat follows the same pathway.
Say this over and over until you can do it without looking.
SA Node
↓
Atria
↓
AV Node
↓
Bundle of His
↓
Right & Left Bundle Branches
↓
Purkinje Fibers
↓
Ventricles Contract
❤ Step 1 — SA Node
Full Name:
Sinoatrial Node
Nickname:
⭐ The Natural Pacemaker ⭐
Location:
Upper part of the Right Atrium near the opening of the Superior Vena Cava.
Its job:
✔ Starts every heartbeat
✔ Generates the electrical impulse
✔ Determines heart rate
Intrinsic Rate
Without any outside influence...
The SA node fires:
❤ 60–100 beats/minute
This is NORMAL SINUS RHYTHM.
Exam Tip 🚨
If the SA node is working properly...
The ECG should show:
✔ P wave
✔ Normal PR interval
✔ Narrow QRS
✔ Regular rhythm
Memory Trick
SA
Starts
All beats
❤ Step 2 — Atrial Depolarization
After the SA node fires...
The electrical impulse spreads across BOTH atria.
What happens?
The atria contract.
On the ECG:
⭐ This creates the P Wave.
Remember:
P Wave = Atrial Depolarization
NOT contraction.
The contraction happens immediately AFTER depolarization.
❤ Step 3 — AV Node
Full name:
Atrioventricular Node
Location:
Lower Right Atrium near the tricuspid valve.
Its job:
Acts as the gatekeeper of the electrical signal.
Why Does It Delay the Signal?
The AV node briefly slows the electrical impulse.
This pause gives the atria enough time to finish contracting and push blood into the ventricles before the ventricles contract.
Without this delay...
The atria and ventricles would squeeze at nearly the same time, making the heart much less efficient.
Intrinsic Rate
If the SA node fails...
The AV node can become the pacemaker.
Rate:
❤ 40–60 beats/minute
This is called an escape rhythm.
Memory Trick
AV Node
Allows
Ventricles to fill
Exam Tip 🚨
AV node problems can cause:
Heart blocks
You'll study those in the rhythm section.
❤ Step 4 — Bundle of His
Also called:
AV Bundle
Job:
Carries the impulse from the AV node into the interventricular septum.
Think of it as the "bridge" between the atria and ventricles.
Without it...
The impulse can't efficiently travel to the ventricles.
❤ Step 5 — Right & Left Bundle Branches
The Bundle of His divides into:
✔ Right Bundle Branch
✔ Left Bundle Branch
These travel down either side of the interventricular septum.
Purpose:
Carry electricity toward the apex of the heart.
Left Bundle Branch
The left bundle branch divides into two fascicles:
• Left anterior fascicle
• Left posterior fascicle
For the NHA exam, it's usually enough to know that the left bundle branch splits into two major pathways and helps distribute the impulse throughout the left ventricle.
❤ Step 6 — Purkinje Fibers
These are tiny fibers spread throughout the ventricular walls.
Job:
Rapidly distribute the electrical impulse through the ventricles.
Result:
The ventricles contract together in a coordinated, powerful squeeze.
On the ECG:
⭐ Ventricular depolarization creates the QRS Complex.
Intrinsic Rate
If everything above fails...
Purkinje fibers can act as the pacemaker.
Rate:
❤ 20–40 beats/minute
This is usually too slow to maintain adequate blood flow and often requires emergency treatment.
❤ The Electrical System in One Simple Flow
SA Node
⬇
Atria Depolarize
⬇
P Wave
⬇
AV Node Delay
⬇
Bundle of His
⬇
Bundle Branches
⬇
Purkinje Fibers
⬇
QRS Complex
⬇
Ventricles Contract
❤ Pacemaker Hierarchy
Structure Intrinsic Rate Primary Job
SA Node 60–100 bpm Starts each heartbeat
AV Node 40–60 bpm Delays the impulse; backup pacemaker
Purkinje Fibers (Ventricular Pacemakers) 20–40 bpm Spread impulse through ventricles; last-resort pacemaker
Exam Tip 🚨: The fastest pacemaker usually controls the heart because it fires before the slower ones can.
❤ Why the SA Node Wins
Normally...
The SA node fires first.
Because it fires faster than every other pacemaker...
It suppresses the slower pacemakers.
This is called overdrive suppression.
Think:
Fastest pacemaker wins.
❤ What Happens If the SA Node Fails?
If the SA node stops firing...
The AV node takes over.
Heart rate becomes:
40–60 bpm
If BOTH fail...
Purkinje fibers take over.
Heart rate:
20–40 bpm
❤ Mechanical vs Electrical Activity
This is tested A LOT.
Electrical activity:
What the ECG records.
Mechanical activity:
Actual squeezing of the heart.
Electrical activity ALWAYS happens first.
❤ Blood Flow vs Electrical Flow
Don't confuse them!
Electrical Flow:
SA Node
↓
AV Node
↓
Bundle of His
↓
Bundle Branches
↓
Purkinje Fibers
Blood Flow:
Body
↓
Right Heart
↓
Lungs
↓
Left Heart
↓
Body
These are TWO completely different pathways.
❤ Why the AV Delay Is So Important
Imagine trying to pour water into a bottle while someone is squeezing the bottle shut.
It wouldn't work very well.
The AV node delay gives the ventricles time to fill before they contract, making each heartbeat much more effective.
❤ Clinical Correlations (Know the Basics)
• SA node dysfunction can lead to slow heart rates (sinus bradycardia or sick sinus syndrome).
• AV node problems can cause heart blocks.
• Bundle branch blocks slow electrical conduction through one ventricle, causing a wider QRS complex.
• Damage to the Purkinje system can lead to dangerous ventricular rhythms.
You don't need to know every detail for the NHA exam, but you should recognize these associations.
❤ Quick Review Table
Structure Function ECG Association
SA Node Starts impulse Beginning of P wave
Atria Depolarize and prepare to contract P wave
AV Node Delays impulse PR interval
Bundle of His Conducts impulse to ventricles Between PR and QRS
Bundle Branches Carry impulse down septum Beginning of ventricular activation
Purkinje Fibers Spread impulse through ventricles QRS complex
🚨 NHA EXAM TRAPS
❌ "The AV node is the heart's natural pacemaker."
➡ FALSE.
The SA node is the natural pacemaker.
❌ "The ECG records ventricular contraction."
➡ FALSE.
It records ventricular depolarization, which triggers contraction.
❌ "The AV node speeds up the electrical impulse."
➡ FALSE.
The AV node slows the impulse.
❌ "Purkinje fibers normally determine heart rate."
➡ FALSE.
The SA node normally sets the heart rate.
⭐ MUST MEMORIZE COLD
✔ SA Node = Natural pacemaker
✔ SA Node = 60–100 bpm
✔ AV Node = 40–60 bpm
✔ Purkinje Fibers = 20–40 bpm
✔ P wave = Atrial depolarization
✔ QRS = Ventricular depolarization
✔ Electrical activity ALWAYS comes before contraction
✔ AV node delays the impulse so ventricles can fill
✔ Fastest pacemaker controls the heart
✔ Electrical pathway: SA Node → Atria → AV Node → Bundle of His → Right & Left Bundle Branches → Purkinje Fibers → Ventricles
🧠 Self-Quiz (No Peeking!)
1. What is the heart's natural pacemaker?
2. What is the normal intrinsic firing rate of the SA node?
3. Why does the AV node delay the electrical impulse?
4. What ECG wave represents atrial depolarization?
5. What ECG complex represents ventricular depolarization?
6. If the SA node fails, which structure usually becomes the pacemaker?
7. What is the intrinsic rate of the AV node?
8. What is the intrinsic rate of the Purkinje fibers?
9. Which part of the conduction system acts as the "bridge" between the atria and ventricles?
10. Put these in the correct order:
• Purkinje Fibers
• AV Node
• SA Node
• Bundle Branches
• Bundle of His
💡 Abby's Memory Hacks
❤ "SA Starts, AV Allows, Purkinje Pushes"
• SA = Starts the heartbeat
• AV = Allows the ventricles to fill (by delaying the impulse)
• Purkinje = Pushes the impulse through the ventricles
❤ Pacemaker Rates: 60–40–20 Rule
• SA Node = 60–100
• AV Node = 40–60
• Purkinje = 20–40
Just remember: 60 → 40 → 20. The farther down the conduction system you go, the slower the backup pacemaker rate.
🎯 NHA High-Yield Facts
Before moving on, you should be able to answer these instantly:
• What is the heart's natural pacemaker?
• What does the P wave represent?
• What does the QRS complex represent?
• What is the conduction pathway in order?
• Why is the AV node delay necessary?
• What are the intrinsic rates of the SA node, AV node, and Purkinje fibers?
PART 3 – ECG BASICS (How to Read an ECG Strip)
❤ Why This Section Matters
Now that you understand:
✅ How the heart is built
✅ How electricity travels through the heart
It's time to learn how an ECG machine records that electricity.
Think of the ECG machine like a microphone.
It doesn't create electricity.
It simply detects the tiny electrical signals produced by the heart and records them on graph paper.
Exam Tip 🚨
An ECG does NOT:
❌ Measure blood pressure
❌ Measure how much blood the heart pumps
❌ Measure oxygen levels
❌ Directly measure contraction
It ONLY records the electrical activity of the heart.
❤ What Does ECG Mean?
ECG = Electrocardiogram
(EKG is simply the German abbreviation "Elektrokardiogramm." In the U.S., ECG and EKG mean the exact same thing.)
❤ Purpose of an ECG
Doctors order ECGs to:
✔ Detect abnormal heart rhythms (arrhythmias)
✔ Detect heart attacks (myocardial infarction)
✔ Evaluate chest pain
✔ Investigate dizziness or fainting
✔ Monitor medication effects
✔ Monitor pacemakers
✔ Check electrolyte imbalances
✔ Assess before surgery
✔ Evaluate heart disease
❤ What Is Being Recorded?
Remember this sequence:
Electrical impulse
↓
Heart muscle depolarizes
↓
Heart muscle contracts
↓
Blood is pumped
The ECG only records the electrical impulse.
❤ Depolarization
⭐ One of the MOST IMPORTANT WORDS on the exam.
Depolarization is the electrical activation of cardiac muscle.
After depolarization...
The muscle contracts.
Think:
Depolarization = TURNING THE HEART ON
Example
SA Node fires
↓
Atria depolarize
↓
Atria contract
❤ Repolarization
After the muscle contracts...
It must electrically reset before the next beat.
This is called:
⭐ Repolarization
Think:
RESET BUTTON
Without repolarization...
The heart couldn't beat again.
❤ Polarization
Polarization means the heart cell is at resting electrical state, ready for the next impulse.
Think of it like a charged battery waiting to be used.
❤ ECG Graph Paper
The ECG is printed on special graph paper.
It contains:
Tiny boxes
Large boxes
Horizontal measurements
Vertical measurements
You MUST know what these mean.
❤ Small Boxes
Each small box equals:
⏱ 0.04 seconds
Width = Time
Height = Voltage (electrical strength)
There are 5 small boxes inside every large box.
❤ Large Boxes
Each large box equals:
⏱ 0.20 seconds
Five large boxes equal:
⏱ 1 second
❤ Time Cheat Sheet
Boxes Time
1 Small Box 0.04 sec
5 Small Boxes 0.20 sec
1 Large Box 0.20 sec
5 Large Boxes 1 second
30 Large Boxes 6 seconds
🚨 MEMORIZE THIS TABLE!
❤ Paper Speed
The ECG paper moves at:
⭐ 25 mm/second
This is the STANDARD speed for the NHA exam.
Some hospitals may occasionally use 50 mm/sec, but unless a question specifically says otherwise, assume 25 mm/sec.
❤ Calibration
Every ECG begins with a small calibration mark.
Standard calibration:
10 mm = 1 millivolt (mV)
This tells you the ECG machine is recording correctly.
❤ Voltage
The vertical direction on the ECG measures:
Electrical strength
Measured in:
Millivolts (mV)
The taller the wave...
The stronger the electrical signal detected in that lead.
❤ Time vs Voltage
Horizontal Direction
↓
Measures TIME
Vertical Direction
↓
Measures VOLTAGE
🚨 This is a favorite exam question.
❤ The ECG Grid
Think of the ECG paper as two rulers:
Horizontal ruler = TIME
Vertical ruler = ELECTRICITY
Never confuse them.
❤ Why Are There Different Waves?
Each wave represents a different electrical event.
The ECG separates them so we can see what each part of the heart is doing.
We'll learn every wave in the next section.
For now:
P Wave
↓
QRS Complex
↓
T Wave
❤ Normal Heartbeat Sequence
SA Node Fires
↓
P Wave
↓
AV Delay
↓
QRS Complex
↓
T Wave
↓
Repeat
❤ Why ECGs Have Different Leads
The heart is three-dimensional.
Looking from only one angle would miss important information.
So we record electrical activity from multiple directions.
Think of it like taking pictures of a car:
Front
Back
Side
Top
Each picture shows something different.
❤ Standard 12-Lead ECG
A standard ECG uses:
⭐ 10 electrodes
To create:
⭐ 12 different views (leads)
🚨 Exam Trap: Many students think a 12-lead ECG uses 12 electrodes. It uses 10 electrodes to generate 12 leads.
❤ The 10 Electrodes
4 Limb Electrodes:
• Right Arm (RA)
• Left Arm (LA)
• Right Leg (RL)
• Left Leg (LL)
6 Chest (Precordial) Electrodes:
• V1
• V2
• V3
• V4
• V5
• V6
You'll master exact placement in Part 5.
❤ Limb Leads vs Chest Leads
Limb Leads
• View the heart in the frontal plane.
• Includes Leads I, II, III, aVR, aVL, and aVF.
Chest (Precordial) Leads
• View the heart in the horizontal plane.
• Includes V1 through V6.
For the NHA exam, know that each lead looks at the heart from a different angle.
❤ Artifact
An artifact is anything that interferes with the ECG tracing but is NOT caused by the heart's electrical activity.
Examples:
• Patient movement
• Muscle tremor
• Loose electrodes
• Electrical interference
• Poor skin preparation
We'll cover troubleshooting in detail later.
❤ ECG Accuracy
An ECG is only as good as:
✔ Proper lead placement
✔ Clean skin
✔ Good electrode contact
✔ Minimal patient movement
✔ Proper machine calibration
Poor technique can create a tracing that looks abnormal even when the heart is normal.
❤ Common Reasons for an ECG
Patients with:
Chest pain
Shortness of breath
Palpitations
Fainting
Dizziness
Heart disease
Medication monitoring
Routine physicals
Pre-operative evaluations
❤ ECG Limitations
An ECG is extremely useful, but it doesn't tell us everything.
It cannot:
❌ Measure blood flow directly
❌ Show blocked arteries by itself
❌ Diagnose every heart problem
❌ Replace an echocardiogram or stress test
It must always be interpreted along with the patient's symptoms and clinical history.
❤ Clinical Correlations
An ECG can help detect:
• Arrhythmias
• Acute or previous myocardial infarctions
• Conduction abnormalities
• Chamber enlargement
• Electrolyte disturbances (such as high or low potassium)
• Effects of certain medications
Remember: the ECG provides clues—it is one piece of the overall clinical picture.
❤ Quick Review Table
Term Meaning
ECG/EKG Recording of the heart's electrical activity
Depolarization Electrical activation before contraction
Repolarization Electrical recovery/reset
Polarization Resting electrical state
Small Box 0.04 seconds
Large Box 0.20 seconds
5 Large Boxes 1 second
30 Large Boxes 6 seconds
Standard Paper Speed 25 mm/sec
Standard Calibration 10 mm = 1 mV
Horizontal Axis Time
Vertical Axis Voltage
🚨 NHA EXAM TRAPS
❌ "An ECG records heart muscle contraction."
➡ FALSE.
It records electrical activity.
❌ "A 12-lead ECG uses 12 electrodes."
➡ FALSE.
It uses 10 electrodes.
❌ "The vertical axis measures time."
➡ FALSE.
The vertical axis measures voltage.
❌ "One large box equals 1 second."
➡ FALSE.
One large box = 0.20 seconds.
Five large boxes = 1 second.
❌ "Artifacts always mean the patient has a heart problem."
➡ FALSE.
Artifacts are often caused by movement, poor electrode contact, or outside interference.
⭐ MUST MEMORIZE COLD
✔ ECG = Electrical activity only
✔ Depolarization = Electrical activation
✔ Repolarization = Electrical recovery
✔ Polarization = Resting state
✔ Small box = 0.04 sec
✔ Large box = 0.20 sec
✔ 5 large boxes = 1 second
✔ 30 large boxes = 6 seconds
✔ Paper speed = 25 mm/sec
✔ Calibration = 10 mm = 1 mV
✔ Standard 12-lead ECG = 10 electrodes
🧠 Self-Quiz (No Peeking!)
1. What does an ECG measure?
2. What is the difference between depolarization and repolarization?
3. How many seconds does one small box represent?
4. How many seconds does one large box represent?
5. What is the standard ECG paper speed?
6. What does the horizontal axis measure?
7. What does the vertical axis measure?
8. How many electrodes are used for a standard 12-lead ECG?
9. Give three examples of ECG artifact.
10. Why does an ECG use multiple leads instead of just one?
💡 Abby's Memory Hacks
❤ "H = Horizontal = Hours (Time)"
• Horizontal = Time
• Vertical = Voltage
❤ "4–20 Rule"
• 0.04 sec = 1 small box
• 0.20 sec = 1 large box
❤ "10 Makes 12"
• 10 electrodes create 12 leads.
🎯 NHA High-Yield Facts
If you can answer these instantly, you're in great shape:
• What does an ECG actually record?
• What are depolarization and repolarization?
• How many seconds are in a small box and a large box?
• What is the standard paper speed?
• How many electrodes are used for a standard 12-lead ECG?
