[N109] Electrocardiography

Atrial / Ventricular / Ventricular

The P wave represents ________ depolarization, while the QRS complex represents ________ depolarization, and the T wave represents ________ repolarization.

Sino-atrial (SA) node

It is the heart’s physiologic or dominant pacemaker; center of automaticity and discharges an impulse between 60 and 100 times per minute

c) 60–100 bpm

The SA node is the physiologic pacemaker of the heart. What is its normal firing rate?
a) 20–40 bpm
b) 40–60 bpm
c) 60–100 bpm
d) 100–120 bpm

AV junction (40–60 bpm)

You see a rhythm strip with absent P waves and narrow QRS complexes at 45 bpm. Which pacemaker is likely in control?

• AV junction (AV node and bundle of His) (40-60 bpm)

• Ventricles (20-40 bpm)

• Atria (80 bpm)

What are the potential pacemakers of the heart if SA node fails and their respective impulse?

False (they only record activity, no electricity delivered)

True/False:
ECG leads transmit small electrical currents into the patient’s body to stimulate the heart.

BONUS: Conduction system of the heart

The ECG's P-wave, QRS complex, and T-wave correspond to atrial depolarization (contraction), ventricular depolarization (contraction), and ventricular repolarization (relaxation), respectively.

Enumerate the sequence in the cardiac cycle and how each mechanical event corresponds to an ECG.

Lead

This provides a view of the heart’s electrical activity between one positive pole and one negative pole.

Electrodes; waveforms

_______________ placed on the skin measures the direction of electrical currents discharged by the heart. These currents are then transformed into _____________.

Deflection

This pertains to a wave or deflection seen on an electrocardiogram (ECG) that represents the electrical activity of the heart, specifically the movement of a depolarization or repolarization wavefront

When a wave of electrical activity moves towards a positive electrode on the ECG, it causes an upward (positive) deflection;

whereas movement away from it causes a downward (negative) deflection.

What is the main difference between the positive and negative electrodes in terms of deflection?

A bipolar lead system means that each displayed ECG lead has a positive and a negative pole. (one lead acts as a ground)

Explain the bipolar lead system in ECG.

FALSE: Leads do not transmit any electricity to the patient; they record electrical impulses.

True/False:

Leads have electricity that is transmitted to the patient which helps record the electrical impulses.

Plane

This refers to the cross-sectional prospective of the heart’s electrical activity.

Frontal plane (picture ng puso mula sa harap)

Vertical cut through the middle of the heart, shows anterior to posterior view.

Horizontal plane (picture ng puso mula sa taas)

transverse cut through the middle of the heart, shows either superior or inferior view.

3-lead ECG placement

5-lead ECG placement

12-Lead ECG placement

Diluted plain alcohol with PNSS

• cotton

• wet the electrodes before placing them onto the patient

What is the specific solution used for the conduction system?

Place the lead nearest to the stump

Paano if phantom limb?

18-lead ECG

This lead ECG is usually used in pediatric patients due to anatomic differences

Dextrocardia (12-lead ECG is used)

This is a rare condition where the heart is positioned on the right side of the chest instead of the left.

Einthoven’s triangle

This is a theoretical triangle formed by placing electrodes on the right arm (RA), left arm (LA), and left leg (LL). These three points correspond to the locations of the limb leads in a standard ECG (leads I, II, and III).

• identify indication (brief NHH)

• Patient should be well-rested

• Patient should avoid activities/food that affect heart activity (coffee, running, alcohol, etc.)

• Minimize anxiety by saying to the patient na walang electricity na dadaloy sa patient

• Remove metals in the patient’s body (generally no effect, but to secure no interruption in electric readings)

Enumerate at least two nursing considerations prior to performing ECG

• Relaxed, extended extremities (dapat hindi nakadikit sa wall or sa railings), expose the area only, hindi nakadikit yung foot sa foot ng bed.

• Diluted 75% alcohol and sterile water in cotton balls

  • Acts as liquid conductor and makes is more easier to place the suctions

Nursing responsibilities during ECG

No, unless ordered by the physician in special circumstances

Do you need to hold medications prior to ECG?

