ekg

purpose of an EKG

records the electrical activity of the heart

Normal electrical conduction pathway

1. SA node

2. Atrial pathway

3. AV node

4. Bundle of HIs

5. Right & left bundle branches

6. Purkinje fibers

Where is the SA node located

Right atrium

What is the SA node

The heart’s natural pacemaker

What does the AV node do

delays impulses briefly, allowing time for atria to contract and ventricles to fill with blood

What is the Bundle of His

Electrical connection between atria and ventricles

What do the left and right bundle branches do

carries impulses to ventricles

What do the purkinje fibers do

Rapidly spread impulses from Bundle of His to the ventricles

ECG paper speed

25 mm/sec

A small box is how many seconds?

0.04

One large box is how many small boxes?

5

One large box is how many seconds?

1

There should be one ____ wave before every _______

P; QRS complex

The P wave represents…

atrial depolarization (contracting)

An absent P wave suggests…

Atrial rhythm problems

The PR interval is normally how long?

0.12-0.20 seconds

A prolonged PR interval represents…

AV block

The PR interval represents…

The time it takes for the electrical impulse to travel from the atria through the AV node, and into the ventricles

What does the PR segment represent

The delay in electrical impulse conduction through the AV node

The PR segment is usually…

flat

What is the PR segment

The flat line between the end of the P wave and beginning of QRS complex

The QRS complex represents…

ventricular depolarization (leading to ventricular contraction)

Ventricular contraction occurs just after the _______ and during the _______

QRS complex; ST segment

Normal duration of the QRS complex

less than 0.12 sec

The J point represents

It marks where the QRS complex ends and the ST segment begins

The ST segment is normally…

flat

The ST segment represents…

The period when the ventricles are fully depolarized and actively contracting

The T wave represents…

Ventricular repolarization (beginning of relaxation)

The U wave represents….

repolarization of the purkinje fibers

The U wave follows the …..

T wave

The T wave follows…

Each QRS complex

The QT interval represents…

One complete ventricular cycle (depolarization & repolarization)

The QT interval starts at the _____ and ends with the _____

QRS; T

Qualities of a normal sinus rhythm

1. Rate: 60-100 bpm

2. P wave before every QRS

3. QRS is less than 0.12 sec

4. PR interval: 0.12 - 0.20 sec

5. Regular rhythm

Sinus bradycardia rate

Less than 60 bpm

True or false: sinus bradycardia has normal P waves

True

Sinus tachycardia rate

greater than 100 bpm

Causes of sinus tachycardia

• Fever

• Pain

• Anxiety

• Dehydration

• Hypoxia

Atrial fibrillation

Chaotic, disorganized heart rhythm where the atria quiver instead of contract

Characteristics of atrial fibrillation

• Chaotic

• No identifiable P wave

• Narrow QRS complexes

• Irregular RR intervals

• Blood can pool in atria (↑ risk of clot formation)

Atrial flutter

Rapid but organized atrial rhythm, where the atria contracts but too fast to fill effectively

Characteristics of atrial flutter

• Organized

• Regular RR intervals

Ventricular tachycardia characteristics

• Rate: 100+ bpm

• Wide QRS complexes (greater than 0.12 sec)

• No P waves

Ventricular fibrillation characteristics

• Ventricles quiver instead of contract

• No cardiac output

• No P waves

• No QRS complexes

• Chaotic/irregular

Why should you not defibrillate during asystole

defibrillators work by resetting electrical activity- but in asystole, there is no electrical activity to reset- CPR and epinephrine instead

First degree atrioventricular block

delay in conduction from SA node to the AV node

PR interval in first degree atrioventricular block is typically….

Greater than 0.20 seconds

Second degree atrioventricular block, type 1 is also known as…

Wenckebach

Second degree atrioventricular block, type 1 characteristics

• Blocked impulses from AV node to ventricles

• PR interval gets progressively longer, then one QRS is dropped

Second degree atrioventricular block, type 2 characteristics

• Classic heart block

• AV node selectively blocks specific impulses

• PR interval stays consistent, then sudden QRS complex

• No warning or slowing

Third degree atrioventricular block characteristics

• Complete heart block

• Atria and ventricles beat independently

• No pattern

• Random PR intervals

• No relationship between P and QRS

• All electrical impulses that original above the ventricles are blocked

Right bundle branch block

The left ventricle contracts first, then the right ventricle contracts late

Left bundle branch block

The right ventricle contracts first, then the left ventricle contracts late

What is more serious, right bundle branch block or left bundle branch block?

Left bundle branch block

Chain of infection order

1. Infectious agent (germ)

2. Reservoir (where it livers)

3. Portal of exit (how it leaves)

4. Mode of transmission (how it travels)

5. Portal of entry (how it gets in)

6. Susceptible host (person at risk to getting sick)

Normal BP range

100-140 / 60-90

Normal HR range

60-100

Holter monitor

Portable, wearable device that continuously records heart’s electrical activity for 24 hours

How many leads are used for holter monitor

3-5

Event recorder

Wearable, portable device that monitors and records heart’s electrical activity over days, weeks, or longer

How to calculate max HR

220 - patient’s age

How to calculate target HR

Max HR x 0.7

What is the segment highlighted in red

P wave

A tall P wave indicates

Right atrial enlargement

A wide P wave indicates

left atrial enlargement

A prolonged PR interval indicates

Delayed conduction from atria to ventricles (1st degree AV block)

What segment is this (the blue bracket)

PR interval

PR segment depression indicates

pericarditis

What segment is this

PR segment

What does a wide QRS complex indicate

bundle branch block or ventricular dysfunction

What is the green segment

QRS complex

What does an elevated j point indicate

Early depolarization or MI

What does a depressed j point indicate

ischemia

What is the black arrow pointing at

J point

ST segment elevation indicates

AMI

ST segment depression indicates

myocardial ischemia

What is the highlighted section

ST segment

Inverted T wave indicates

myocardial ischemia

Elevated t wave indicates

hyperkalemia

Hyperkalemia

Increased potassium levels

Depressed T wave indicates

Hypokalemia

Hypokalemia

Low potassium levels

What is the highlighted section

T wave

A prominent U wave indicates…

Hypokalemia

What is the arrow pointing to

U wave

Irregular PP interval indicates

atrial dysrhythmia

what segment is this (bracket)

RR interval

what does an irregular RR interval indicate

atrial fibrillation

Prolonged QT interval indicates

delayed ventricular repolarization (triggers torsades de pointes)

torsades de pointes

type of life threatening ventricular tachycardia

what segment is this

QT interval

epicardium

outermost layer of the heart, made of connective tissue

myocardium

middle layer of involuntary striated muscle tissue

Which layer of the heart is responsible for physical contraction of heart muscle

myocardium

endocardium

innermost layer of the heart, lines chambers of the heart and forms surface of valves

role of endocardium

promotes flow of blood through heart and protects inner surfaces

tricuspid valve

separates right atrium from right ventricle

bicuspid (mitral) valve

Separates left atrium from left ventricle

pulmonary valve

lies between right ventricle and pulmonary arteries

aortic valve

lies between left ventricle and pulmonary aorta