• What do the horizontal and vertical axes represent?
PART 4 – ECG WAVES, SEGMENTS & INTERVALS (The Language of the ECG)
❤ Why This Section Matters
If the ECG strip were a sentence...
The:
• P Wave
• PR Interval
• QRS Complex
• ST Segment
• T Wave
...would be the words.
If you understand what each one means...
You can understand what the heart is trying to tell you.
🚨 NHA Reality Check: This is one of the MOST TESTED topics on the exam.
❤ One Complete Heartbeat
A normal heartbeat follows this order:
SA Node Fires
↓
P Wave
↓
PR Segment
↓
PR Interval
↓
QRS Complex
↓
ST Segment
↓
T Wave
↓
(U Wave sometimes)
↓
Next Beat
Think of this as the "story" of one heartbeat.
❤ P WAVE
What does it represent?
⭐ Atrial Depolarization
Remember:
Depolarization = Electrical activation
NOT contraction.
The atria contract immediately AFTER they depolarize.
Where does it start?
The SA Node
The electrical impulse spreads across both atria.
Normal Appearance
✔ Small
✔ Rounded
✔ Smooth
✔ One P wave before every QRS
Normal Duration
⭐ Less than 0.12 seconds
(That's fewer than 3 small boxes.)
Normal Height
Less than 2.5 mm
If the P Wave Is Missing...
Possible causes include:
• Atrial fibrillation
• Junctional rhythms
• Ventricular rhythms
• Sinus arrest
(You'll learn these rhythms later.)
If the P Wave Looks Different...
It may suggest:
• Enlarged atria
• An abnormal atrial rhythm
• The impulse is starting somewhere other than the SA node
❤ PR SEGMENT
The PR segment is the flat line:
Between:
End of P Wave
↓
Beginning of QRS
What is happening?
The electrical impulse is traveling through:
✔ AV Node
✔ Bundle of His
✔ Bundle Branches
This is where the AV node delay occurs.
Why Is It Important?
The pause allows the ventricles to fill with blood before they contract.
Without it...
The heart wouldn't pump efficiently.
❤ PR INTERVAL
One of the MOST IMPORTANT measurements.
The PR Interval measures:
Beginning of P Wave
↓
Beginning of QRS
What does it represent?
The time it takes the electrical impulse to travel:
SA Node
↓
Atria
↓
AV Node
↓
Bundle of His
↓
Before ventricular depolarization begins
Normal PR Interval
⭐ 0.12–0.20 seconds
Equivalent to:
3–5 small boxes
🚨 MEMORIZE THIS.
PR Interval Too Long
Greater than 0.20 sec
May suggest:
⭐ First-Degree AV Block
PR Interval Too Short
Less than 0.12 sec
May suggest:
• An accessory pathway (such as Wolff-Parkinson-White syndrome)
• Junctional rhythms
For the NHA exam, know that a short PR interval means the impulse reached the ventricles faster than expected.
❤ QRS COMPLEX
The BIG spike.
This is the easiest wave to recognize.
What does it represent?
⭐ Ventricular Depolarization
Remember:
Electrical activation of the ventricles.
NOT contraction.
The ventricles contract immediately afterward.
Why Is It Bigger Than the P Wave?
The ventricles contain much more muscle than the atria.
More muscle
↓
More electricity
↓
Larger wave
Normal Duration
⭐ Less than 0.12 seconds
Usually 0.06–0.10 seconds
Equivalent to:
Less than 3 small boxes
Wide QRS
Greater than 0.12 sec
May indicate:
• Bundle Branch Block
• Ventricular rhythm
• Ventricular pacing
• Hyperkalemia (high potassium)
Narrow QRS
Usually means the impulse traveled through the normal conduction system.
❤ Q WAVE
Small downward deflection BEFORE the R wave.
A small Q wave can be normal.
A large or deep Q wave may suggest:
Previous myocardial infarction (old heart attack).
❤ R WAVE
First positive (upward) deflection.
Usually the tallest part of the ECG.
Represents ventricular depolarization.
❤ S WAVE
Negative (downward) deflection AFTER the R wave.
Still part of ventricular depolarization.
❤ ST SEGMENT
The flat line:
End of QRS
↓
Beginning of T Wave
What does it represent?
The ventricles are fully depolarized and beginning the process that leads into repolarization.
Normally it should be:
⭐ Flat (isoelectric)
ST Elevation
Can suggest:
⭐ Acute Myocardial Infarction (STEMI)
This is a medical emergency.
ST Depression
Can suggest:
• Myocardial ischemia (reduced blood flow)
• Certain medication effects
• Other cardiac conditions
For the NHA exam, know that ST depression may indicate the heart muscle isn't getting enough oxygen.
❤ T WAVE
Represents:
⭐ Ventricular Repolarization
Remember:
The ventricles are electrically resetting.
This allows the next heartbeat to occur.
Normal Appearance
✔ Rounded
✔ Smooth
✔ Upright in most leads
Tall T Waves
Can suggest:
Hyperkalemia
(High potassium)
Flat T Waves
Can suggest:
Hypokalemia
(Low potassium)
Inverted T Waves
May suggest:
• Ischemia
• Previous heart injury
• Other cardiac abnormalities
❤ QT INTERVAL
Measures:
Beginning of QRS
↓
End of T Wave
What does it represent?
The total time required for:
Ventricular depolarization
•
Ventricular repolarization
Normal QT
Varies with heart rate.
A commonly used guideline:
Less than half of the R-R interval.
For the NHA exam, you mainly need to know that the QT interval changes with heart rate and can be corrected (QTc).
Prolonged QT
Can increase the risk of dangerous ventricular arrhythmias, including Torsades de Pointes.
Common causes include:
• Certain medications
• Low potassium
• Low magnesium
• Congenital long QT syndrome
❤ U WAVE
Sometimes seen after the T wave.
Usually:
Small
Positive
Not always present.
Prominent U Wave
Most commonly associated with:
⭐ Hypokalemia
(Low potassium)
❤ Putting It All Together
SA Node Fires
↓
P Wave
(Atrial Depolarization)
↓
PR Interval
(Impulse travels through atria and AV node)
↓
QRS Complex
(Ventricular Depolarization)
↓
ST Segment
(Ventricles remain electrically activated)
↓
T Wave
(Ventricular Repolarization)
↓
Next Beat
❤ Quick Review Table
ECG Part Represents Normal Value
P Wave Atrial depolarization < 0.12 sec
PR Interval Atrial to ventricular conduction 0.12–0.20 sec
QRS Complex Ventricular depolarization < 0.12 sec
ST Segment Early ventricular recovery Isoelectric (flat)
T Wave Ventricular repolarization Upright in most leads
QT Interval Total ventricular electrical activity Varies with HR
U Wave Late repolarization (sometimes seen) Usually absent or very small
🚨 NHA EXAM TRAPS
❌ "The P wave represents atrial contraction."
➡ FALSE.
It represents atrial depolarization.
❌ "The QRS complex represents ventricular contraction."
➡ FALSE.
It represents ventricular depolarization.
❌ "The T wave represents atrial repolarization."
➡ FALSE.
It represents ventricular repolarization.
Atrial repolarization does occur, but it's hidden within the QRS complex and cannot normally be seen on the ECG.
❌ "The normal PR interval is less than 0.10 seconds."
➡ FALSE.
Normal = 0.12–0.20 seconds
❌ "The normal QRS duration is 0.18 seconds."
➡ FALSE.
Normal = Less than 0.12 seconds
⭐ MUST MEMORIZE COLD
✔ P Wave = Atrial depolarization
✔ PR Interval = 0.12–0.20 sec
✔ QRS = Ventricular depolarization
✔ QRS duration = < 0.12 sec
✔ ST Segment = Normally flat
✔ T Wave = Ventricular repolarization
✔ Tall T Waves = Hyperkalemia
✔ U Waves = Hypokalemia
✔ ST Elevation = Possible acute MI (STEMI)
✔ Wide QRS = Conduction through the ventricles is delayed
🧠 Self-Quiz (No Peeking!)
1. What does the P wave represent?
2. What is the normal duration of the P wave?
3. What is the normal PR interval?
4. What does the PR interval measure?
5. What does the QRS complex represent?
6. What is the normal QRS duration?
7. What does the T wave represent?
8. Which ECG segment is normally flat?
9. Which electrolyte imbalance is associated with tall, peaked T waves?
10. Which electrolyte imbalance is commonly associated with prominent U waves?
11. What does the QT interval represent?
12. Why can't you normally see atrial repolarization on an ECG?
💡 Abby's Memory Hacks
❤ "P = People Upstairs"
• P wave = Atria (the upper chambers) depolarize.
❤ "QRS = Quick Really Strong Squeeze"
• The large QRS complex is associated with the ventricles, the heart's strongest pumping chambers.
❤ "T = Time to Reset"
• T wave = Ventricular repolarization.
❤ Normal Numbers Song 🎵
• P Wave: < 0.12
• PR Interval: 0.12–0.20
• QRS: < 0.12
Repeat it until you can say it without thinking.
🎯 NHA High-Yield Facts
Before moving on, you should know these instantly:
• P wave = Atrial depolarization
• PR interval = 0.12–0.20 seconds
• QRS = Ventricular depolarization
• QRS duration = Less than 0.12 seconds
• T wave = Ventricular repolarization
• ST segment should be flat
• ST elevation may indicate an acute myocardial infarction
• Tall T waves = Hyperkalemia
• Prominent U waves = Hypokalemia
PART 5 – ECG ELECTRODE & LEAD PLACEMENT (THE #1 HANDS-ON SKILL)
❤ Why This Section Matters
An ECG machine can only be as accurate as the person placing the electrodes.
A perfect machine + wrong placement = WRONG ECG.
A technician must know:
✅ Where each electrode goes ✅ Why it goes there ✅ How placement affects the tracing ✅ How to prepare the patient ✅ How to fix errors
🚨 NHA LOVES THIS TOPIC.
Expect questions about:
• V1–V6 placement
• Limb electrodes
• Patient positioning
• Skin preparation
• Electrode errors
• Artifact caused by poor technique
❤ ECG Terminology: Electrode vs Lead
This is a BIG exam trap.
Electrode
An electrode is the physical sticker placed on the patient's skin.
Example:
V1 sticker
RA sticker
LA sticker
Lead
A lead is the view of the heart's electrical activity.
A lead is NOT a sticker.
Think:
Electrodes = Cameras
Leads = Pictures taken by those cameras
🚨 EXAM TRAP
A:
❌ 12-electrode ECG
does not exist.
A standard:
✅ 12-lead ECG
uses:
⭐ 10 electrodes
to create:
⭐ 12 electrical views
❤ The 10 Electrodes
A standard 12-lead ECG uses:
Four Limb Electrodes
1. Right Arm (RA)
2. Left Arm (LA)
3. Right Leg (RL)
4. Left Leg (LL)
Six Chest Electrodes
1. V1
2. V2
3. V3
4. V4
5. V5
6. V6
❤ Limb Electrode Placement
These electrodes look at the heart from the:
⭐ Frontal plane
Think:
"Looking at the heart from the front."
🟥 RA — Right Arm
Placement:
Right arm
Usually:
• Inner wrist OR
• Upper arm/shoulder area
🟨 LA — Left Arm
Placement:
Left arm
Usually:
• Inner wrist OR
• Upper arm/shoulder area
🟩 RL — Right Leg
Placement:
Right lower leg
Purpose:
⭐ Ground electrode
The RL electrode helps reduce electrical interference.
🟩 LL — Left Leg
Placement:
Left lower leg
Provides:
A view of electrical activity from below the heart.
🚨 IMPORTANT
The limb electrodes do NOT have to be exactly on the wrists and ankles.
They can be placed:
• Arms
• Shoulders
• Legs
• Hips
as long as they are placed correctly and consistently.
❤ Limb Lead Groups
The four limb electrodes create:
Bipolar Limb Leads
These compare electrical differences between two electrodes.
They are:
Lead I
Lead II
Lead III
Augmented Limb Leads
These use one positive electrode compared with a combination of the others.
They are:
aVR
aVL
aVF
❤ Remember:
The 6 limb leads are:
⭐ I, II, III, aVR, aVL, aVF
Together they provide:
6 views of the heart
❤ Chest Leads (Precordial Leads)
These are:
V1–V6
They look at the heart from:
⭐ Horizontal plane
They are especially important for viewing:
• Ventricles
• Septum
• Anterior heart
❤ V1 Placement
⭐ THE MOST TESTED CHEST LEAD
Location:
4th intercostal space
RIGHT side of sternum
Memory:
V1 = 1 is on the right
❤ V2 Placement
Location:
4th intercostal space
LEFT side of sternum
Memory:
V1 and V2 are twins.
Both are:
4th intercostal space
Both sit near the sternum.
❤ V3 Placement
Location:
Between V2 and V4
Memory:
V3 lives in the middle.
❤ V4 Placement
Location:
5th intercostal space
Left midclavicular line
Memory:
V4 = 5th space
❤ V5 Placement
Location:
Same horizontal level as V4
Left anterior axillary line
❤ V6 Placement
Location:
Same horizontal level as V4 and V5
Left midaxillary line
❤ Chest Lead Placement Table
Lead Location
V1 4th intercostal space, right of sternum
V2 4th intercostal space, left of sternum
V3 Between V2 and V4
V4 5th intercostal space, left midclavicular line
V5 Same level as V4, left anterior axillary line
V6 Same level as V4/V5, left midaxillary line
🚨 NHA MEMORY HACK
Remember:
"V1 and V2 are 4"
V1: 4th intercostal space, right
V2: 4th intercostal space, left
"V4 is the door"
V4 is your landmark.
Find:
5th intercostal space
Left midclavicular line
Then:
V5 and V6 follow the same horizontal line.
❤ Finding Intercostal Spaces
The spaces between ribs are called:
⭐ Intercostal spaces
To find the 4th intercostal space:
1. Find the sternal angle (Angle of Louis)
2. Locate the 2nd rib
3. Count downward
❤ Patient Positioning
Standard ECG position:
⭐ Supine (lying flat on the back)
Patient should be:
✔ Relaxed
✔ Still
✔ Comfortable
✔ Warm
❤ Why Supine?
Because movement can create artifact.
The goal:
Reduce anything that interferes with the electrical signal.
❤ Patient Preparation
Before applying electrodes:
1. Explain the procedure
Tell the patient:
• It is painless
• Electrodes will be placed on chest and limbs
• They need to remain still
2. Provide Privacy
Especially when placing chest electrodes.
Use:
• Drapes
• Gowns
• Proper communication
3. Expose Placement Areas
Chest must be accessible.
Respect patient dignity.
4. Clean Skin
Skin should be:
✔ Clean
✔ Dry
✔ Free of oils and lotions
5. Remove Excess Hair if Needed
Hair can prevent electrode contact.
Do NOT shave automatically.
Only remove what interferes.
❤ Skin Preparation
Proper skin prep:
✔ Improves electrode adhesion
✔ Reduces artifact
✔ Improves signal quality
May include:
• Cleaning with alcohol
• Light abrasion
• Removing oils
• Drying skin completely
❤ Special Patient Considerations
❤ Female Patients
Important:
Respect privacy.
Place electrodes correctly.
Do NOT place electrodes over breast tissue if avoidable.
Move breast tissue respectfully if needed.
❤ Pacemaker Patients
You can perform an ECG.
Avoid placing electrodes directly over the pacemaker site if possible.
❤ Amputees
Place electrodes on available limbs.
Follow facility policy.
❤ Tremors/Parkinson's Disease
May create:
Somatic tremor artifact
Try:
• Supporting limbs
• Keeping patient warm
• Reducing movement
❤ Pregnant Patients
ECGs can safely be performed.
Positioning may need adjustment for comfort.
❤ Common Lead Placement Errors
These are VERY important.
❌ V1 and V2 Too High
One of the most common mistakes.
Can cause:
• Abnormal-looking ECG
• False ST changes
• Incorrect interpretation
❌ V4-V6 Not Level
V4, V5, and V6 should line up horizontally.
❌ Limb Leads Reversed
Example:
RA and LA swapped.
Can cause:
• Incorrect lead I
• Abnormal axis appearance
❤ Electrode Removal
After ECG:
✔ Remove electrodes gently
✔ Clean patient if needed
✔ Help patient redress
✔ Dispose properly
✔ Document if required
❤ Quick Review Table
Electrode Location
RA Right arm
LA Left arm
RL Right leg (ground)
LL Left leg
V1 4th ICS right sternum
V2 4th ICS left sternum
V3 Between V2 and V4
V4 5th ICS left midclavicular
V5 Left anterior axillary
V6 Left midaxillary
🚨 NHA EXAM TRAPS
❌ "V1 goes on the left side of the sternum."
FALSE.
V1 = RIGHT side.
❌ "The RL electrode measures a cardiac lead."
FALSE.
RL is the ground electrode.
❌ "A lead and electrode are the same thing."
FALSE.
Electrode = sticker.
Lead = electrical view.
❌ "V5 and V6 should be placed higher than V4."
FALSE.
They should be on the SAME horizontal level.
❌ "A patient must be standing for an ECG."
FALSE.
Standard position is supine.
⭐ MUST MEMORIZE COLD
🔥 12-lead ECG = 10 electrodes
🔥 Electrode = sticker
🔥 Lead = view
🔥 RL = ground
🔥 V1 = 4th intercostal space RIGHT sternum
🔥 V2 = 4th intercostal space LEFT sternum
🔥 V3 = between V2 and V4
🔥 V4 = 5th intercostal space LEFT midclavicular line
🔥 V5 = left anterior axillary line
🔥 V6 = left midaxillary line
🔥 V4, V5, V6 must be horizontal
🔥 Supine = standard ECG position
🧠 Self-Quiz (No Peeking!)