The lead is placed on the nearest left lower limb or on top of the slump

Where should the left lower lead be placed in patients with above the knee amputation?

BONUS: 12-lead placement

b) It follows the heart’s natural conduction pathway

Lead II is considered the most important monitoring lead because:
a) It best reflects lateral LV wall
b) It follows the heart’s natural conduction pathway
c) It shows anterior wall activity
d) It is least prone to artifact

ground

In Einthoven’s Triangle, the right leg electrode acts as a _________.

b) V1, V2 → V4 → V5, V6 → V3

Correct order for placing chest leads in a 12-lead ECG is:
a) V1–V6 in numeric order
b) V1, V2 → V4 → V5, V6 → V3
c) V1, V2 → V3 → V4 → V5, V6

0.04 sec / 0.20 sec

On ECG paper, 1 small box horizontally = ______ sec; 1 large box = ______ sec.

c) Bundle branch block or ventricular rhythm

A QRS duration of 0.14 sec (normal: 0.06-0.10 sec) indicates:
a) Normal ventricular conduction
b) Narrow complex supraventricular rhythm
c) Bundle branch block or ventricular rhythm
d) Artifact

AV block

A PR interval of more than 0.20 seconds indicate?

Wolff–Parkinson–White syndrome (pre-excitation)

A PR interval of less than 0.12 seconds indicates?

Ischemia or MI (ST segment should normally be flat)

What should you suspect if there is an elevation/depression of the ST segment?

Hyperkalemia

Peaked T wave may indicate?

Ischemia

Inverted T wave may indicate?

When the patient is in haloperidol with the risk for Torsades de Pointes

When should we strictly monitor the QT interval?

Normal: <0.44 sec (men), <0.46 sec (women)

What are the normal values of QT interval for men and women?

True

(True/False):
ST elevation in ≥2 contiguous leads is diagnostic for myocardial infarction.

Hypomagnesemia → Narrow PR interval (wrong; it prolongs QT → Torsades)

Which electrolyte imbalance matches the wrong ECG finding?

• Hyperkalemia → Peaked T waves

• Hypokalemia → Flattened T waves / U waves

• Hypercalcemia → Short QT

• Hypomagnesemia → Narrow PR interval

BONUS: ECG notes

1. P Wave (is there a P wave?)

2. Rhythm (Is the rhythm regular?)

3. Heart rate (compute)

4. PR Interval (is it constant? does it vary?)

5. QRS Complex (is it narrow <0.12 sec; or wide >0.12 sec?)

6. QT Interval (prolonged or normal?)

7. ST Segment (elevated, depressed, or isoelectric?)

8. T Wave (upright, peaked, or inverted?)

What are the steps in ECG interpretation? (RRPPRQRSSTQT)

0.12–0.20 / 0.06–0.10 / 0.44

Normal PR interval: ______ sec. Normal QRS: ______ sec. Normal QT: ≤______ sec.

Second-degree AV block, Mobitz I (Wenckebach)

You see progressive PR prolongation until a QRS is dropped. This is most consistent with:

b) Sinus bradycardia

A 25-year-old athlete has HR 45 bpm, regular rhythm, upright P waves before every QRS. Diagnosis?
a) Sinus tachycardia
b) Sinus bradycardia
c) Junctional escape rhythm
d) 1st-degree AV block

Ventricular fibrillation

Which rhythm is always pulseless?

• Ventricular fibrillation

• Pulseless VTach

• Asystole

• Supraventricular tachycardia

Sawtooth / Irregular chaotic

Atrial flutter shows ______ wave pattern, while atrial fibrillation shows ______ baseline.

Supraventricular Tachycardia (SVT)

Your patient’s ECG shows a rapid, narrow-complex tachycardia at 180 bpm, no visible P waves. What’s the most likely diagnosis?

b) Atrial fibrillation

Which arrhythmia carries the highest risk of stroke due to embolism?
a) Atrial flutter
b) Atrial fibrillation
c) Sinus bradycardia
d) PVCs

• Narrow QRS

Which is not a PVC characteristic?