1. How many electrodes create a standard 12-lead ECG?
2. What is the difference between a lead and an electrode?
3. Which electrode is the ground?
4. Where is V1 placed?
5. Where is V2 placed?
6. Where is V4 placed?
7. Where is V6 placed?
8. Why must V4, V5, and V6 be level?
9. What position is the patient usually placed in for a resting ECG?
10. What can poor electrode placement cause?
💡 Abby's Memory Hacks
❤ "Right 1, Left 2"
• V1 = Right sternum
• V2 = Left sternum
❤ "V3 is Between"
• V3 goes between V2 and V4
❤ "V4 Finds the Door"
• V4 is your landmark.
• V5 and V6 follow it.
❤ "Right Leg Rests"
• RL = Resting/ground electrode
🎯 NHA High-Yield Facts
If you know nothing else, know:
1. V1 location
2. V2 location
3. V4 location
4. 10 electrodes = 12 leads
5. Electrode ≠ lead
6. Supine position
7. Proper skin prep prevents artifact
PART 6 – PATIENT CARE, SAFETY, INFECTION CONTROL & PROFESSIONALISM
❤ Why This Section Matters
An EKG technician is not just someone who places stickers on a patient.
You are responsible for:
✅ Patient safety ✅ Accurate identification ✅ Privacy ✅ Infection prevention ✅ Communication ✅ Proper documentation ✅ Recognizing emergencies ✅ Knowing your scope of practice
❤ The EKG Technician’s Role
An EKG technician may:
✔ Prepare patients for ECG testing
✔ Explain the procedure
✔ Apply electrodes
✔ Obtain ECG tracings
✔ Recognize artifacts
✔ Maintain equipment
✔ Perform basic rhythm recognition
✔ Document results
✔ Report abnormal findings
🚨 Scope of Practice
Scope of practice means:
What a healthcare worker is legally allowed to do based on training, certification, and employer policies.
An EKG technician:
✅ CAN:
• Perform an ECG
• Prepare patients
• Obtain vital signs (if trained)
• Recognize abnormalities
• Notify appropriate healthcare providers
An EKG technician:
❌ CANNOT:
• Diagnose a patient
• Tell a patient they are having a heart attack
• Interpret ECG results as a physician
• Prescribe treatment
• Give medical advice outside training
🚨 EXAM TRAP
Patient asks:
"Does this ECG mean I’m having a heart attack?"
Wrong response:
❌ "Yes, your ECG looks bad."
Correct response:
✅ "The healthcare provider will review your ECG results and discuss them with you."
❤ Patient Identification
Before performing ANY procedure:
You MUST identify the patient.
Use:
⭐ Two identifiers
Examples:
1. Patient name
2. Date of birth
OR
1. Name
2. Medical record number
🚨 Never use:
❌ Room number
❌ Bed number
❌ Diagnosis
❌ Appearance
❤ Why Two Identifiers?
Because mistakes happen.
Two identifiers prevent:
• Wrong patient testing
• Wrong documentation
• Wrong treatment
❤ Patient Communication
A good EKG technician:
✔ Introduces themselves
✔ Explains the procedure
✔ Answers questions within scope
✔ Maintains professionalism
✔ Protects privacy
❤ Before the ECG
The technician should:
1. Verify the order
2. Identify the patient
3. Explain procedure
4. Obtain cooperation/consent
5. Provide privacy
6. Position patient correctly
7. Prepare skin
8. Apply electrodes
❤ Consent
Consent means the patient agrees to the procedure.
Before an ECG:
The patient should understand:
• What will happen
• Why it is being done
• That electrodes will be placed on skin
❤ Types of Consent
Express Consent
The patient clearly agrees.
Example:
Patient says:
"Yes, I understand."
Implied Consent
The patient’s actions show agreement.
Example:
Patient rolls up sleeve after explanation.
Informed Consent
The patient understands:
• Procedure
• Risks
• Benefits
• Alternatives
🚨 EKG Technician Reminder
You do NOT force a patient.
If a patient refuses:
✔ Respect refusal
✔ Notify appropriate healthcare provider
✔ Document refusal
❤ HIPAA (VERY IMPORTANT)
HIPAA:
Health Insurance Portability and Accountability Act
Purpose:
Protect patient health information.
❤ Protected Health Information (PHI)
PHI includes:
• Name
• Address
• Phone number
• Medical record number
• Diagnosis
• Test results
• Treatment information
❤ HIPAA Rules for EKG Techs
You MUST:
✅ Keep information private
✅ Discuss patients only with authorized personnel
✅ Secure paperwork
✅ Avoid talking about patients in public areas
🚨 HIPAA Examples
Wrong:
❌ Talking about a patient's ECG results in an elevator.
Wrong:
❌ Leaving ECG printouts on a desk.
Wrong:
❌ Posting patient information online.
Correct:
✅ Discuss information only with healthcare team members involved in care.
❤ OSHA
OSHA:
Occupational Safety and Health Administration
Purpose:
Protect workers from workplace hazards.
OSHA focuses on:
✔ Safety
✔ Hazard prevention
✔ Bloodborne pathogens
✔ Workplace exposure
❤ Bloodborne Pathogens
These are organisms that can spread through:
• Blood
• Certain body fluids
Examples:
• Hepatitis B
• Hepatitis C
• HIV
❤ Standard Precautions
Standard precautions mean:
Treat ALL patients as if they may carry infectious organisms.
Why?
Because you cannot always tell who is infected.
❤ Personal Protective Equipment (PPE)
PPE protects healthcare workers.
Examples:
🧤 Gloves
😷 Masks
🥽 Eye protection
🩺 Gowns
❤ When To Wear Gloves
Wear gloves when:
✔ Contact with blood/body fluids is possible
✔ Performing procedures involving open skin
✔ Cleaning contaminated equipment
❤ Hand Hygiene
The #1 infection prevention method:
⭐ Hand washing/hand hygiene
Perform hand hygiene:
Before patient contact
After patient contact
After removing gloves
After touching equipment
❤ Needlestick Safety
If exposed:
1. Wash area immediately
2. Report exposure
3. Follow facility protocol
4. Seek medical evaluation
❤ Equipment Cleaning
ECG equipment must be:
✔ Cleaned between patients
✔ Disinfected according to manufacturer instructions
✔ Maintained properly
Do NOT:
❌ Use damaged equipment
❌ Ignore infection control policies
❤ Electrical Safety
The ECG machine uses electricity.
Safety rules:
✔ Inspect cords
✔ Report damaged equipment
✔ Keep equipment away from liquids
✔ Use properly grounded outlets
❤ Emergency Situations
An EKG technician must recognize when immediate help is needed.
Examples:
Patient:
• Becomes unconscious
• Has chest pain
• Has difficulty breathing
• Has seizure
• Shows signs of cardiac arrest
❤ If a Patient Collapses During ECG
Priority:
1. Stop procedure
2. Assess patient
3. Call for help
4. Begin emergency response according to training
5. Activate emergency system
🚨 Never:
❌ Leave the patient alone during an emergency
❌ Continue the ECG while ignoring symptoms
❤ Chest Pain During ECG
If patient says:
"My chest hurts."
Do:
✔ Stop and assess
✔ Notify appropriate staff immediately
✔ Follow emergency protocol
Do NOT:
❌ Tell patient "you’re fine"
❌ Diagnose
❤ Documentation
Documentation must be:
✔ Accurate
✔ Complete
✔ Timely
✔ Objective
Document:
• Date/time
• Patient information
• Procedure performed
• Patient response
• Abnormal situations
• Repeat ECGs if needed
❤ Never Document:
❌ Personal opinions
Example:
"Patient was annoying."
Correct:
"Patient refused procedure."
❤ Professional Behavior
A professional EKG technician:
✔ Shows respect
✔ Maintains confidentiality
✔ Communicates clearly
✔ Remains calm
✔ Treats all patients equally
❤ Cultural Sensitivity
Respect:
• Beliefs
• Preferences
• Privacy needs
• Communication differences
❤ Difficult Patients
Remain:
✔ Calm
✔ Respectful
✔ Professional
Do NOT:
❌ Argue
❌ Become defensive
❌ Take behavior personally
❤ Communication Techniques
Good communication:
• Introduce yourself
• Use simple explanations
• Listen actively
• Confirm understanding
❤ Patient Positioning Review
Standard ECG:
⭐ Supine position
Patient should:
✔ Relax
✔ Avoid talking
✔ Keep still
✔ Breathe normally
🚨 NHA EXAM TRAPS
❌ "Room number is an acceptable patient identifier."
FALSE.
Use two identifiers.
❌ "An EKG technician can diagnose arrhythmias."
FALSE.
They recognize and report findings.
❌ "HIPAA allows discussing patients in public areas if names aren't used."
FALSE.
Private information can still be identifiable.
❌ "Gloves replace hand hygiene."
FALSE.
Hand hygiene is still required.
❌ "If a patient refuses an ECG, force them to complete it."
FALSE.
Respect refusal and notify provider.
⭐ MUST MEMORIZE COLD
🔥 Use TWO patient identifiers
🔥 HIPAA protects patient information
🔥 OSHA protects workers
🔥 Standard precautions apply to ALL patients
🔥 Hand hygiene is the #1 infection prevention method
🔥 EKG technicians do NOT diagnose
🔥 Document facts, not opinions
🔥 Protect patient privacy
🔥 Stop procedure if patient becomes unstable
🧠 Self-Quiz (No Peeking!)
1. What are two acceptable patient identifiers?
2. What does HIPAA protect?
3. What does OSHA focus on?
4. What is the purpose of standard precautions?
5. When should gloves be worn?
6. Can an EKG technician diagnose a heart attack?
7. What should you do if a patient refuses an ECG?
8. What is the correct position for a resting ECG?
9. What should you do if a patient collapses?
10. Why is documentation important?
💡 Abby's Memory Hacks
❤ "HIPAA = Hide Information, Protect All"
HIPAA = keep patient information private.
❤ "OSHA = Our Safety Helps All"
OSHA protects healthcare workers.
❤ "Two to Know"
Two identifiers before you go.
❤ "Facts, Not Feelings"
Document what happened.
Not your opinion.
🎯 NHA High-Yield Facts
If you know these, you will grab easy points:
1. Two patient identifiers
2. HIPAA basics
3. Standard precautions
4. PPE use
5. Scope of practice
6. Emergency response
7. Documentation rules
PART 7 – ECG ARTIFACTS & TROUBLESHOOTING (Fixing Bad Tracings)
❤ Why This Section Matters
An artifact is an unwanted electrical signal that appears on an ECG tracing but does not come from the patient's heart.
Think:
The ECG is trying to listen to the heart...
…but something else is making noise.
❤ Common Causes of Artifact
Artifacts can come from:
✔ Patient movement
✔ Muscle activity
✔ Poor electrode contact
✔ Electrical interference
✔ Improper skin preparation
✔ Loose wires
✔ Equipment problems
🚨 Golden Rule of Troubleshooting
Before assuming a patient has an abnormal rhythm:
ALWAYS check:
1. Is the patient moving?
2. Are the electrodes attached correctly?
3. Are the wires connected?
4. Is the patient comfortable?
5. Is there electrical interference?
❤ The 3 Major ECG Artifacts
The NHA LOVES these:
1. Somatic Tremor Artifact
2. Wandering Baseline
3. 60-Cycle Interference (AC Interference)
Know:
Appearance
Cause
Solution
❤ 1. Somatic Tremor Artifact
Also called:
⭐ Muscle Tremor Artifact
What Does It Look Like?
The ECG tracing appears:
• Jagged
• Shaky
• Irregular
• Messy
It may look like:
Atrial fibrillation
or
Ventricular activity
Cause
Muscle movement.
Examples:
• Shivering
• Tremors
• Parkinson's disease
• Patient anxiety
• Talking
• Tensing muscles
• Moving limbs
How To Fix It
✔ Ask patient to relax
✔ Keep patient warm
✔ Support arms and legs
✔ Ask patient not to talk
✔ Reduce muscle tension
🧠 Memory Trick
Somatic = Skeletal muscles
If muscles are moving...
Somatic artifact happens.
❤ 2. Wandering Baseline
What Does It Look Like?
The baseline slowly moves:
⬆ Up
⬇ Down
Like waves drifting across the page.
Cause
Usually caused by:
• Breathing
• Loose electrodes
• Poor skin contact
• Patient movement
How To Fix It
✔ Check electrode adhesion
✔ Clean skin
✔ Dry sweaty skin
✔ Ask patient to remain still
✔ Ensure cables are secure
🧠 Memory Trick
"Wandering = Walking"
The baseline is "walking" across the ECG paper.
❤ 3. 60-Cycle Interference
Also called:
⭐ AC Interference
(Alternating Current interference)
What Does It Look Like?
A very regular, fast, fuzzy pattern.
It may appear as:
• Uniform spikes
• Electrical noise
• Thickened baseline
Cause
Outside electrical sources.
Examples:
• Nearby electrical equipment
• Power cords
• Poor grounding
• Electrical devices
How To Fix It
✔ Make sure machine is grounded
✔ Move away from electrical sources
✔ Check cables
✔ Turn off unnecessary equipment
🧠 Memory Trick
60-cycle = electricity
Think:
"60 = outlets"
❤ Loose Electrode Artifact
Appearance:
Sudden:
• Flat line
• Irregular signal
• Missing waveform
Causes:
• Electrode falling off
• Poor adhesive
• Dirty skin
• Dry electrodes
Fix:
✔ Replace electrode
✔ Clean skin
✔ Reapply correctly
❤ Broken Lead Wire Artifact
Appearance:
A lead suddenly stops working.
May show:
• Flat line
• Intermittent signal
Fix:
✔ Check cable connections
✔ Replace damaged wires
✔ Verify equipment function
❤ Patient Movement Artifact
Causes:
• Talking
• Coughing
• Changing position
• Shifting in bed
Fix:
Explain:
"Please stay still and relaxed for a few seconds."
❤ Baseline vs Waveform
Important:
The baseline is the flat reference line.
The waves:
• P
• QRS
• T
move above and below the baseline.
❤ Troubleshooting Poor ECG Quality
Follow this order:
Step 1: Check the Patient
Ask:
"Are you comfortable?"
Look for:
• Tremors
• Talking
• Movement
• Shivering
Step 2: Check Electrodes
Look for:
• Loose stickers
• Poor contact
• Wrong placement
Step 3: Check Skin
Make sure:
✔ Clean
✔ Dry
✔ No lotion/oil
✔ Enough contact
Step 4: Check Equipment
Look for:
• Loose cables
• Damaged wires
• Electrical interference
❤ Common Artifact Comparison
Artifact Appearance Cause Fix
Somatic Tremor Jagged/shaky Muscle movement Relax patient
Wandering Baseline Drifting line Breathing/movement Improve contact
60-Cycle Interference Regular electrical noise Power interference Ground equipment
Loose Electrode Missing signal Poor contact Replace electrode
❤ Patient Factors That Create Artifact
Remember:
The patient is part of the ECG.
Artifact increases with:
• Anxiety
• Cold temperature
• Pain
• Tremors
• Shivering
• Talking
• Movement
❤ How To Prevent Artifact BEFORE It Happens
A good technician prevents problems.
Before starting:
✔ Explain procedure
✔ Make patient comfortable
✔ Warm cold patients
✔ Position correctly
✔ Prepare skin
✔ Apply electrodes firmly
✔ Ask patient to relax
❤ Artifact vs Arrhythmia
This is a VERY important concept.
Sometimes artifact can look like a dangerous rhythm.
Example:
A shaky tracing may look like ventricular fibrillation.
Before reacting:
CHECK THE PATIENT.
If the patient is:
✔ Awake
✔ Talking
✔ Has a pulse
✔ Looks comfortable
The tracing may be artifact.
🚨 NHA EXAM TRAPS
❌ "A jagged irregular baseline always means atrial fibrillation."
FALSE.
It may be muscle tremor artifact.
❌ "The best way to fix artifact is to immediately repeat the ECG."
FALSE.
First identify and correct the cause.
❌ "Artifact comes from abnormal heart electricity."
FALSE.
Artifact comes from outside interference.
❌ "A patient should hold their breath during every ECG."
FALSE.
Patients should breathe normally unless instructed otherwise.
⭐ MUST MEMORIZE COLD
🔥 Artifact = electrical interference NOT caused by the heart
🔥 Somatic tremor = muscle movement
🔥 Wandering baseline = movement/breathing/poor contact
🔥 60-cycle interference = electrical interference
🔥 Loose electrodes = poor contact
🔥 Always check the patient before assuming a dangerous rhythm
🔥 Good skin prep reduces artifact
🧠 Self-Quiz (No Peeking!)
1. What is an ECG artifact?
2. What causes somatic tremor artifact?
3. What does wandering baseline look like?
4. What causes 60-cycle interference?
5. How do you correct muscle tremor artifact?
6. What is the first thing you should check when an ECG looks abnormal?
7. Why is skin preparation important?
8. What artifact can mimic dangerous rhythms?
9. What should you do if an electrode comes loose?
10. What is the difference between artifact and arrhythmia?
💡 Abby's Memory Hacks
❤ "SMT = Shaky Muscle Tremor"
Somatic = Skeletal muscle
Movement = Messy tracing
❤ "Wandering = Walking Baseline"
The line literally wanders.
❤ "60 = Electricity"
60-cycle interference comes from electrical sources.
🎯 NHA High-Yield Facts
Know these and you will score:
1. Artifact is NOT the heart
2. Identify the type of artifact
3. Fix the cause before repeating
4. Check patient first
5. Proper electrode placement matters
PART 8A – RHYTHM INTERPRETATION FOUNDATIONS + NORMAL SINUS RHYTHM
❤ The 5-Step Rhythm Analysis Method
Every time you look at an ECG strip, use the same checklist.
This prevents guessing.
STEP 1: Determine the Rate
Ask:
“How fast is the heart beating?”
Normal adult resting heart rate:
⭐ 60–100 beats per minute
Methods to calculate rate:
300 Method
Used for regular rhythms.
Find the number of large boxes between R waves.
Formula:
300 ÷ number of large boxes = heart rate
Example:
4 large boxes between R waves:
300 ÷ 4 = 75 bpm
1500 Method
More precise.
Count small boxes between R waves.
Formula:
1500 ÷ small boxes = heart rate
Example:
20 small boxes:
1500 ÷ 20 = 75 bpm
6-Second Method
Used for irregular rhythms.
Count QRS complexes in 6 seconds.
Multiply by:
⭐ 10
Example:
7 QRS complexes:
7 × 10 = 70 bpm
STEP 2: Determine Rhythm Regularity
Ask:
Are the R-R intervals evenly spaced?
Regular Rhythm
The distance between each heartbeat is the same.
Example:
❤ ❤ ❤ ❤
Irregular Rhythm
The spacing changes.
Example:
❤ ❤ ❤ ❤ ❤
STEP 3: Look at P Waves
Ask:
Are P waves present?
Normal:
✔ One P wave before every QRS
✔ Same shape
✔ Upright in most leads
STEP 4: Measure PR Interval
Normal:
⭐ 0.12–0.20 seconds
(3–5 small boxes)
STEP 5: Measure QRS Duration
Normal:
⭐ Less than 0.12 seconds
❤ The Rhythm Checklist
Remember:
R – Rate
R – Rhythm
P – P waves
P – PR interval
Q – QRS
(“RRPPQ”)
❤ NORMAL SINUS RHYTHM (NSR)
This is the rhythm of a healthy heart.
What Does "Sinus" Mean?
Sinus means:
The impulse started in the:
⭐ SA Node
The heart's natural pacemaker.
Normal Sinus Rhythm Characteristics
1. Rate
❤ 60–100 bpm
2. Rhythm
Regular
The R-R intervals are evenly spaced.
3. P Waves
Present.
Every P wave looks the same.
There is:
⭐ One P wave before every QRS
4. PR Interval
Normal:
⭐ 0.12–0.20 seconds
5. QRS
Normal:
⭐ Less than 0.12 seconds
❤ Normal Sinus Rhythm Summary
Feature Finding
Rate 60–100 bpm
Rhythm Regular
P Waves Present, one before each QRS
PR Interval 0.12–0.20 sec
QRS <0.12 sec
Origin SA Node
🧠 Memory Trick
"Sinus = Same"
Normal sinus rhythm:
✔ Same rate
✔ Same P waves
✔ Same spacing
✔ Same pathway
❤ Why Normal Sinus Rhythm Matters
Every abnormal rhythm is compared to normal sinus rhythm.
If you know normal...
You can recognize abnormal.
❤ Sinus Bradycardia
Now we change ONE thing:
The heart rate becomes too slow.
Definition
Sinus bradycardia:
⭐ Normal sinus rhythm with a heart rate below 60 bpm.
Characteristics
Rate
⬇ Less than 60 bpm
Rhythm
Regular
P Waves
Present.
Normal.
One before each QRS.
PR Interval
Normal.
0.12–0.20 sec
QRS
Normal.
Less than 0.12 sec
The Difference:
Normal Sinus Rhythm:
60–100 bpm
↓
Sinus Bradycardia:
Below 60 bpm
Everything else may look normal.
❤ Causes of Sinus Bradycardia
Normal causes:
✔ Sleep
✔ Athletes
✔ Relaxation
Medical causes:
• Hypothyroidism
• Medication effects
• Increased vagal stimulation
• Heart disease
• SA node problems
❤ Symptoms
Some patients have no symptoms.
Possible symptoms:
• Dizziness
• Fatigue
• Weakness
• Fainting
• Shortness of breath
❤ Treatment Basics (NHA Level)
Treatment depends on symptoms.
A patient who is:
✔ Awake
✔ Stable
may only require monitoring.
A patient who is:
❌ Unstable
may require medical intervention.
🚨 NHA Exam Tip
Do NOT assume every slow rhythm is dangerous.
A healthy athlete may have sinus bradycardia.
❤ Sinus Tachycardia
Now the opposite.
The heart is beating too fast.
Definition
Sinus tachycardia:
⭐ Normal sinus rhythm with a heart rate above 100 bpm.
Characteristics
Rate
⬆ Greater than 100 bpm
Rhythm
Regular
P Waves
Present.
Normal.
One before each QRS.
PR Interval
Normal.
QRS
Normal.
❤ Causes of Sinus Tachycardia
Common causes:
✔ Exercise
✔ Stress
✔ Anxiety
✔ Fever
✔ Pain
✔ Dehydration
✔ Caffeine
✔ Medications
Medical causes:
• Blood loss
• Infection
• Hyperthyroidism
• Heart problems
❤ Symptoms
Possible:
• Palpitations
• Chest discomfort
• Shortness of breath
• Dizziness
❤ Treatment Basics
Treat the cause.
Example:
Fever → reduce fever
Dehydration → fluids
Pain → treat pain
🚨 NHA Exam Tip
Sinus tachycardia is not automatically a heart attack.
A normal response to exercise or stress can cause it.
❤ Sinus Arrhythmia
This rhythm is a little different.
Definition
Sinus arrhythmia:
⭐ Normal sinus rhythm where the rate varies with breathing.
Characteristics
Rate
Usually:
60–100 bpm
Rhythm
❌ Irregular
BUT...
The irregularity follows breathing.
P Waves
Present.
Normal.
PR Interval
Normal.
QRS
Normal.
❤ Why Does It Happen?
During breathing:
Inspiration:
Heart rate increases
Expiration:
Heart rate decreases
❤ Is It Dangerous?
Usually:
⭐ No.
It is common in:
• Young people
• Healthy individuals
🧠 Memory Trick
"Sinus Arrhythmia = Breathing Rhythm"
The heart speeds up and slows down with respiration.
❤ Comparison Table
Rhythm Rate Rhythm P Waves PR QRS
Normal Sinus 60–100 Regular Normal Normal Normal
Sinus Brady <60 Regular Normal Normal Normal
Sinus Tachy >100 Regular Normal Normal Normal
Sinus Arrhythmia Usually normal Irregular with breathing Normal Normal Normal
🚨 NHA EXAM TRAPS
❌ "Sinus bradycardia means the SA node stopped working."
FALSE.
The SA node is still working—just slower.
❌ "Sinus tachycardia always means heart disease."
FALSE.
Exercise and stress can cause it.
❌ "Sinus arrhythmia is always dangerous."
FALSE.
Often normal, especially in younger people.
⭐ MUST MEMORIZE COLD
🔥 Rhythm analysis: Rate → Rhythm → P waves → PR → QRS
🔥 Normal Sinus Rhythm: 60–100 bpm
🔥 Sinus Bradycardia: <60 bpm
🔥 Sinus Tachycardia:
100 bpm
🔥 Sinus Arrhythmia: Irregular with breathing
🔥 SA Node controls sinus rhythms
🔥 P wave before every QRS = sinus rhythm
🧠 Self-Quiz
1. What structure creates a sinus rhythm?
2. What is the normal adult heart rate?
3. What rate defines sinus bradycardia?
4. What rate defines sinus tachycardia?
5. What makes sinus arrhythmia different from other rhythms?
6. What are the five steps of rhythm interpretation?
7. What does one P wave before each QRS tell you?
8. What is a normal PR interval?
9. What is a normal QRS duration?
10. What method is used to calculate irregular rhythms?
💡 Abby's Memory Hacks
❤ "Normal = 60 to 100 and everything looks normal."
❤ "Brady = Below"
• Brady = Below 60
❤ "Tachy = Too quick"
• Tachy = Too fast (>100)
❤ "Sinus = SA Node"
If the SA node starts it...
It is a sinus rhythm.
🎯 NHA High-Yield Facts
Know these instantly:
• Normal sinus rhythm
• Sinus bradycardia
• Sinus tachycardia
• Sinus arrhythmia
• Rate ranges
• P wave appearance
• PR interval
• QRS width
• Rhythm interpretation steps
PART 8B – ATRIAL ARRHYTHMIAS
❤ What Are Atrial Arrhythmias?
Atrial arrhythmias are abnormal rhythms that begin in the:
⭐ Atria (upper chambers of the heart)
Normally:
SA Node
↓
Atria
↓
AV Node
↓
Ventricles
But with atrial arrhythmias:
The atria are firing abnormally.
❤ Why Do Atrial Rhythms Matter?
Because the atria help fill the ventricles with blood.
When the atria are not contracting properly:
⬇ Less blood reaches ventricles
⬇ Cardiac output may decrease
❤ PART 1 — Premature Atrial Contractions (PACs)
Definition
A PAC is:
⭐ An early heartbeat that begins in the atria instead of the SA node.
Think:
The atria "jump ahead" and fire too soon.
🧠 Memory Trick
PAC:
Premature
Atrial
Contraction
=
"Premature Atria Cut in line"
😂
❤ What Causes PACs?
Common causes:
✔ Stress
✔ Caffeine
✔ Alcohol
✔ Lack of sleep
✔ Nicotine
✔ Anxiety
✔ Stimulant medications
Medical causes:
• Heart disease
• Electrolyte abnormalities
• Lung disease
❤ PAC ECG Characteristics
Rate
Usually normal overall.
Rhythm
Usually:
❌ Irregular because of the early beat.
P Wave
This is the key!
A PAC has:
⭐ An early abnormal-looking P wave
Why?
Because the impulse did NOT come from the SA node.
PR Interval
Usually normal but may vary.
QRS
Usually:
⭐ Normal and narrow
because the ventricles are activated through the normal pathway.
❤ How PACs Look
Normal beat:
P → QRS → T
Then suddenly:
Early weird P → QRS → T
Then back to normal.
❤ Are PACs Dangerous?
Usually:
⭐ No.
Many healthy people have occasional PACs.
❤ NHA PAC Clue
If you see:
✔ Early beat
✔ Different P wave
✔ Normal QRS
Think:
⭐ PAC
❤ PART 2 — Atrial Flutter
Definition
Atrial flutter occurs when the atria:
⭐ Beat very rapidly in a regular pattern.
The atria are not beating normally.
Instead:
They are "fluttering."
Cause
A rapid electrical circuit develops in the atria.
This creates a repeating pattern.
❤ ECG Characteristics
Rate
Atrial rate:
⭐ Around 250–350 bpm
Ventricular rate varies depending on conduction.
Rhythm
Usually:
Regular
(especially with consistent conduction)
P Waves
This is the BIG clue.
Normal P waves disappear.
Instead:
You see:
⭐ Flutter waves
Also called:
"F waves"
❤ Appearance
Flutter waves often look like:
🦷 Saw teeth
or
A picket fence
❤ PR Interval
Usually difficult to measure because normal P waves are absent.
❤ QRS
Usually:
Narrow
unless another conduction problem exists.
❤ Common Causes of Atrial Flutter
• Heart disease
• High blood pressure
• Lung disease
• Previous heart surgery
❤ Symptoms
Possible:
• Palpitations
• Fatigue
• Shortness of breath
• Dizziness
• Chest discomfort
🧠 Memory Trick
Flutter:
"Flutter = Fence"
Because the waves look like a saw-tooth fence.
❤ PART 3 — Atrial Fibrillation (AFib)
Definition
Atrial fibrillation is:
⭐ Chaotic electrical activity in the atria causing ineffective atrial contraction.
The atria are basically:
"Electrically confused."
Why Is AFib Important?
Because blood may pool in the atria.
Pooling blood increases risk of:
⭐ Blood clots
Which increases risk of:
⭐ Stroke
❤ ECG Characteristics
Rate
Atrial rate:
Very fast
(usually 300–600 bpm)
Rhythm
⭐ Irregularly irregular
THIS IS THE KEY PHRASE.
Meaning:
No pattern.
No consistent spacing.
P Waves
Absent.
Instead:
You see:
⭐ Fibrillatory waves
Small, chaotic baseline waves.
PR Interval
Not measurable.
No consistent P waves.
QRS
Usually:
Narrow
❤ How To Recognize AFib
Look for:
1. No P waves
2. Irregularly irregular rhythm
3. Wavy baseline
Think:
⭐ AFib
❤ Causes of AFib
Common causes:
• Hypertension
• Coronary artery disease
• Heart valve disease
• Aging
• Hyperthyroidism
❤ Symptoms
Some patients:
Have no symptoms.
Others:
• Palpitations
• Fatigue
• Shortness of breath
• Dizziness
• Chest discomfort
🧠 Memory Trick
AFib:
"A Fib = A Freaking Irregular Beat"
😂
Remember:
Irregularly irregular.
❤ PART 4 — Supraventricular Tachycardia (SVT)
Definition
SVT means:
⭐ A very fast rhythm that begins above the ventricles.
"Supra" = above
"Ventricular" = ventricles
Where Does It Start?
Usually:
Atria or AV junction.
❤ ECG Characteristics
Rate
Usually:
⭐ 150–250 bpm
Rhythm
Usually:
Regular
P Waves
May be:
• Hidden
• Difficult to see
• Buried inside QRS
PR Interval
Often:
Not measurable
QRS
Usually:
Narrow
❤ Symptoms
Because the heart is beating so fast:
• Palpitations
• Dizziness
• Shortness of breath
• Chest discomfort
• Anxiety
❤ Causes
Possible triggers:
• Stress
• Caffeine
• Alcohol
• Heart disease
🧠 Memory Trick
SVT:
"Super Very Tachy"
Super fast heartbeat.
❤ Atrial Rhythm Comparison Chart
Rhythm Rate Rhythm P Waves QRS
PAC Usually normal Irregular beat Early abnormal P Narrow
Atrial Flutter Atrial 250–350 Often regular Saw-tooth flutter waves Narrow
AFib Very fast atria Irregularly irregular No P waves Usually narrow
SVT 150–250 Regular Hidden/absent Narrow
🚨 NHA EXAM TRAPS
❌ "AFib has regular R-R intervals."
FALSE.
AFib is:
⭐ Irregularly irregular.
❌ "Atrial flutter has normal P waves."
FALSE.
Flutter has:
⭐ Saw-tooth flutter waves.
❌ "PACs always require emergency treatment."
FALSE.
Occasional PACs are common.
❌ "SVT usually has wide QRS complexes."
FALSE.
SVT usually has:
⭐ Narrow QRS.
⭐ MUST MEMORIZE COLD
🔥 PAC = early abnormal P wave
🔥 Atrial Flutter = saw-tooth flutter waves
🔥 AFib = no P waves + irregularly irregular rhythm
🔥 SVT = very fast regular narrow rhythm
🔥 Atrial rhythms start above ventricles
🔥 Narrow QRS usually means normal ventricular conduction
🧠 Self-Quiz
1. Where do atrial arrhythmias originate?
2. What makes a PAC different from a normal beat?
3. What does atrial flutter look like?
4. What is the key rhythm description for AFib?
5. Why is AFib associated with stroke risk?
6. What happens to P waves in AFib?
7. What is the typical heart rate range for SVT?
8. Are PACs usually dangerous?
9. Which rhythm has saw-tooth waves?
10. Which rhythm has an irregularly irregular rhythm?
💡 Abby's Memory Hacks
❤ PAC = "Popped Ahead Contraction"
• The P wave comes early.
❤ Flutter = Fence
• Saw-tooth fence pattern.
❤ AFib = Absolute Forgetting of P waves
• No P waves.
• Completely irregular.
❤ SVT = Super Very Tachy
• Super fast, usually narrow.
🎯 NHA High-Yield Facts
If you remember only these:
⭐ PAC → early abnormal P wave
⭐ Flutter → saw-tooth waves
⭐ AFib → no P waves + irregularly irregular
⭐ SVT → fast regular narrow rhythm
PART 8C – JUNCTIONAL & VENTRICULAR RHYTHMS
❤ Before We Start: The Location Matters
Remember the conduction system:
SA Node ⬇ Atria ⬇ AV Node ⬇ Bundle of His ⬇ Bundle Branches ⬇ Purkinje Fibers ⬇ Ventricles
❤ Junctional Rhythms
What Does "Junctional" Mean?
Junctional rhythms begin in the:
⭐ AV junction
The AV junction includes:
• AV node
• Surrounding tissue
❤ Why Does a Junctional Rhythm Happen?
Usually because:
The SA node is not firing correctly.
The AV junction becomes the backup pacemaker.
❤ Junctional Pacemaker Rate
Remember:
SA Node:
60–100 bpm
AV Junction:
⭐ 40–60 bpm
Purkinje:
20–40 bpm
🧠 Memory Trick
The farther down the conduction system:
⬇
The slower the rate.
❤ Junctional Rhythm Characteristics
Rate
Usually:
40–60 bpm
Rhythm
Regular
P Waves
This is the key!
P waves may be:
• Missing
• Hidden
• Inverted
Why?
Because the impulse is not traveling normally through the atria.
PR Interval
May be:
• Short
• Normal
• Not measurable
QRS
Usually:
⭐ Narrow
Because the ventricles are activated normally.
❤ Junctional Rhythm Summary
Feature Finding
Origin AV junction
Rate 40–60 bpm
Rhythm Regular
P Waves Absent, inverted, or hidden
QRS Narrow
❤ Causes of Junctional Rhythms
Possible causes:
• SA node failure
• Medication effects
• Increased vagal tone
• Heart disease
• Digoxin toxicity
❤ Symptoms
Depends on rate.
Possible:
• Fatigue
• Dizziness
• Low blood pressure
❤ Premature Ventricular Contractions (PVCs)
NOW THIS ONE IS IMPORTANT.
Definition
A PVC is:
⭐ An early heartbeat that begins in the ventricles.
The ventricle "fires early."
🧠 Memory Trick
PVC:
Premature
Ventricular
Contraction
=
"Ventricles jumped the line."