• Wide QRS

• Absent P waves

• Narrow QRS

• Can appear as bigeminy/trigeminy

b) V-tach

A run of ≥6 PVCs per minute may progress to:
a) Asystole
b) V-tach
c) Atrial flutter
d) Junctional tachycardia

QT / Magnesium

Torsades de Pointes is a polymorphic ventricular tachycardia usually caused by prolonged ______ interval, often due to low ______.

False (always pulseless)

(True/False):
Ventricular fibrillation can sometimes have a pulse.

a) 1st degree

Which AV block is described as “PR interval >0.20 sec, but every P followed by QRS”?
a) 1st degree
b) 2nd degree Mobitz I
c) 2nd degree Mobitz II
d) 3rd degree

Mobitz I (Wenckebach)

“PR progressively lengthens, then a QRS drops” = ______ AV block.

2nd degree AV block, Mobitz II

Your patient has constant PR intervals, but some P waves are not followed by QRS. Diagnosis?

• 3rd degree

Which block has no relationship between P waves and QRS complexes?

• 1st degree

• Mobitz I

• Mobitz II

• 3rd degree

c (Tall peaked P = right atrial enlargement)

Which of the following is NOT a sign of left atrial enlargement?
a) Notched P wave in lead II
b) Wide, biphasic P wave in V1 (terminal negative deflection)
c) Tall peaked P wave in lead II
d) P wave duration > 0.12 s

True

True/False: ST depression can represent myocardial ischemia OR reciprocal changes of an MI.

Anterior MI / Lateral MI / Inferior MI

• ST elevation in V1-V4 → _______

• ST elevation in V5-V6, I, aVL → _______

• ST elevation in II, III, aVF → _______

b) Atrial fibrillation

Which rhythm is “irregularly irregular” with no P waves?

a) Atrial flutter
b) Atrial fibrillation
c) SVT
d) Junctional rhythm

c) Hypothyroidism

Which is NOT a cause of sinus tachycardia?
a) Fever
b) Anxiety
c) Hypothyroidism
d) Pain

Ventricular tachycardia

Wide QRS (>0.12 s), tachycardia, no P waves → ___________.

True

True/False: V-fib is shockable, but asystole is not.

a) atrial fibrillation

“Holiday Heart Syndrome” arrhythmia after binge drinking?
a) Atrial fibrillation
b) VT
c) Junctional rhythm
d) WPW

c (asystole → CPR + epi, NOT defibrillation)

Odd-one-out: Which rhythm requires IMMEDIATE defibrillation?
a) Ventricular tachycardia (pulseless)
b) Ventricular fibrillation
c) Asystole
d) Torsades de pointes (pulseless)

• 1st step: P wave present

  • Each P wave has QRS complex

• 2nd step: Regular 

• 3rd step: 75 HR

  • 1500 / 21 = 71.429 or 72 bpm

• 4th step: 0.12 seconds (normal)

  • PR interval

  • 4 x 0.4 = 0.16

• 5th step: 0.04 seconds

  • QRS duration

  • 1 x 0.04 = 0.04

• 6th: 0.4 seconds

  • QT interval

  • 9 x 0.04 = 0.36

• 7th: slightly depressed

• INTERPRETATION: Normal sinus rhythm with a heart rate of 75 BPM, slightly slightly depressed ST segment, and upright T-wave

Interpret the ECG strip:

Sinus bradycardia

• A slower-than-normal heart rate, usually <60 bpm, but rhythm remains regular

• SLOW RATES (From Registered RN)

  • Sick Sinus Syndrome (SA Node damaged)

  • Low Thyroid Hormone

  • Older Adult

  • Weak/Damaged Heart Muscle

  • Raised ICP (Part of Cushing’s Triad)

  • Athlete

  • Toxicity (beta-blockers, calcium channel blockers, clonidine, digoxin)

  • Electrolyte imbalance (hyperkalemia)

  • Stimulation of vagal response

• Causes

  • Can occur naturally in athletes, during sleep, or due to increased vagal tone. 

  • Also caused by medications (beta-blockers, calcium channel blockers)

  • Hypothyroidism

  • Hypothermia 

• Associated Conditions: Often benign but may lead to dizziness or fatigue if too slow. Common in well-conditioned individuals, but can indicate issues in older adults.