❤ PVC Characteristics
Rate
Depends on underlying rhythm.
Rhythm
Usually:
Irregular
because an early beat interrupts the rhythm.
P Wave
Usually:
❌ No P wave before the PVC
Why?
The impulse started in the ventricle, not the atria.
QRS
The BIG clue:
⭐ Wide and bizarre QRS
Usually:
Greater than 0.12 seconds
❤ What Does a PVC Look Like?
Normal:
P → QRS → T
Then:
BIG wide beat
Then:
Back to normal.
❤ PVC Causes
Common:
✔ Stress
✔ Caffeine
✔ Alcohol
✔ Lack of sleep
✔ Electrolyte imbalance
✔ Heart disease
❤ Are PVCs Dangerous?
Depends.
Occasional PVCs:
Often harmless.
Frequent PVCs:
May require evaluation.
❤ PVC Patterns
You may see:
Bigeminy
Every other beat is a PVC.
Example:
Normal
PVC
Normal
PVC
Trigeminy
Every third beat is a PVC.
Example:
Normal
Normal
PVC
Couplets
Two PVCs in a row.
Runs
Three or more PVCs in a row.
❤ NHA Tip
The more PVCs:
The more concern.
❤ Ventricular Tachycardia (V-Tach)
This is a serious rhythm.
Definition
Ventricular tachycardia is:
⭐ A rapid rhythm originating in the ventricles.
❤ ECG Characteristics
Rate
Usually:
⭐ 100–250 bpm
Rhythm
Usually:
Regular
P Waves
Usually:
Absent or not visible
QRS
⭐ Wide and abnormal
❤ Why Is V-Tach Dangerous?
The ventricles are beating so fast they may not pump blood effectively.
This can decrease:
⬇ Cardiac output
⬇ Oxygen delivery
❤ Symptoms
Patient may have:
• Dizziness
• Chest pain
• Low blood pressure
• Loss of consciousness
❤ Treatment Basics
Depends on patient condition.
May include:
• Emergency medical response
• Cardioversion
• Defibrillation if pulseless
❤ Stable vs Unstable
Stable:
Patient has pulse and acceptable condition.
Unstable:
• No pulse
• Severe symptoms
• Poor circulation
❤ Ventricular Fibrillation (V-Fib)
This is a cardiac emergency.
Definition
Ventricular fibrillation is:
⭐ Chaotic electrical activity in the ventricles.
The ventricles are:
"Quivering"
instead of squeezing.
❤ ECG Appearance
Looks like:
• Chaotic
• Irregular
• No identifiable P waves
• No identifiable QRS complexes
❤ What Is Happening?
The ventricles are not pumping blood.
No effective contraction.
❤ Patient Condition
Patient is:
❌ Unresponsive
❌ Pulseless
❌ Not breathing normally
❤ Treatment
Emergency:
⭐ CPR
⭐ Defibrillation
🧠 Memory Trick
V-Fib:
"V = Very chaotic"
❤ Asystole
The flatline rhythm.
Definition
Asystole:
⭐ Absence of detectable cardiac electrical activity.
ECG Appearance
A flat line.
No:
• P waves
• QRS complexes
• T waves
Patient Condition
Usually:
Unresponsive
No pulse
Treatment
CPR
Emergency response
🚨 Important:
Asystole is NOT treated with defibrillation.
Why?
Because there is no electrical activity to reset.
❤ Ventricular Rhythm Comparison
Rhythm Rate P Waves QRS Key Feature
Junctional 40–60 Missing/inverted Narrow AV junction origin
PVC Variable No P before beat Wide Early ventricular beat
V-Tach 100–250 Usually absent Wide Fast ventricular rhythm
V-Fib Chaotic None None Quivering ventricles
Asystole None None None Flatline
🚨 NHA EXAM TRAPS
❌ "PVCs have narrow QRS complexes."
FALSE.
PVCs have:
⭐ Wide, bizarre QRS.
❌ "V-Fib has organized QRS complexes."
FALSE.
V-Fib has chaotic electrical activity.
❌ "Asystole should be shocked immediately."
FALSE.
CPR and emergency response are priorities.
❌ "Junctional rhythms always have visible normal P waves."
FALSE.
P waves may be absent, inverted, or hidden.
⭐ MUST MEMORIZE COLD
🔥 Junctional rhythm: 40–60 bpm
🔥 PVC: Early beat + wide bizarre QRS + no P wave
🔥 V-Tach: Fast + wide QRS + emergency
🔥 V-Fib: Chaotic + no pulse
🔥 Asystole: Flatline + no electrical activity
🔥 Ventricular rhythms = usually wide QRS
🧠 Self-Quiz
1. Where do junctional rhythms originate?
2. What is the rate of the AV junction?
3. What makes a PVC different from a PAC?
4. What does a PVC look like on ECG?
5. What makes V-Tach dangerous?
6. What does V-Fib look like?
7. Is asystole shocked?
8. What is the QRS width in ventricular rhythms?
9. What does "wide and bizarre" usually suggest?
10. What is the difference between V-Fib and asystole?
💡 Abby's Memory Hacks
❤ "PVC = Please View the Chunky QRS"
• Wide and ugly-looking.
❤ "V-Tach = Ventricles Very Fast"
❤ "V-Fib = Ventricles Flopping"
❤ "Flatline = No electricity"
🎯 NHA High-Yield Facts
Know these instantly:
⭐ PVC = wide premature beat
⭐ V-Tach = dangerous fast wide rhythm
⭐ V-Fib = no effective heartbeat
⭐ Asystole = no electrical activity
⭐ Junctional = AV node backup rhythm
PART 8D – HEART BLOCKS & CONDUCTION DELAYS
❤ What Is a Heart Block?
A heart block occurs when:
⭐ The electrical signal from the atria does not properly travel to the ventricles.
The problem usually occurs at:
• AV node
• Bundle of His
• Bundle branches
❤ Normal Electrical Pathway Review
SA Node
⬇
Atria contract
⬇
AV Node
⬇
Bundle of His
⬇
Bundle Branches
⬇
Purkinje Fibers
⬇
Ventricles contract
❤ Heart Block Categories
There are three main AV blocks:
1⃣ First-degree AV block
2⃣ Second-degree AV block
• Type I (Mobitz I / Wenckebach)
• Type II (Mobitz II)
3⃣ Third-degree AV block (Complete Heart Block)
❤ PART 1 — First-Degree AV Block
Definition
First-degree AV block means:
⭐ The electrical signal is delayed at the AV node.
BUT…
Every signal still gets through.
Think:
🚦 Traffic slowdown
Not a complete stop.
ECG Characteristics
Rate
Usually normal.
Rhythm
Regular.
P Waves
Present.
Normal.
PR Interval
THIS IS THE KEY.
⭐ PR interval is prolonged.
Greater than:
0.20 seconds
(>5 small boxes)
QRS
Usually normal.
❤ The Secret to First Degree
Everything looks normal except:
⏱
The PR interval is too long.
Memory Trick:
"First degree = First thing is PR gets longer."
Causes
• Aging
• Heart disease
• Medications
• Increased vagal tone
Is It Dangerous?
Usually:
⭐ Not immediately dangerous.
Often monitored.
❤ PART 2 — Second-Degree AV Block Type I
Mobitz I / Wenckebach
Definition
Some electrical impulses fail to reach the ventricles.
The pattern:
The PR interval gets longer…
longer…
longer…
then:
💥 DROP!
A QRS disappears.
ECG Characteristics
Rate
Usually slower.
Rhythm
Irregular.
Because beats are dropped.
P Waves
Present.
But:
Some P waves are not followed by QRS.
PR Interval
⭐ Progressively lengthens.
Then a QRS is dropped.
QRS
Usually normal.
Classic Pattern:
PR
PR
LONGER PR
DROP
Repeat
Memory Trick:
"Wenckebach = We keep waiting"
The PR interval keeps waiting longer and longer before a beat drops.
Causes
• Increased vagal tone
• Inferior heart attack
• Medication effects
Is It Dangerous?
Often less serious than Mobitz II.
❤ PART 3 — Second-Degree AV Block Type II
Mobitz II
Definition
Some electrical signals suddenly fail to reach the ventricles.
Unlike Type I:
The PR interval does NOT gradually increase.
ECG Characteristics
Rate
Variable.
Rhythm
Usually irregular.
P Waves
Present.
BUT:
Some P waves have no QRS after them.
PR Interval
⭐ Constant
The PR stays the same...
Then suddenly:
DROP!
QRS
May be wide.
The Difference:
Mobitz I:
PR gets longer → Drop
Mobitz II:
Normal PR → Drop
Memory Trick:
"Type II = Two things stay the same"
1. PR stays the same
2. Then QRS suddenly disappears
Why Is Mobitz II Dangerous?
Because it can progress to:
⭐ Complete heart block
Causes:
• Heart damage
• Bundle branch disease
• Myocardial infarction
❤ PART 4 — Third-Degree AV Block
Complete Heart Block
Definition
The atria and ventricles are completely disconnected.
The atria:
"Do their own thing."
The ventricles:
"Do their own thing."
ECG Characteristics
Rate
Atrial rate:
Faster
Ventricular rate:
Slower
Rhythm
Regular
BUT:
Atrial and ventricular rhythms are independent.
P Waves
Present.
PR Interval
❌ No consistent PR interval.
Because:
P waves and QRS complexes are unrelated.
QRS
May be wide or narrow depending on escape rhythm.
Key Phrase:
⭐ AV dissociation
The atria and ventricles are no longer communicating.
Symptoms
May include:
• Dizziness
• Fainting
• Low blood pressure
• Fatigue
Treatment
Often requires:
⭐ Pacemaker
Memory Trick:
"Third degree = They broke up."
The atria and ventricles are no longer talking.
😂
❤ Heart Block Comparison Chart
Block PR Interval Dropped Beats? Key Feature
First Degree Long but constant No Delayed conduction
Mobitz I Gets longer Yes Progressive lengthening
Mobitz II Constant Yes Sudden drops
Third Degree No pattern Yes Atria & ventricles separate
❤ Bundle Branch Blocks (BBB)
Definition
A bundle branch block occurs when:
⭐ Electrical conduction through one bundle branch is delayed or blocked.
The ventricles still activate…
but one side is slower.
Two Types:
1. Right Bundle Branch Block (RBBB)
2. Left Bundle Branch Block (LBBB)
ECG Characteristics
Usually:
⭐ Wide QRS
Greater than:
0.12 seconds
Why?
Because ventricular activation takes longer.
Causes
• Heart disease
• Previous heart attack
• Structural heart problems
NHA Tip:
The most important thing to recognize:
Bundle branch block =
⭐ Wide QRS
❤ Pacemaker Rhythms
Why Are Pacemakers Used?
Pacemakers help control heart rhythm when:
• SA node fails
• Heart block occurs
• Heart rate is too slow
How Does a Pacemaker Work?
It sends:
⭐ Electrical impulses
to stimulate the heart.
ECG Appearance
Pacemaker spikes may appear before:
• P waves OR
• QRS complexes
depending on placement.
Pacemaker Types
Atrial Pacemaker
Stimulates atria.
Spike before P wave.
Ventricular Pacemaker
Stimulates ventricles.
Spike before QRS.
Dual Chamber Pacemaker
Stimulates both.
❤ Pacemaker Troubleshooting
Possible problems:
Failure to Fire
No spike when one is needed.
Failure to Capture
Spike appears…
but no heartbeat follows.
Failure to Sense
Pacemaker does not recognize the heart's activity.
🚨 NHA EXAM TRAPS
❌ "First-degree AV block means beats are missing."
FALSE.
All beats still conduct.
❌ "Mobitz I has constant PR intervals."
FALSE.
PR gradually increases.
❌ "Mobitz II is less serious than Mobitz I."
FALSE.
Mobitz II is more dangerous.
❌ "Third-degree block means the heart stops."
FALSE.
The atria and ventricles are just disconnected.
❌ "Wide QRS always means ventricular rhythm."
FALSE.
Bundle branch blocks can also widen QRS.
⭐ MUST MEMORIZE COLD
🔥 First-degree: Long PR, every beat conducts
🔥 Mobitz I: Longer, longer, drop
🔥 Mobitz II: Same PR, sudden drop
🔥 Third-degree: No relationship between P waves and QRS
🔥 Bundle branch block: Wide QRS
🔥 Pacemaker: Electrical spike before stimulated chamber
🧠 Self-Quiz
1. What causes a heart block?
2. What is the main abnormality in first-degree AV block?
3. What happens to PR intervals in Mobitz I?
4. What happens to PR intervals in Mobitz II?
5. Why is Mobitz II dangerous?
6. What does AV dissociation mean?
7. What is the hallmark of third-degree heart block?
8. What does a bundle branch block cause?
9. Where can pacemaker spikes appear?
10. What is failure to capture?
💡 Abby's Memory Hacks
❤ "First = PR First gets long"
❤ "Wenckebach = Walk longer then drop"
❤ "Mobitz II = Two stays true: PR stays the same"
❤ "Third degree = Three separate worlds"
❤ "BBB = Big Broad Beats" (Bundle Branch Block = Wide QRS)
🎯 NHA High-Yield Facts
If you know these:
⭐ PR >0.20 = First-degree block
⭐ Progressive PR lengthening = Mobitz I
⭐ Constant PR + dropped QRS = Mobitz II
⭐ No relationship between P and QRS = Complete heart block
⭐ Wide QRS = ventricular conduction problem
Remember:
⚠ EKG TECHS DO NOT DIAGNOSE MIs.
Your job:
✅ Recognize abnormal findings ✅ Obtain a clear tracing ✅ Notify appropriate personnel ✅ Follow emergency protocol
PART 9 – 12-LEAD ECG, ISCHEMIA, INJURY & MYOCARDIAL INFARCTION (MI)
❤ The Big Picture
The heart muscle needs:
🫀 Oxygen 🫀 Blood flow 🫀 Nutrients
The coronary arteries supply blood to the heart.
If blood flow decreases:
⬇ Oxygen supply
↓
Heart muscle becomes stressed
↓
Injury can occur
↓
Heart tissue may die
❤ Coronary Artery Blood Supply
The major coronary arteries:
1. Right Coronary Artery (RCA)
Supplies:
• Right ventricle
• Inferior portion of heart
• Often SA/AV nodes
2. Left Main Coronary Artery
Branches into:
Left Anterior Descending (LAD)
Supplies:
• Anterior wall
• Septum
Left Circumflex (LCX)
Supplies:
• Lateral wall
❤ What Is Ischemia?
Ischemia = Reduced blood flow and oxygen to heart tissue
The heart muscle is struggling.
BUT:
The tissue is not dead.
ECG Finding:
⭐ ST depression
and/or
⭐ T-wave changes
Memory Trick:
Ischemia = "Insufficient Oxygen"
The heart is hungry for oxygen.
❤ What Is Injury?
Heart muscle is actively being damaged.
This is more serious than ischemia.
ECG Finding:
⭐ ST elevation
Memory Trick:
Injury = ST goes UP
❤ What Is Infarction?
A myocardial infarction (MI) means:
⭐ Death of heart muscle tissue due to lack of blood supply.
Commonly called:
❤ Heart attack
ECG Findings:
Possible:
⭐ ST elevation
⭐ Pathologic Q waves
⭐ T-wave changes
❤ The 3 Stages of Coronary Problems
Think:
1. Ischemia
⬇ Oxygen
ECG:
ST depression
2. Injury
Active damage
ECG:
ST elevation
3. Infarction
Dead tissue
ECG:
Q waves
🧠 Memory Trick:
"DUP"
Depression = ischemia
Up = injury
Pathologic Q = permanent damage
❤ The 12-Lead ECG Views
A 12-lead ECG does NOT look at only one part of the heart.
Different leads view different areas.
❤ Lead Groups
The heart is divided into territories:
1. Inferior
2. Anterior
3. Septal
4. Lateral
❤ Inferior Leads
Leads:
⭐ II, III, aVF
Look at:
Bottom (inferior) portion of heart
Memory Trick:
"Bottom = Feet"
aVF:
"Foot"
❤ Anterior Leads
Leads:
⭐ V3, V4
Look at:
Front of left ventricle
❤ Septal Leads
Leads:
⭐ V1, V2
Look at:
Septum
❤ Lateral Leads
Leads:
⭐ I, aVL, V5, V6
Look at:
Side wall of heart
❤ Territory Table
Area Leads
Septal V1–V2
Anterior V3–V4
Lateral I, aVL, V5–V6
Inferior II, III, aVF
❤ ST Segment
The ST segment represents:
The time between ventricular depolarization and repolarization.
Basically:
The period after the QRS before the T wave.
❤ ST Elevation
ST elevation means:
The ST segment rises above baseline.
Possible Cause:
⭐ Acute myocardial injury
Especially:
STEMI
(ST Elevation Myocardial Infarction)
Technician Action:
If new ST elevation appears:
🚨 Notify provider immediately.
❤ ST Depression
ST depression means:
The ST segment drops below baseline.
Possible Causes:
• Ischemia
• Reduced oxygen supply
❤ T-Wave Changes
The T wave represents:
⭐ Ventricular repolarization
Abnormal T Waves
May include:
Tall peaked T waves
Possible:
Electrolyte abnormalities
Inverted T waves
Possible:
Ischemia
❤ Q Waves
Q waves can indicate:
⭐ Previous myocardial infarction
A pathologic Q wave suggests:
Heart muscle has been damaged.
❤ STEMI vs NSTEMI
STEMI
ST Elevation Myocardial Infarction
ECG:
⭐ ST elevation
Usually indicates:
Complete blockage of coronary artery.
NSTEMI
Non-ST Elevation Myocardial Infarction
ECG:
May show:
• ST depression
• T-wave changes
🚨 Important:
EKG technicians do NOT decide:
"This is STEMI."
They recognize:
"Abnormal ECG changes requiring immediate attention."
❤ Reciprocal Changes
This is an important concept.
Sometimes:
One area of the heart shows ST elevation…
while the opposite area shows:
ST depression.
This is called:
⭐ Reciprocal change
Memory Trick:
"Opposite wall reacts opposite."
❤ MI Lead Recognition
Example:
ECG shows ST elevation in:
II, III, aVF
Think:
Inferior wall involvement
ST elevation in:
V1-V2
Think:
Septal involvement
ST elevation in:
V3-V4
Think:
Anterior involvement
ST elevation in:
I, aVL, V5-V6
Think:
Lateral involvement
❤ Emergency Symptoms of MI
Possible symptoms:
• Chest pressure/pain
• Pain radiating to arm/jaw/back
• Shortness of breath
• Sweating
• Nausea
• Weakness
❤ Silent MI
Some patients may have:
Few or no symptoms.
More common in:
• Older adults
• People with diabetes
❤ EKG Technician Response to Possible MI
If patient reports symptoms:
1. Stay calm
2. Stop unnecessary activity
3. Notify healthcare provider/emergency team
4. Obtain ECG quickly if ordered
5. Follow facility protocol
🚨 Do NOT:
❌ Tell patient "you are having a heart attack"
❌ Leave patient alone
❌ Delay reporting abnormal findings
🚨 NHA EXAM TRAPS
❌ "ST elevation means ischemia."
FALSE.
ST elevation suggests:
⭐ Injury
❌ "ST depression means heart muscle is dead."
FALSE.
ST depression is associated with:
⭐ Ischemia
❌ "EKG technicians diagnose myocardial infarctions."
FALSE.
They recognize and report findings.
❌ "V1 and V2 view the inferior wall."
FALSE.
V1-V2 = septal
⭐ MUST MEMORIZE COLD
🔥 Ischemia = ST depression
🔥 Injury = ST elevation
🔥 Infarction = Q waves
🔥 Inferior = II, III, aVF
🔥 Septal = V1, V2
🔥 Anterior = V3, V4
🔥 Lateral = I, aVL, V5, V6
🔥 ST elevation = emergency finding
🔥 Techs recognize and report, not diagnose
🧠 Self-Quiz
1. What does ischemia mean?
2. What ECG change suggests injury?
3. What ECG change may suggest infarction?
4. Which leads show inferior heart?
5. Which leads show lateral heart?
6. Which leads show septal heart?
7. What does the T wave represent?
8. What does ST depression suggest?
9. What should an EKG technician do with new ST elevation?
10. Can an EKG technician diagnose an MI?
💡 Abby's Memory Hacks
❤ "ST Up = Injury Up"
ST elevation = injured heart muscle.
❤ "II III aVF = Down Below"
Inferior = bottom.
❤ "V1 V2 = Septal Crew"
❤ "V3 V4 = Front Door"
Anterior = front.
❤ "I aVL V5 V6 = Left Side View"
Lateral = side.
🎯 NHA High-Yield Facts
Know these and you are collecting points:
⭐ Lead territories ⭐ ST elevation vs depression ⭐ T-wave changes ⭐ Q waves ⭐ MI symptoms ⭐ Emergency response
PART 10 – STRESS TESTING, HOLTER MONITORS, TELEMETRY & AMBULATORY ECG MONITORING
❤ Overview: Types of ECG Monitoring
Different ECG tests are used depending on the patient's needs.
The main types:
1. Resting 12-lead ECG
2. Exercise stress test
3. Holter monitor
4. Event monitor
5. Telemetry monitoring
❤ 1. Resting 12-Lead ECG Review
A resting ECG records:
⭐ The heart’s electrical activity while the patient is not exercising.
Used For:
• Chest pain evaluation
• Arrhythmia detection
• Baseline cardiac assessment
• Pre-operative testing
• Routine screening
Patient Preparation:
The patient should:
✔ Be relaxed
✔ Lie supine
✔ Avoid talking
✔ Remain still
✔ Have proper electrode placement
❤ 2. Exercise Stress Testing
Definition
An exercise stress test measures:
⭐ How the heart responds to physical activity.
During exercise:
The heart needs more:
• Oxygen
• Blood flow
The test may reveal problems that are not obvious at rest.
❤ Why Is a Stress Test Done?
Used to evaluate:
✔ Chest pain
✔ Exercise tolerance
✔ Possible coronary artery disease
✔ Heart rhythm problems during activity
❤ How Stress Testing Works
The patient usually exercises on:
🏃 Treadmill
OR
🚲 Stationary bicycle
The workload increases gradually.
The healthcare team monitors:
• ECG
• Heart rate
• Blood pressure
• Symptoms
❤ EKG Technician Role During Stress Testing
The technician may:
✅ Prepare patient
✅ Apply electrodes
✅ Obtain baseline ECG
✅ Monitor ECG tracing
✅ Monitor patient response
✅ Report abnormal findings
The technician does NOT:
❌ Diagnose
❌ Interpret results independently
❌ Make medical decisions
❤ Before a Stress Test
The patient may be instructed to:
✔ Wear comfortable clothing
✔ Avoid heavy meals beforehand
✔ Avoid caffeine if instructed
✔ Take medications as directed by provider
❤ During a Stress Test
Monitor:
Heart Rate
Is the heart responding appropriately?
Blood Pressure
Watch for abnormal changes.
ECG Changes
Look for:
• ST changes
• Arrhythmias
Symptoms
Ask about:
• Chest pain
• Dizziness
• Shortness of breath
• Fatigue
🚨 Stop Test If Patient Has:
Possible warning signs:
🚨 Severe chest pain
🚨 Severe shortness of breath
🚨 Fainting
🚨 Dangerous rhythm changes
🚨 Severe blood pressure changes
❤ Recovery Period
After exercise:
The patient continues monitoring until:
✔ Heart rate decreases
✔ Symptoms improve
✔ ECG returns toward baseline
❤ 3. Holter Monitor
Definition
A Holter monitor is:
⭐ A portable ECG device that records heart activity continuously for an extended period.
Usually:
24–48 hours
(sometimes longer depending on device)
Why Use a Holter?
It detects problems that may not happen during a short ECG.
Examples:
• Intermittent arrhythmias
• Palpitations
• Unexplained dizziness
• Fainting episodes
❤ How It Works
Small electrodes are placed on the patient's chest.
The patient wears:
A small recording device.
The patient continues normal activities.
❤ Holter Monitor Patient Instructions
VERY TESTABLE.
Patients should:
✅ Keep the monitor dry
✅ Keep a diary of symptoms
✅ Record activities and times
✅ Avoid removing electrodes
❤ Symptom Diary
The patient records:
• Time symptoms occur
• Activity being performed
• Feelings/symptoms
Example:
"2:30 PM — felt heart racing while walking."
❤ EKG Technician Responsibilities
The technician may:
✔ Apply electrodes
✔ Explain instructions
✔ Check equipment
✔ Download data
✔ Document information
❤ 4. Event Monitor
Definition
An event monitor records ECG activity when:
⭐ The patient experiences symptoms.
Unlike a Holter:
A Holter records continuously.
An event monitor may be activated:
• By patient
• Automatically by device
Used For:
Patients with:
• Infrequent symptoms
• Occasional palpitations
• Rare episodes
❤ Memory Trick
Holter:
"Hold the whole day."
Continuous recording.
Event Monitor:
"Record the event."
Triggered by symptoms.
❤ Holter vs Event Monitor
Feature Holter Event Monitor
Recording Continuous During symptoms
Duration Usually shorter Often longer
Patient activation Usually no Often yes
Used for Frequent symptoms Infrequent symptoms
❤ 5. Telemetry Monitoring
Definition
Telemetry is:
⭐ Continuous remote monitoring of a patient's ECG.
Common Location:
🏥 Hospitals
Especially:
• Cardiac units
• ICU
• Emergency departments
How Telemetry Works
Electrodes:
↓
Transmit ECG signals
↓
Monitor station
❤ Telemetry Technician Role
May include:
✅ Watching multiple ECG monitors
✅ Identifying rhythm changes
✅ Recognizing alarms
✅ Reporting abnormalities
❤ Telemetry Is NOT:
❌ A diagnosis tool
❌ A replacement for healthcare providers
❤ Telemetry Alarms
When an alarm occurs:
The technician should:
1. Check the rhythm
2. Check the patient information
3. Notify appropriate staff
🚨 Important:
Always check the patient.
A monitor can be wrong because of:
• Loose electrodes
• Artifact
• Equipment issues
❤ Common Telemetry Problems
Lead Off Alarm
Meaning:
Electrode connection problem.
Fix:
✔ Check electrodes
✔ Replace if needed
Artifact Alarm
Possible causes:
• Movement
• Poor contact
• Electrical interference
❤ Ambulatory ECG Monitoring
Ambulatory means:
⭐ The patient can move around while being monitored.
Examples:
• Holter monitor
• Event monitor
❤ Patient Education Skills
A good EKG technician teaches patients:
✔ What the equipment does
✔ How to protect it
✔ When to report symptoms
✔ How to record events
❤ Communication During Cardiac Testing
Always:
✔ Introduce yourself
✔ Explain procedure
✔ Maintain privacy
✔ Reassure patient
✔ Encourage questions
🚨 NHA EXAM TRAPS
❌ "A Holter monitor records only when symptoms occur."
FALSE.
Holter = continuous recording.
❌ "Event monitors record continuously for 24 hours."
FALSE.
Event monitors capture episodes.
❌ "The EKG technician diagnoses rhythm abnormalities."
FALSE.
They recognize and report.
❌ "Telemetry alarms always mean the patient is in danger."
FALSE.
Could be artifact or lead problems.
❌ "Patients wearing Holter monitors should remove electrodes at night."
FALSE.
They should keep them attached.
⭐ MUST MEMORIZE COLD
🔥 Stress test = evaluates heart response to exercise
🔥 Holter = continuous portable ECG recording
🔥 Event monitor = records symptoms/events
🔥 Telemetry = continuous hospital monitoring
🔥 Always check patient, not just monitor
🔥 EKG tech recognizes and reports
🔥 Patient diaries are important for ambulatory monitoring
🧠 Self-Quiz
1. What is the purpose of a stress test?
2. Where is stress testing usually performed?
3. What does a Holter monitor record?
4. How long does a typical Holter monitor record?
5. What should patients record while wearing a Holter?
6. What is the difference between a Holter and event monitor?
7. Where is telemetry commonly used?
8. What should you check first when a monitor alarm occurs?
9. What can cause artifact on telemetry?
10. Can an EKG technician diagnose ECG findings?
💡 Abby's Memory Hacks
❤ Stress = Stress the heart
• Exercise reveals hidden problems.
❤ Holter = Holds the whole story
• Continuous recording.
❤ Event = Episode
• Records when something happens.
❤ Telemetry = Television for the heart
• Sends heart information remotely.
🎯 NHA High-Yield Facts
Know these:
⭐ Stress test monitors ECG + HR + BP
⭐ Holter monitors continuously record
⭐ Event monitors capture episodes
⭐ Telemetry is hospital-based monitoring
⭐ Artifact can mimic dangerous rhythms
⭐ Check the patient before reacting to alarms
PART 11 – ECG EQUIPMENT, MACHINE OPERATION, CALIBRATION & QUALITY CONTROL
❤ Why This Section Matters
An EKG technician must know:
✅ How the ECG machine works ✅ How to recognize equipment problems ✅ How to produce a clear tracing ✅ How to maintain accurate recordings
A perfect rhythm interpretation means nothing if the machine settings are wrong.
❤ ECG Machine Basics
An ECG machine:
1. Detects electrical signals from the heart
↓
1. Amplifies the signals
↓
1. Displays the tracing
↓
1. Records the ECG
❤ Main Parts of an ECG Machine
1. Electrodes
The adhesive sensors placed on the patient.
Purpose:
Detect electrical activity.
2. Lead Wires
Connect:
Electrodes
↓
ECG machine
3. Display Screen
Shows:
• Patient information
• ECG waveform
• Settings
4. Printer
Produces:
Paper ECG tracing
5. Keyboard/Touchscreen
Used for:
• Patient data entry
• Settings
• Recording ECGs
❤ ECG Paper Basics
ECG paper is not random.
The grid helps measure:
• Time
• Voltage
❤ ECG Paper Speed
Standard ECG paper speed:
⭐ 25 mm/second
THIS IS A BIG TEST QUESTION.
At 25 mm/sec:
One small box:
⭐ 0.04 seconds
One large box:
⭐ 0.20 seconds
🧠 Memory Trick
Small box:
"Small = 4"
0.04 seconds
Large box:
"Large = 20"
0.20 seconds
❤ Paper Speed Changes
Sometimes paper speed can be adjusted.
Examples:
50 mm/sec
Can make waveforms appear wider.
🚨 NHA Tip:
Normal ECG settings:
⭐ 25 mm/sec
⭐ 10 mm/mV
❤ Voltage Calibration (Gain)
The ECG machine must measure voltage correctly.
Standard:
⭐ 10 mm = 1 mV
This means:
A standardization mark should be:
10 small boxes tall
❤ Standardization Mark
Also called:
Calibration mark
Purpose:
Shows:
• Machine settings
• Correct voltage measurement
❤ If Calibration Is Wrong
The ECG may appear:
Too large
OR
Too small
❤ Gain Settings
If increased:
Waveforms appear larger.
If decreased:
Waveforms appear smaller.
❤ Lead Selection
The ECG machine records different views.
Examples:
Lead I
Lead II
Lead III
aVR
aVL
aVF
V1-V6
❤ Lead Wires
Each electrode connects to a specific wire.
Common colors may vary by system.
❤ Important:
Always follow:
Facility policy
AND
Machine labeling
because color systems can differ.
❤ Electrode Problems
Common problems:
Poor Adhesion
Cause:
• Sweat
• Lotion
• Hair
• Dirty skin
Fix:
✔ Clean skin
✔ Replace electrode
Dried Electrodes
Problem:
Poor electrical contact
Fix:
Replace electrodes.
❤ Equipment Troubleshooting
When ECG quality is poor:
Use:
"Check Patient → Check Placement → Check Equipment"
Step 1: Check Patient
Ask:
• Are they moving?
• Talking?
• Cold?
• Shivering?
Step 2: Check Electrodes
Look for:
• Loose stickers
• Incorrect placement
• Poor contact
Step 3: Check Equipment
Check:
• Lead wires
• Connections
• Battery
• Settings
❤ Common Equipment Problems
Lead Off Error
Meaning:
The machine cannot detect an electrode connection.
Possible causes:
• Loose electrode
• Broken wire
• Poor skin contact
Baseline Problems
Possible causes:
• Patient movement
• Poor electrode contact
• Electrical interference
Printing Problems
Possible causes:
• Empty paper
• Paper loaded incorrectly
• Printer malfunction
❤ ECG Maintenance
A technician should:
✔ Clean equipment
✔ Inspect wires
✔ Report damage
✔ Store supplies properly
✔ Follow manufacturer instructions
❤ Infection Control With Equipment
Between patients:
Clean:
✔ Electrodes (if reusable)
✔ Lead wires
✔ Machine surfaces
Follow:
Facility protocol.
❤ Quality Control (QC)
Quality control ensures:
⭐ Accurate and reliable ECG results
QC Includes:
• Equipment checks
• Calibration checks
• Maintenance logs
• Proper documentation
❤ Why QC Matters
Poor quality ECGs can lead to:
❌ Incorrect interpretation
❌ Delayed treatment
❌ Repeat testing
❤ Documentation
Document:
• Patient information
• Date/time
• Test performed
• Problems encountered
• Repeat testing if necessary
🚨 NHA EXAM TRAPS
❌ "Standard ECG paper speed is 50 mm/sec."
FALSE.
Standard:
⭐ 25 mm/sec
❌ "The calibration mark shows patient heart rhythm."
FALSE.
It shows machine settings.
❌ "A loose electrode can cause artifact."
TRUE.
❌ "Increasing gain changes the patient's heart rhythm."
FALSE.
It only changes waveform size.
❌ "ECG paper measures voltage only."
FALSE.
It measures time AND voltage.
⭐ MUST MEMORIZE COLD
🔥 Paper speed = 25 mm/sec
🔥 Small box = 0.04 sec
🔥 Large box = 0.20 sec
🔥 Standard voltage = 10 mm/mV
🔥 Calibration mark = 10 mm
🔥 Always check patient first
🔥 Artifact may come from equipment
🔥 Proper maintenance ensures accuracy
🧠 Self-Quiz
1. What is standard ECG paper speed?
2. How much time does one small box represent?
3. How much time does one large box represent?
4. What does the calibration mark show?
5. What is standard voltage calibration?
6. What causes lead-off errors?
7. What are the three troubleshooting steps?
8. Why is quality control important?
9. What should be checked if tracing is poor?
10. Does changing gain change the patient's rhythm?
💡 Abby's Memory Hacks
❤ "25 is Alive" Standard ECG speed = 25 mm/sec
❤ "4 and 20" Small box = .04 Large box = .20
❤ "10 makes it normal" 10 mm = 1 mV
❤ "Patient → Placement → Machine"
Always troubleshoot in that order.
🎯 NHA High-Yield Facts
Know these:
⭐ ECG paper measurements
⭐ Calibration
⭐ Artifact troubleshooting
⭐ Machine settings
⭐ Quality control
⭐ Equipment maintenance
———————————————————————————————————————————
PART 12 — MEDICAL TERMINOLOGY FOR EKG TECHNICIANS
❤ Why Medical Terminology Matters
As an EKG technician, you will hear healthcare providers use medical terms every day.
You need to understand:
• Patient complaints
• Physician orders
• ECG reports
• Documentation
❤ Basic Word Parts
Medical terms are often built from:
Prefix
Beginning of word.
Example:
Tachy-
Means:
Fast
Root Word
Main meaning.