• Treatment

  • If asymptomatic:

    • Does not have any treatment

    • Assess signs and symptoms

  • If symptomatic 

    • Medications (ADE)

      • Atropine

      • Dopamine

      • Epinephrine

    • Temporary pacemaker

Determine the sinus node arrhythmia:

slower-than-normal heart rate, usually <60 bpm, but rhythm remains regular

• A faster-than-normal heart rate, usually >100 bpm, with regular rhythm.

• Causes

  • Often due to exercise, stress, fever, pain, dehydration, anemia, or stimulants like caffeine. 

  • Also seen in hyperthyroidism and heart failure.

  • From Registered RN (TACHY HEARTS)

    • Temperature elevation

    • Aerobic exercise

    • Cardiac disease

    • Hyperthyroidism

    • Yelp

    • Hemorrhage (Hypovolemic Shock)

Associated Conditions: Usually a normal response to stress or exercise, but chronic tachycardia can indicate a compensatory mechanism for conditions like heart failure or hypovolemia.

Determine the sinus node arrhythmia:

A faster-than-normal heart rate, usually >100 bpm, with regular rhythm.

Sinus arrhythmia

Determine the sinus node arrhythmia:

abnormal rhythm and irregular

Sinus arrest/block

Determine the sinus node arrhythmia:

Sinus node stops resulting in a missing beat. Rhythm is irregular

• Normal sinus rhythm with occasional premature atrial complex

Premature atrial complex

• Premature = occurred earlier than usual

  • May P wave 

  • Comes from atrial origin kaya premature atrial complex

  • Ventricular complex = walang P wave, QRS is wide

• Problems lies within the T wave

• Normal sinus rhythm with occasional premature atrial complex

• Isearch → PQRST cardiac cycle

• Interpretation: Normal sinus rhythm with heart rate of _ with occasional atrial premature complex

Determine the atrial dysrhythmia

Wandering atrial pacemaker

• P waves ay different yung presentation every PQRST which makes it wandering

• WAP (60 to 100/100)or MAT (>100/100)- difference is the rate 

• Does not happen usually sa mga pasiyente (at most 2 pa lang na-eencounter ni sir)

• Mosty atrial tachycardias are irregular in nature

• Atrial contractions ay paiba-iba, irregular

• Less than 60 bpm

• 60-100 kasi kapag more than 100 = multifocal atrial tachycardia

Determine the atrial dysrhythmia:

Different presentation of P waves every PQRST

Multifocal atrial tachycardia

• P waves ay iba iba ang shape and more than 100 rate

• More than 100 bpm

• Multifocal kasi iba-iba ang focus ng atria kasi wandering

• Irregular

• Tapos more than 100 bpm

• 6-second strip ang pang-measure kasi irreg

Determine the atrial dysrhythmia:

Different P wave shapes with more than 100 bpm rate, irregular

Atrial Tachycardia

• 120-250 bpm

• Regular unless may variable

• Compared to WAP and MAT, ito ay tachy arrhythmias that are 120-250 bpm pero regular rhythm

Determine the atrial dysrhythmia:

Atrial rate is 120-250 bpm, regular unless there is a variable block at the AV node; P waves with different shapes, precedes each QRS complex but may be hidden in preceding T wave.

Atrial Flutter

• Usually regular in nature compared to atrial fibrillation which has small S waves and is irregular 

• Big letter F wave, saw like patterns

• Defined and regular 

• 4:1 / 3:1 - P to QRS 

• Mataas atrial rate - F waves ang counting

• Galing ang problem sa atrium (big F waves)

• Saw tooth pattern

• There is a ratio of P to QRS (2:1 dapat)

  • Pero this is 4:1 or 3:1

  • Mas konti atrial rate compared sa A-Fib

Determine the atrial dysrhythmia:

Usually regular in nature compared to atrial fibrillation which has small S waves and is irregular; with big letter F waves that are in saw-like patterns; atrial rate varies between 250-350 bpm, most commonly 300.