Example:
Cardi
Means:
Heart
Suffix
Ending of word.
Example:
-itis
Means:
Inflammation
❤ Common Cardiac Terms
Arrhythmia / Dysrhythmia
Meaning:
⭐ Abnormal heart rhythm
Examples:
• AFib
• PVCs
• Heart blocks
Bradycardia
Break it down:
Brady = slow
Cardia = heart
Meaning:
⭐ Slow heart rate
Usually:
<60 bpm
Tachycardia
Tachy = fast
Cardia = heart
Meaning:
⭐ Fast heart rate
Usually:
100 bpm
Palpitations
Meaning:
⭐ Feeling of racing, pounding, or irregular heartbeat
Patient may say:
“My heart feels like it’s fluttering.”
Syncope
Meaning:
⭐ Fainting or temporary loss of consciousness
Often caused by:
• Reduced blood flow to brain
• Arrhythmias
• Low blood pressure
Dyspnea
Meaning:
⭐ Shortness of breath
Orthopnea
Meaning:
Difficulty breathing while lying flat.
Angina
Meaning:
⭐ Chest pain caused by reduced oxygen supply to heart muscle.
Myocardium
Meaning:
⭐ Heart muscle
Myocardial Infarction (MI)
Breakdown:
Myo = muscle
Cardial = heart
Infarction = tissue death
Meaning:
⭐ Death of heart muscle due to blocked blood supply
Ischemia
Meaning:
⭐ Reduced blood supply to tissue
Necrosis
Meaning:
⭐ Death of cells or tissue
Hypertension
Hyper = high
Tension = pressure
Meaning:
⭐ High blood pressure
Hypotension
Hypo = low
Meaning:
⭐ Low blood pressure
❤ Common Cardiovascular Conditions
Coronary Artery Disease (CAD)
Meaning:
Narrowing/blockage of coronary arteries.
Result:
⬇ Blood flow to heart
Congestive Heart Failure (CHF)
Meaning:
Heart cannot pump efficiently.
Possible symptoms:
• Swelling
• Shortness of breath
• Fatigue
Cardiomyopathy
Meaning:
Disease of the heart muscle.
Valve Disease
Problems with:
• Mitral valve
• Aortic valve
• Tricuspid valve
• Pulmonary valve
❤ Important Abbreviations
Abbreviation Meaning
ECG/EKG Electrocardiogram
HR Heart rate
BP Blood pressure
MI Myocardial infarction
CAD Coronary artery disease
CHF Congestive heart failure
PVC Premature ventricular contraction
PAC Premature atrial contraction
AFib Atrial fibrillation
SVT Supraventricular tachycardia
CPR Cardiopulmonary resuscitation
AED Automated external defibrillator
BLS Basic Life Support
❤ Symptoms Patients May Report
A patient may say:
“My heart is racing.”
Think:
Possible tachycardia/palpitations
“My chest feels heavy.”
Think:
Possible cardiac symptom requiring attention
“I feel dizzy.”
Think:
Possible rhythm problem
“I passed out.”
Think:
Syncope
🚨 NHA EXAM TRAPS
❌ Tachycardia means irregular rhythm.
FALSE.
Tachycardia only means:
FAST rate.
❌ Arrhythmia always means dangerous.
FALSE.
Some are benign.
❌ Angina means heart attack.
FALSE.
Angina = reduced oxygen supply.
MI = tissue death.
⭐ MUST MEMORIZE
🔥 Brady = slow
🔥 Tachy = fast
🔥 Cardio = heart
🔥 Angina = chest pain from reduced oxygen
🔥 MI = heart muscle death
🔥 Ischemia = reduced blood flow
🔥 Syncope = fainting
🔥 Dyspnea = shortness of breath
🧠 SELF QUIZ
1. What does tachy mean?
2. What does brady mean?
3. What is syncope?
4. What is dyspnea?
5. What is the difference between ischemia and infarction?
6. What does CAD affect?
7. What does PVC stand for?
8. What does AFib stand for?
9. What does CHF mean?
10. What does ECG stand for?
PART 13 — CARDIOVASCULAR ANATOMY DEEP DIVE
❤ The Heart: The Basics
The heart is a muscular organ responsible for:
⭐ Pumping blood throughout the body
It provides:
• Oxygen
• Nutrients
• Waste removal
❤ Location of the Heart
The heart is located in the:
⭐ Mediastinum
(the central area of the chest)
Between:
• Right and left lungs
Behind:
• Sternum
❤ Layers of the Heart Wall
The heart has three main layers:
1. Epicardium
Outer layer.
Also called:
Visceral pericardium
2. Myocardium
⭐ Middle muscular layer
This is the part that contracts.
Most important for ECGs.
3. Endocardium
Inner lining.
Covers:
• Chambers
• Valves
🧠 Memory Trick
Epi = Exterior
Myo = Muscle
Endo = Inside
❤ Chambers of the Heart
The heart has FOUR chambers.
Two atria:
⬆ Receiving chambers
Two ventricles:
⬇ Pumping chambers
❤ Right Atrium
Receives:
⭐ Deoxygenated blood
From:
• Superior vena cava
• Inferior vena cava
Blood then moves to:
↓
❤ Right Ventricle
Purpose:
Pumps blood to the lungs.
Through:
⭐ Pulmonary artery
❤ Left Atrium
Receives:
⭐ Oxygen-rich blood
From lungs through:
Pulmonary veins
Blood moves to:
↓
❤ Left Ventricle
The strongest chamber.
Purpose:
Pumps oxygenated blood to the body.
Through:
⭐ Aorta
🧠 Memory Trick
RIGHT = Returns blood from body
LEFT = Leaves blood to body
❤ Blood Flow Pathway
MEMORIZE THIS:
Body
↓
Superior/Inferior Vena Cava
↓
Right Atrium
↓
Tricuspid Valve
↓
Right Ventricle
↓
Pulmonary Valve
↓
Pulmonary Artery
↓
Lungs
↓
Pulmonary Veins
↓
Left Atrium
↓
Mitral Valve
↓
Left Ventricle
↓
Aortic Valve
↓
Aorta
↓
Body
🧠 Easy Memory Trick:
"Try Pulling My Aorta"
T = Tricuspid
P = Pulmonary
M = Mitral
A = Aortic
These are the four valves.
❤ Heart Valves
Valves prevent:
⭐ Backflow of blood
1. Tricuspid Valve
Location:
Right atrium → Right ventricle
2. Pulmonary Valve
Location:
Right ventricle → Pulmonary artery
3. Mitral Valve
Also called:
Bicuspid valve
Location:
Left atrium → Left ventricle
4. Aortic Valve
Location:
Left ventricle → Aorta
❤ Cardiac Cycle
The cardiac cycle describes:
⭐ One complete heartbeat
Includes:
1. Diastole
2. Systole
❤ Diastole
Meaning:
Heart relaxation
During diastole:
The chambers fill with blood.
❤ Systole
Meaning:
Heart contraction
During systole:
The ventricles pump blood out.
🧠 Memory Trick:
Systole = Squeeze
The heart squeezes.
❤ Electrical Activity vs Mechanical Activity
Important concept:
The ECG shows:
⭐ Electrical activity
NOT:
Actual pumping.
Example:
An ECG can show electrical activity…
but the heart may not pump effectively.
❤ Depolarization vs Repolarization
THIS IS A BIG EKG CONCEPT.
Depolarization
Meaning:
⭐ Electrical activation
The heart muscle cells become stimulated.
Usually leads to:
Contraction.
Repolarization
Meaning:
⭐ Electrical recovery/resetting
The cells prepare for the next heartbeat.
ECG Connection:
P Wave
Atrial depolarization
↓
Atria contract
QRS Complex
Ventricular depolarization
↓
Ventricles contract
T Wave
Ventricular repolarization
↓
Ventricles recover
❤ Coronary Arteries
The heart muscle itself needs blood supply.
The coronary arteries provide oxygen.
❤ Right Coronary Artery (RCA)
Supplies:
• Right ventricle
• Inferior heart
• SA node (often)
• AV node (often)
❤ Left Main Coronary Artery
Divides into:
Left Anterior Descending (LAD)
Supplies:
• Anterior wall
• Septum
Left Circumflex (LCX)
Supplies:
• Lateral wall
❤ Why Coronary Arteries Matter for EKGs
Blocked artery:
↓
Reduced oxygen
↓
Heart injury
↓
ECG changes
Example:
Blocked RCA:
Possible:
Inferior MI
Leads:
II, III, aVF
Blocked LAD:
Possible:
Anterior MI
Leads:
V3-V4
❤ Septum
The septum separates:
Right side
from
Left side
Septal leads:
⭐ V1–V2
❤ Cardiac Output
Cardiac output means:
⭐ Amount of blood pumped by the heart per minute
Formula:
Heart Rate × Stroke Volume
Example:
Heart rate increases…
but if pumping becomes weak:
Cardiac output may still decrease.
❤ Stroke Volume
Amount of blood pumped:
⭐ With each heartbeat
Affected by:
• Heart strength
• Blood volume
• Resistance
❤ Ejection Fraction (EF)
Measures:
⭐ How much blood leaves the left ventricle during contraction
Normal EF:
Approximately:
⭐ 55–70%
Low EF may suggest:
Heart failure.
🚨 NHA EXAM TRAPS
❌ "The ECG measures contraction."
FALSE.
It measures electrical activity.
❌ "The right ventricle pumps oxygenated blood."
FALSE.
Right ventricle pumps blood to lungs.
❌ "The left ventricle is thinner than the right."
FALSE.
Left ventricle is thickest because it pumps to the entire body.
❌ "The mitral valve is on the right side."
FALSE.
Mitral = left side.
⭐ MUST MEMORIZE COLD
🔥 Right heart → lungs
🔥 Left heart → body
🔥 Myocardium = muscle layer
🔥 Depolarization = activation
🔥 Repolarization = recovery
🔥 QRS = ventricular depolarization
🔥 T wave = ventricular repolarization
🔥 LAD = anterior/septal
🔥 RCA = often inferior
🔥 LCX = lateral
🧠 SELF QUIZ
1. What is the main function of the heart?
2. Which chamber pumps blood to the lungs?
3. Which chamber pumps blood to the body?
4. What valve is between the left atrium and left ventricle?
5. What does systole mean?
6. What does diastole mean?
7. What does the ECG measure?
8. What does the QRS represent?
9. Which leads view the septum?
10. Which coronary artery is associated with anterior MI?
💡 ABBY MEMORY HACKS
❤ "Right = Respiratory" Right side goes to lungs.
❤ "Left = Leaving the heart" Left ventricle sends blood everywhere.
❤ "Myo = Muscle"
❤ "Squeeze = Systole"
❤ "QRS = Quick Ventricular Squeeze"
PART 14 — PATIENT COMMUNICATION & PROFESSIONALISM
❤ Why Communication Matters
An EKG technician is often one of the first healthcare workers a patient interacts with.
Your job is not only technical.
You must make the patient feel:
✅ Safe ✅ Respected ✅ Comfortable ✅ Informed
A calm patient = better ECG tracing.
❤ The Patient Interaction Process
Step 1: Introduce Yourself
Example:
“Hello, my name is Abby. I’m the EKG technician who will be performing your test today.”
Step 2: Verify Patient Identity
Use:
⭐ Two patient identifiers
Examples:
• Full name
• Date of birth
• Medical record number
🚨 NEVER use:
❌ Room number alone
❌ Bed number alone
❤ Step 3: Explain the Procedure
Tell the patient:
• What the test does
• What they will feel
• How long it takes
Example:
“This test records the electrical activity of your heart. You will feel the electrodes stick to your skin, but the test does not hurt.”
❤ Step 4: Provide Privacy
During ECG placement:
The patient may need to expose:
• Chest
• Ankles
• Wrists
Maintain dignity.
Use:
✔ Drapes
✔ Curtains
✔ Proper positioning
❤ Step 5: Encourage Questions
Patients may feel nervous.
Answer calmly.
If you do not know:
Say:
“I’ll find the appropriate person to answer that.”
❤ Communication With Different Patients
Anxious Patient
Use:
✔ Calm voice
✔ Simple explanations
✔ Reassurance
Avoid:
❌ Rushing
Hearing-Impaired Patient
Use:
✔ Face the patient
✔ Speak clearly
✔ Use written communication if needed
Language Barrier
Use:
✔ Interpreter services
Avoid:
❌ Using children as translators
Elderly Patients
Consider:
• Hearing difficulty
• Vision problems
• Mobility issues
❤ Professional Behavior
A professional EKG technician:
✔ Arrives prepared
✔ Maintains confidentiality
✔ Treats everyone respectfully
✔ Communicates clearly
✔ Works as a team
❤ Therapeutic Communication
Use:
✔ Open-ended questions
Example:
“How are you feeling today?”
Avoid:
❌ Arguing
❌ Judgmental comments
❌ Giving personal opinions
🚨 NHA EXAM TRAPS
❌ "Use room number to identify patient."
FALSE.
Use two identifiers.
❌ "Tell the patient their ECG diagnosis."
FALSE.
Technicians do not diagnose.
❌ "Skip explaining the test if the patient seems calm."
FALSE.
Always explain.
⭐ MUST MEMORIZE
🔥 Two identifiers
🔥 Protect privacy
🔥 Explain procedure
🔥 Stay within scope of practice
🔥 Communicate professionally
🧠 SELF QUIZ
1. How many identifiers should be used?
2. Can an EKG technician diagnose?
3. What should you do before touching a patient?
4. Why is patient privacy important?
5. What is therapeutic communication?
PART 15 — INFECTION CONTROL & PATIENT SAFETY
❤ Why Infection Control Matters
Healthcare workers interact with many patients every day.
Proper infection control prevents:
• Spread of bacteria
• Spread of viruses
• Healthcare-associated infections (HAIs)
❤ The Chain of Infection
Infection spreads through a chain.
The six links:
1. Infectious agent
2. Reservoir
3. Portal of exit
4. Mode of transmission
5. Portal of entry
6. Susceptible host
🧠 How Do We Break the Chain?
We interrupt transmission by using:
✅ Hand hygiene ✅ PPE ✅ Cleaning equipment ✅ Proper disposal ✅ Safe practices
❤ Standard Precautions
Standard precautions are used:
⭐ With EVERY patient
Regardless of diagnosis.
Includes:
✔ Hand hygiene
✔ Gloves when needed
✔ Safe handling of equipment
✔ Protection from body fluids
❤ Hand Hygiene
The #1 way to prevent infection spread.
When Should You Perform Hand Hygiene?
Before:
✔ Touching patient
✔ Performing procedure
✔ Applying electrodes
After:
✔ Patient contact
✔ Removing gloves
✔ Contact with equipment
❤ Soap and Water vs Hand Sanitizer
Use Soap and Water When:
✔ Hands are visibly dirty
✔ After certain infectious exposures
Alcohol-Based Hand Sanitizer
Used when:
✔ Hands are not visibly soiled
❤ Personal Protective Equipment (PPE)
PPE protects:
YOU
and
THE PATIENT
Types of PPE
Gloves
Used when:
• Contact with body fluids possible
• Contact with non-intact skin
Remember:
Gloves DO NOT replace hand hygiene.
Gowns
Protect clothing.
Used when:
• Splash risk
• Contact with infectious materials
Masks
Protect against:
• Droplets
• Respiratory exposure
Eye Protection
Used when:
Risk of splashes to eyes.
❤ Putting On PPE (Donning)
Typical order:
1. Gown
2. Mask/respirator
3. Eye protection
4. Gloves
❤ Removing PPE (Doffing)
Gloves are usually removed first because they are most contaminated.
❤ Cleaning ECG Equipment
EKG equipment touches many patients.
Clean:
✔ Lead wires
✔ Electrodes (if reusable)
✔ Machine surfaces
✔ Patient contact areas
❤ Disposable vs Reusable Electrodes
Disposable:
⭐ Used once
Then discarded.
Reusable:
Must be:
✔ Cleaned
✔ Disinfected
According to policy.
❤ Sharps Safety
EKG technicians may not usually handle many sharps, but must understand safety.
Never:
❌ Recap used needles
❌ Throw sharps into regular trash
Dispose in:
⭐ Sharps container
❤ Bloodborne Pathogens
Examples:
• Hepatitis B
• Hepatitis C
• HIV
Exposure can occur through:
• Blood
• Body fluids
• Needlestick injuries
❤ If Exposure Occurs
Follow facility protocol:
1. Wash area immediately
2. Report exposure
3. Seek medical evaluation
❤ Patient Safety During ECG
Before procedure:
✔ Verify identity
✔ Explain test
✔ Ensure privacy
✔ Check environment
During procedure:
✔ Monitor patient condition
✔ Keep patient safe
✔ Avoid unnecessary exposure
After:
✔ Remove electrodes properly
✔ Help patient sit up slowly if needed
✔ Document appropriately
❤ Fall Prevention
Some patients may become dizzy.
Safety steps:
✔ Keep bed low
✔ Assist patient if needed
✔ Do not rush standing
❤ Electrical Safety
ECG equipment uses electrical signals.
Safety:
✔ Inspect wires
✔ Keep equipment dry
✔ Report damaged equipment
🚨 NHA EXAM TRAPS
❌ "Standard precautions are only used with infectious patients."
FALSE.
Used with EVERY patient.
❌ "Gloves replace handwashing."
FALSE.
Hand hygiene is still required.
❌ "Clean ECG equipment only when visibly dirty."
FALSE.
Clean according to protocol between patients.
❌ "Patient privacy is optional during ECG placement."
FALSE.
Privacy is always required.
⭐ MUST MEMORIZE COLD
🔥 Standard precautions = every patient
🔥 Hand hygiene = #1 infection prevention
🔥 Gloves do not replace hand washing
🔥 Clean equipment between patients
🔥 PPE protects patient and worker
🔥 Report exposures immediately
🧠 SELF QUIZ
1. What are standard precautions?
2. When should hand hygiene occur?
3. Do gloves replace handwashing?
4. What PPE protects clothing?
5. What should happen after exposure to blood?
6. Why is equipment cleaning important?
7. What is the chain of infection?
8. When are standard precautions used?
9. How can falls be prevented?
10. Why should equipment wires be inspected?
💡 ABBY MEMORY HACKS
🧼 "Clean hands save lives."
🧤 "Gloves go on, germs stay gone."
🛡 "Standard = EVERYBODY."
⚡ "Broken wire? Don’t use it."
PART 16 — LEGAL & ETHICAL RESPONSIBILITIES
❤ Why This Matters
An EKG technician works with:
• Private health information
• Vulnerable patients
• Medical records
• Diagnostic equipment
You must understand your responsibilities.
⚖ Scope of Practice
Definition:
Scope of practice means:
⭐ The duties and responsibilities you are trained and legally allowed to perform.
EKG Technician CAN:
✅ Prepare patients
✅ Apply electrodes
✅ Perform ECG tests
✅ Obtain clear tracings
✅ Recognize abnormalities
✅ Report findings
✅ Maintain equipment
EKG Technician CANNOT:
❌ Diagnose conditions
❌ Interpret ECGs independently (unless trained/authorized by role)
❌ Prescribe treatment
❌ Tell patients they are having a heart attack
🧠 NHA Rule:
"Recognize → Record → Report"
NOT:
"Diagnose → Explain → Treat"
⚖ HIPAA (Health Insurance Portability and Accountability Act)
HIPAA protects:
⭐ Patient health information (PHI)
Examples of PHI:
• Name
• Medical record number
• Diagnosis
• Test results
• Birth date
• Medical history
❤ Protecting Patient Privacy
You should:
✅ Speak quietly about patients
✅ Secure records
✅ Log out of computers
✅ Avoid discussing patients publicly
Never:
❌ Discuss patients in elevators
❌ Share information with friends
❌ Leave charts open
⚖ Patient Confidentiality
Confidentiality means:
⭐ Keeping patient information private.
Example:
A coworker asks:
“What did the patient’s ECG show?”
If they are not involved in care:
You should not share.
⚖ Informed Consent
Consent means:
The patient agrees to a procedure after receiving information.
Before an ECG:
The patient should understand:
• What the procedure is
• What will happen
• Any concerns/questions
❤ Patient Rights
Patients have the right to:
✅ Privacy
✅ Respect
✅ Information
✅ Refuse care
✅ Ask questions
❤ If a Patient Refuses an ECG
The technician should:
1. Respect the decision
2. Notify appropriate healthcare provider
3. Document refusal according to policy
⚖ Documentation
Medical documentation must be:
⭐ Accurate
⭐ Complete
⭐ Objective
⭐ Timely
Good Documentation:
Example:
"12-lead ECG completed at 10:15 AM. Patient tolerated procedure well."
Poor Documentation:
❌ "Patient was annoying."
Not objective.
⚖ Incident Reports
An incident report is completed when:
• Injury occurs
• Equipment malfunction causes concern
• Unexpected event happens
Important:
Incident reports are:
NOT part of the patient chart.
⚖ Negligence
Negligence means:
⭐ Failure to provide reasonable care.
Four elements:
Duty
You had responsibility.
↓
Breach
You failed to act properly.
↓
Harm
Patient was affected.
↓
Cause
Your action/inaction caused harm.
Examples of Negligence:
❌ Wrong patient tested
❌ Failure to report dangerous findings
❌ Improper equipment cleaning
❌ Leaving patient unsafe
⚖ Malpractice
Malpractice:
Professional negligence by a trained healthcare worker.
⚖ Ethics
Ethics means:
Doing what is morally right.
An ethical EKG technician:
✅ Treats patients with dignity
✅ Maintains honesty
✅ Protects privacy
✅ Provides safe care
❤ Professional Boundaries
Maintain appropriate relationships.
Avoid:
❌ Sharing personal problems
❌ Accepting inappropriate gifts
❌ Becoming overly involved
🚨 NHA EXAM TRAPS
❌ "EKG technicians diagnose arrhythmias."
FALSE.
They recognize and report.
❌ "Patient information can be shared with anyone who asks."
FALSE.
Only authorized individuals.
❌ "Incident reports belong in the patient chart."
FALSE.
They are separate.
❌ "A patient cannot refuse a procedure."
FALSE.
Patients have rights.
⭐ MUST MEMORIZE COLD
🔥 HIPAA = protects patient information
🔥 Scope = what you are allowed to do
🔥 Recognize, record, report
🔥 Patients have rights
🔥 Document facts, not opinions
🔥 Never diagnose
🔥 Privacy always matters
🧠 SELF QUIZ
1. What does HIPAA protect?
2. Can an EKG technician diagnose an MI?
3. What does scope of practice mean?
4. What should you do if a patient refuses testing?
5. What makes documentation professional?
6. What is negligence?
7. What is confidentiality?
8. Where are incident reports kept?
9. Who can access PHI?
10. What are the three R’s of EKG responsibility?
💡 ABBY MEMORY HACKS
⚖ "HIPAA = Hide Information Protected Against Access"
🩺 "Techs don’t diagnose, techs notify."
📝 "If it wasn’t documented, it wasn’t done."
🚨 "See it → Save the tracing → Send it up."
RHYTHM DETECTIVE MODE
The NHA is not expecting you to be a cardiologist. They want to know:
✅ Can you recognize normal vs abnormal? ✅ Can you identify major rhythms? ✅ Can you recognize dangerous findings? ✅ Do you know when to report?
Your rhythm interpretation formula:
❤ RATE → RHYTHM → P WAVES → PR INTERVAL → QRS
EVERY TIME.
📚 NHA CERTIFIED EKG TECHNICIAN (CET) MASTER STUDY GUIDE
❤ PART 17 — RHYTHM PRACTICE DRILLS
🫀 The Rhythm Analysis Checklist
When looking at any ECG strip:
Ask yourself:
1⃣ What is the Rate?
Is it:
⬇ Slow?
Normal?
⬆ Fast?
2⃣ Is the Rhythm Regular?
Look at:
R-R intervals
Are they:
Equal?
OR
Unequal?
3⃣ Are P Waves Present?
Ask:
• Is there a P wave before every QRS?
• Are they the same shape?
4⃣ Is the PR Interval Normal?
Normal:
⭐ 0.12–0.20 seconds
5⃣ Is the QRS Narrow or Wide?
Normal:
⭐ Less than 0.12 seconds
🧠 Rhythm Detective Shortcut:
"P-QRS-T"
If everything follows normally:
Think sinus rhythm.
❤ RHYTHM #1 — Normal Sinus Rhythm (NSR)
Rate:
60–100 bpm
Rhythm:
Regular
P Waves:
✅ Present
✅ One before every QRS
PR:
Normal
0.12–0.20
QRS:
Narrow
Memory:
❤ "The heart is following the rules."
❤ RHYTHM #2 — Sinus Bradycardia
Rate:
⬇ Less than 60 bpm
Everything else:
NORMAL
Example:
Rate: 50
P waves: normal
PR: normal
QRS: normal
Possible causes:
• Athletes
• Sleep
• Medications
• Increased vagal tone
NHA Point:
Slow does NOT automatically mean dangerous.
❤ RHYTHM #3 — Sinus Tachycardia
Rate:
⬆ Greater than 100 bpm
Everything else:
NORMAL
Possible causes:
• Exercise
• Stress
• Fever
• Pain
• Anxiety
Memory:
❤ "The sinus node is just running faster."
❤ RHYTHM #4 — Sinus Arrhythmia
Rate:
Usually normal
Rhythm:
❌ Irregular
Key:
Changes with breathing
Example:
Heart speeds up when inhaling.
Slows when exhaling.
❤ RHYTHM #5 — Premature Atrial Contraction (PAC)
A PAC is:
⭐ An early heartbeat that starts in the atria.
Look for:
✅ Early beat
✅ Abnormal P wave
✅ Narrow QRS
Think:
"The atria jumped the line."
❤ RHYTHM #6 — Atrial Flutter
Cause:
Rapid atrial activity.
Key Finding:
⭐ Saw-tooth waves
Rate:
Atrial:
250–350 bpm
Ventricular rhythm:
May be regular.
Memory:
🦷 "Flutter has teeth."
❤ RHYTHM #7 — Atrial Fibrillation (AFib)
THE BIG ONE.
Key findings:
🚨 No clear P waves
🚨 Irregularly irregular rhythm
🚨 Chaotic baseline
Common concern:
Blood clot risk.
Memory:
"AFib = Absolutely Freaking Irregular" 😂
❤ RHYTHM #8 — Supraventricular Tachycardia (SVT)
Origin:
Above ventricles.
Findings:
🔥 Very fast rate
🔥 Regular rhythm
🔥 Narrow QRS
Rate:
Usually:
150–250 bpm
Patient may experience:
• Palpitations
• Dizziness
• Chest discomfort
❤ RHYTHM #9 — Junctional Rhythm
Origin:
AV junction
Rate:
40–60 bpm
Findings:
P waves:
❌ Missing
OR
⬇ Inverted
OR
Hidden
QRS:
Usually narrow
Memory:
"The AV node takes over."
❤ RHYTHM #10 — Premature Ventricular Contraction (PVC)
Origin:
Ventricles
Findings:
💥 Early beat
💥 Wide QRS
💥 No normal P wave before it
Memory:
"PVC = Ventricles fire early."
❤ RHYTHM #11 — Ventricular Tachycardia (VT)
DANGEROUS RHYTHM 🚨
Findings:
🔥 Fast
🔥 Wide QRS
🔥 Usually regular
Rate:
100–250 bpm
May cause:
• Low blood pressure
• Loss of consciousness
• Cardiac arrest
❤ RHYTHM #12 — Ventricular Fibrillation (VFib)
Emergency.
Findings:
🚨 Chaotic electrical activity
🚨 No organized QRS
🚨 No pulse
Treatment:
CPR + defibrillation
❤ RHYTHM #13 — Asystole
The flatline.
Findings:
No electrical activity.
Treatment:
CPR
NOT defibrillation.
❤ RHYTHM COMPARISON TABLE
Rhythm Rate Key Clue
NSR 60-100 Normal P-QRS-T
Brady <60 Slow sinus
Tachy >100 Fast sinus
PAC Normal Early atrial beat
Flutter Fast Saw teeth
AFib Variable Irregularly irregular
SVT 150-250 Very fast narrow
Junctional 40-60 Missing/inverted P
PVC Variable Wide early beat
VT 100-250 Fast wide
VFib — Chaotic
Asystole — Flatline
🚨 NHA RHYTHM TRAPS
❌ "AFib is regularly irregular."
FALSE.
AFib:
⭐ Irregularly irregular
❌ "PVCs have narrow QRS complexes."
FALSE.
PVCs:
⭐ Wide QRS
❌ "Asystole gets shocked."
FALSE.
No pulse → CPR protocol.
❌ "SVT is a ventricular rhythm."
FALSE.
SVT starts above ventricles.
⭐ MUST KNOW COLD
🔥 Normal = P before every QRS
🔥 AFib = no P + irregularly irregular
🔥 Flutter = saw teeth
🔥 PVC = wide ugly early beat
🔥 VT = fast wide dangerous
🔥 VFib = chaotic/no pulse
🔥 Asystole = flatline
🧠 SELF QUIZ
1. What is normal sinus rhythm rate?
2. What makes AFib different from flutter?
3. What does a PVC look like?
4. Which rhythm has saw-tooth waves?
5. Which rhythm is a medical emergency?
6. What rhythm is irregularly irregular?
7. What rhythm has a flatline?
8. What makes SVT different from VT?
9. What is the QRS width of PVCs?
10. What rhythm starts in the AV junction?
💡 ABBY MEMORY HACKS
🦷 Flutter = Teeth
💥 PVC = Popcorn Ventricular Contraction (early pop)
⚡ VT = Very Terrifying
🌪 VFib = Violent Fibrillation
📏 Wide = Think ventricular
PART 18 — ECG CALCULATIONS & MEASUREMENTS
❤ Why ECG Measurements Matter
An EKG technician must understand:
• Heart rate
• Timing
• Intervals
• Waveform measurements
These measurements help healthcare providers evaluate cardiac function.
❤ ECG Paper Basics (REVIEW)
Standard ECG settings:
⭐ Paper speed: 25 mm/sec
⭐ Voltage: 10 mm = 1 mV
❤ ECG Grid
ECG paper contains:
Small Boxes
Each small box:
⭐ 0.04 seconds
Large Boxes
One large box contains:
5 small boxes
Therefore:
⭐ 0.20 seconds
🧠 Memory Trick
Small:
4
Large:
20
❤ Calculating Heart Rate
There are three common methods:
1. 300 Method
2. 1500 Method
3. 6-Second Method
❤ Method #1 — The 300 Method
Used for:
⭐ Regular rhythms
Formula:
300 ÷ number of large boxes between R waves
Example:
R-R interval:
4 large boxes
300 ÷ 4
= 75 bpm
Memorize:
Large boxes:
1 = 300 bpm
2 = 150 bpm
3 = 100 bpm
4 = 75 bpm
5 = 60 bpm
6 = 50 bpm
🧠 300 Method Trick
Think:
"How many big boxes?"
Then:
300 ÷ boxes
❤ Method #2 — 1500 Method
Used for:
⭐ Very accurate measurement
⭐ Regular rhythms
Formula:
1500 ÷ number of small boxes between R waves
Example:
R-R interval:
20 small boxes
1500 ÷ 20
= 75 bpm
🧠 Memory:
Small boxes = 1500
Large boxes = 300
❤ Method #3 — 6-Second Method
Used for:
⭐ Irregular rhythms
Steps:
1. Count QRS complexes in 6 seconds
2. Multiply by 10
Example:
7 QRS complexes in 6 seconds
7 × 10
= 70 bpm
🧠 Memory Trick:
"6 seconds × 10 gets you one minute."
❤ Determining Rhythm Regularity
Look at:
⭐ R-R intervals
Regular:
Same distance between R waves
Irregular:
Different spacing between R waves
❤ Measuring the PR Interval
The PR interval represents:
⭐ Time from atrial depolarization to ventricular depolarization
Measured:
Beginning of P wave
↓
Beginning of QRS
Normal:
⭐ 0.12–0.20 seconds
On ECG paper:
3–5 small boxes
🚨 Abnormal PR
Long PR:
May indicate:
AV conduction delay
Example:
First-degree AV block
Short PR:
May suggest:
Abnormal conduction pathways
❤ Measuring QRS Duration
QRS represents:
⭐ Ventricular depolarization
Normal:
⭐ Less than 0.12 seconds
On paper:
Less than 3 small boxes
🚨 Wide QRS
May indicate:
• Ventricular rhythm
• Bundle branch problems
• Abnormal conduction
❤ Measuring QT Interval
QT interval represents:
⭐ Total time for ventricular depolarization + repolarization
Measured:
Beginning of QRS
↓
End of T wave
QT is affected by:
❤ Heart rate
A prolonged QT can increase risk of dangerous rhythms.
❤ ST Segment Measurement
The ST segment is evaluated for:
• Elevation
• Depression
ST Elevation:
Possible:
⭐ Myocardial injury
ST Depression:
Possible:
⭐ Ischemia
❤ Axis Basics (NHA Level)
The electrical axis describes:
⭐ The general direction of electrical activity through the heart.
For the NHA:
Know:
Lead II is often used because it usually shows a clear rhythm.
❤ Counting Boxes Practice
Example:
A rhythm has:
5 large boxes between R waves.
Heart rate:
300 ÷ 5
= 60 bpm
Example:
A rhythm has:
3 large boxes.
Heart rate:
300 ÷ 3
= 100 bpm
Example:
A rhythm has:
30 small boxes.
Heart rate:
1500 ÷ 30
= 50 bpm
❤ Rhythm Calculation Practice
Question 1
R-R interval:
2 large boxes
Heart rate?
300 ÷ 2
= 150 bpm
Question 2
R-R interval:
6 large boxes
Heart rate?
300 ÷ 6
= 50 bpm
Question 3
8 QRS complexes in 6 seconds
Heart rate?
8 × 10
= 80 bpm
❤ NHA Calculation Traps
❌ "Use the 300 method for irregular rhythms."
FALSE.
Use:
⭐ 6-second method
❌ "One small box equals 0.20 seconds."
FALSE.
Small:
⭐ 0.04 seconds
❌ "Normal QRS is longer than 0.12 seconds."
FALSE.
Normal:
⭐ Less than 0.12 seconds
❌ "PR interval measures ventricular contraction."
FALSE.
PR measures:
Atrial-to-ventricular conduction
⭐ MUST MEMORIZE COLD
🔥 Paper speed = 25 mm/sec
🔥 Small box = 0.04 sec
🔥 Large box = 0.20 sec
🔥 PR = 0.12–0.20 sec
🔥 QRS <0.12 sec
🔥 300 method = regular rhythms
🔥 1500 method = small boxes
🔥 6-second method = irregular rhythms
🔥 ST elevation = injury concern
🔥 ST depression = ischemia concern
🧠 SELF QUIZ
1. What is one small box?
2. What is one large box?
3. What method is used for irregular rhythms?
4. What is the normal PR interval?
5. What does the QRS represent?
6. What does a wide QRS suggest?
7. What is the formula for the 300 method?
8. What is the formula for the 1500 method?
9. What does ST elevation suggest?
10. What does ST depression suggest?
💡 ABBY MEMORY HACKS
📏 "Small 4, Large 20"
Small box = .04 Large box = .20
➗ "Big boxes? 300."
➗ "Tiny boxes? 1500."
⏱ "Irregular? Six seconds kicks."
🫀 "PR = Preparation Route"
Electrical signal preparing ventricles.