Atrial Fibrillation

• Small and erratic / irregular rhythm: F waves (Fibrillation)

• 400 to 600 p waves

  •  Dahil irreg, ang ventricular rate ay normal lang

  • Pero ang atrial rate ay umaabot ng 40-60 x 10 = 400-600

• Common in the area, not effective yung pagpupuno ng heart chambers

• Irregular compared sa Aflutter

• At risk:

  • Embolic stroke

    • Hindi maganda ang pagkaka-pump ng blood kaya there is possibility of embolism

• We give: 

  • Blood thinners

  • Digoxin (anti-arrhythmia)

• Pulse is reflection of ventricular heart rate

• Mahalaga malaman ang ventricular rate ni px lalo na if naka-Digoxin siya

  • Kapag 50 bpm na lang ang ventricular rate ni px, huwag ibibigay muna ang Digoxin → dec HR (dahil anti-arrhythmia nga) = REFER to adjust dose

    • We don’t stop abruptly

    • Wean off din

Determine the atrial dysrhythmia:

Atrial rate is 400-600 bpm or faster, irregular, with the marked irregularity of the ventricular response. P waves not present while atrial activity is chaotic with no formed atrial impulses visible. Small and erratic with F waves that vary in size from coarse to very fine.

Atrial fibrillation with slow ventricular response

This type of atrial fibrillation has:

• Slow ventricular response → brady → systole → cardiac arrest

• Below 60 QRS

Atrial fibrillation with controlled ventricular response

This type of atrial fibrillation has 60-100 QRS

Atrial fibrillation with rapid ventricular response

This type of atrial fibrillation has:

> 100 QRS

Supraventricular tachycardia

Identify the Above A-V Arrhythmia:

• above 150s-170s HR

• burrowed P waves (no atrial depolarization)

• narrow QRS complex

Premature junctional rhythm

*Inverted P wave

Determine the Junctional dysrhythmia:

• rate: 60-100 bpm

• rhythm is regular except for occurrence of premature beats

• P waves are usually inverted; may occur before, during, or after the QRS complex of the premature beat

Premature ventricular contractions

• Prematurely  occurring

• QRS complex wide

• No P-waves

• Unlike PAC and PJC, may P waves kasi both galing sa atrial origin

• Ito ay VENTRICULAR origin

  • Kaya ventricular contraction ang problem

• Commonly seen sa patients because sa QRS

• From the ventricles, QRS complexes are wide → more than 0.1

• Walang P-wave

• They have wide QRS complexes

Determine the ventricular dysrhythmia:

• Rate is 60-100 bpm

• Rhythm is irregular due to the early beats

• QRS complex is wide and “bizarre” or “weird”; > 0.10 second in duration, varying in morphology (size, shape)

• Every second → Bigeminy

• Every third → Trigeminy

• Every fourth → quadrigeminy

• Dumadami ang PVC – occasional

• Identical (magkamukha) → Unifocal

• Different appearance (magkaiba ang itsura; inverted, upright) → Multifocal

• two → Couplet

• three → Triplet

• four → Quadruplet

• more than four → Runs of PVCs

Naming of PVCs:

• Every second →

• Every third →

• Every fourth →

• Dumadami ang PVC →

• Identical (magkamukha) →

• Different appearance (magkaiba ang itsura; inverted, upright) →

• two →

• three →

• four →

• more than four →

• Run the code already, 6 max lang PVCs in 1 minute.

  • E-cart, code for ACLS → clinical forethought, plan, recommend.

  • It may lead to Vtach

What should the team do if there are runs of PVCs or with more than 6 PVCs per minute?

Ventricular tachycardia

• VTACHS

• First thing to do is to check for pulse (pwedeng may pulse, pwedeng wala)

  • Pulse rate!!!

• Can be

  • Monomorphic

    • Iisa yung shape

  • Polymorphic

    • Iba-ibang shape

    • Most common: Torsades de Pointes

• Can be

  • Pulseless

    • (unlike V-Fib, laging pulseless)

  • With pulse

Determine the ventricular dysrhythmia:

• Ventricular rate is faster than 100 bpm

• can be monomorphic or polymorphic

• can be pulseless or with pulse

Torsades de Pointes

• QT interval is lengthening → VTachs sa pic sa baba (hypomagnesemia)

• Name based on morphology

  • Same and uniform shape - monomorphic

  • Polymorphic VTachs - Sample torsades de pointes (TDP), malalaking QRS complexes

  • Interventions: MgSO4, magnesium sulfate

TDP patients often have hypomagnesemia

Determine the ventricular dysrhythmia:

• potentially fatal type of polymorphic ventricular tachycardia (a rapid, irregular heart rhythm)

• QT internal is lengthening

  • QRS complexes appear to twist around the ECG baseline, a sign of a prolonged QT interval

Magnesium sulfate (they often have hypomagnesemia)

What should you prepare for patients with torsades de pointes?

Ventricular fibrillation

• Puro QRS complexes 

• ALWAYS PULSELESS

  • Unlike vtach which can either be pulseless or with pulse

  • Fine

  • Coarse - higher 

• V-Fib may appear like V-Tach minsan pero sa V-Tach may monomorphic pattern

  • V-Fib paiba-iba ang shapes

• V-Fib → no pulse → cardiac arrest

  • Do cardiac arrest algorithm

• Pulseless electrical activity (PEA)

  • normal sinus rhtyhm, no pulse

  • Run cardiac arrest algorthim

  • Mostly in patients na may hypovolemia, sepsis

    • Give fast drip PNSS to elevate the blood volume

Determine the ventricular dysrhythmia:

• Rate is rapid, uncoordinated, and ineffective

• Rhythm is chaotic and irregular

• P waves: none

• Always pulseless

Ventricular Asystole

• Assess the patient first

• Check the leads first

• Baka na-disconnect lang naman

• HUWAG KA MAG CARDIAC THUMP AGAD BHIE

Determine the ventricular dysrhythmia:

• Flatline

• No rate, rhythm, PR interval, QRS complex

First degree AV block

• Kaya mahaba ang PR interval - atrial ventricular depolarization.

• 7 x 0.4 = 0.28 (mas mataas sa 0.2 secs so prolonged)

  • Mukhang normal pero mas mahaba pala

• May delay sa AV conduction, may “block”

• Mgt: Transcutaneous pacing

Determine the A-V dysrhythmia (blocks):

• Prolonged PR interval (above 0.20 second)

• Rate can occur at any sinus rate, usually 60-100 bpm

• P waves are normal, precede every QRS

Second degree AV block: Mobitz Type 1 or Wenckebach

• Both type 1 and 2 have drops. 

• Increasing prolonged PR interval → Then drop

  • Gradual increase / prolong tapos biglang drop

• Mgt: Transcutaneous pacing

Determine the A-V dysrhythmia (blocks):

• Increasing prolonged PR interval → Then drop

• Rhythm is irregular, overall appearance of the rhythm demonstrates “group beating”

• P waves are normal, some P waves are not conducted to the ventricles, but only one at a time fails to conduct to the ventricle

• PR interval gradually lengthens in consecutive beats. The PR interval preceding the pause is longer than that following the pause

Second degree AV block: Mobitz Type 2

• Prolonged-same-prolonged-same- drop of QRS (PR interval length

• Mgt: OR agad kasi need ng transvenous pacing

• Mas masakit daw Type 2

  • Consistent tapos bigla kang iiwan (jan naman kayo magaling)

  • Type 1 may buildup so medyo sanay ka na, pawala na bago ma-drop

Determine the A-V dysrhythmia (blocks):

• Prolonged-same-prolonged-same- drop of QRS (PR interval length

• Rate can occur at any basic rate

• Rhythm is irregular due to blocked beats

• P waves are usually regular and precede each QRS

• PR interval is constant before conducted beats. The PR interval preceding the pause is the same as that following the pause

• QRS complex is usually wide due to associated bundle branch block

Third degree AV block

• Wala ng relationship yung drops and the PR interval 

• Mgt: Transvenous pacing

Determine the A-V dysrhythmia (blocks):

• Atrial rate usually normal; ventricular rate is <45 bpm

• rhythm is regular

• P waves are normal but dissociated from QRS complexes