EXPH 3200- EKG Rhythms

normal sinus rhythm

HR = 60-100 bpm

Rhythm is regular

sinus bradycardia

HR < 60 bpm

Rhythm is regular, but slow

sinus tachycardia

HR > 100 bpm

Rhythm is regular, but fast

sinus arrhythmia

Rhythm is slightly irregular with areas that are faster or slower

Healthiest of all sinus arrhythmias

sinus arrest/pause

Normal sinus rhythm with "dropped beats"

An entire PQRST is missing (period of asystole)

Scariest of all sinus arrhythmias

supraventricualr arrhythmias overview

Originate in atria = P wave

P waves often look abnormal or absent within a single lead

types of supraventricular arrhythmias

premature atrial contraction (isolate and couplet)

supraventricular tachycardia

atrial flutter

atrial fibrillation

premature atrial contraction (PAC)

Beat is early, P wave is absent or changes, QRS is normal

A slight pause follows the PAC (compensatory pause for absolute refractory)

isolated (1 PAC) or couplet (every other PAC)

supraventricular tachycardia

Multiple PACs in a row

Onset and termination are sudden and abrupt

HR = 150-250 bpm

atrial flutter

Atrium fires repetitively at a fast rate with some of the impulses blocked from ventricles

P and T wave can combine after QRS

Atrial rate = 250-350 bpm

P waves = classic "saw tooth pattern"

P:QRS = more P waves than QRS (3:1)

NOT IN NORMAL HEARTS

atrial fibrillation (a-fib)

Atria are so irritable that a multitude of foci initiate impulse causing atrium to "quiver"

Atrial rate = 350-600 bpm (chaos)

P:QRS = irregular

NOT IN NORMAL HEARTS

junctional rhythms overview

originate in the AV node

abnormal P waves (inverted) or no P waves are possible

premature junctional contraction (PJC)

Irritable focus produces an early beat

Usually followed by a pause

Similar to PAC

junctional escape beat

Higher pacemaker (SA node) site fails

AV node produces beat (no P wave) to protect against asystole

switch off between SA and AV node producing beat (P and no P)

junctional rhythm

Irritable foci speeds up to override the SA node for control (possible SA node failure)

P wave is lost completely

goes directly into QRS complex

atrial rate = ventricular rate

RATE = 40-60 bpm

accelerated junctional rhythm

same characteristics as junctional rhythm

RATE = > 60 bpm

ventricular arrhythmias overview

originate in the ventricles

ventricular rate = 20-40 bpm

abnormal/wide QRS complex

types of ventricular arrhythmias

premature ventricular contraction

ventricular escape beat

accelerated ventricular rhythm

ventricular tachycardia

ventricular fibrillation

asystole

premature ventricular contraction (PVC)

Irritable focus in the ventricles fires prematurely to produce a single ectopic beat

QRS findings are wide

couplet (every other) or trigeminy (every third)

ventricular escape rhythm

SA and AV node fail, so the ventricles produce an impulse to protect from asystole

RATE = 20-40 bpm

no P waves

QRS > 0.12 seconds (VERY wide)

NOT IN CLINICALLY NORMAL HEARTS

accelerated ventricular escape rhythm

same characteristics as ventricular escape rhythm

RATE = 40-100 bpm

ventricular tachycardia

A run of 3 or more consecutive PVCs

RATE = 100-300 bpm

wide QRS

ventricular fibrillation

Multiple foci within the ventricle become irritable and generate uncontrolled, chaotic impulses

quivering baseline

asystole

Heart has lost its electrical activity

EKG = flat line

AV conduction blocks overview

Inability of the AV junction to conduct every normal impulse generated above it to the ventricles within the normal amount of time

abnormal P waves and PR intervals

types of AV conduction blocks

1st degree AV block

2nd degree AV block (type I and type II)

3rd degree AV block

1st degree AV block

The AV node holds each sinus impulse longer than normal before allowing the conduction through the ventricles

PR interval = prolonged (> 0.20 seconds), but consistent

2nd degree AV block wenkebach

Not every atrial impulse is able to pass through the AV node into the ventricles

extra P wave, where there is no QRS

PR interval = progressively lengthening, until a P wave (atrial conduction) is blocked from entering the ventricles (not conducted)

ventricular rate < atrial rate

2nd degree AV block mobitz type II

blocked atrial contractions (extra P waves with no QRS)

PR interval = within normal limits/consistent until a P wave is not conducted (stranded P waves are seen); no progressive lengthening of PR interval

ventricular rate < atrial rate

NOT SEEN IN NORMAL HEARTS

3rd degree AV block

P and QRS are NOT communicating (atrial and ventricles function normally, but are completely dissociated)

AV node cannot conduct impulses, ventricles generate an escape rhythm (20-40 bpm)

PR interval = cannot determine (random P waves)

wolff-parkinson-white pattern (pre excitation)

PR interval is shortened < 0.12 seconds

P wave blends in with QRS (delta wave)

The QRS is widened secondary to early stimulation of the ventricles

long QT syndrome

Increased risk for sudden death (genetic predisposition)

QTc > 460 msec

right bundle branch block

widened QRS (>0.12s)

double/notched R waves (best to look in V1 and V2)

left bundle branch block

V1 and V2 have neg deflection with wide QRS

widened QRS

right ventricular hypertrophy

R wave progressively smaller from V1 to V4 (abnormal progression)

left ventricular hypertrophy

left axis deviation

high R waves in V5 and V6

right atrial enlargement

very tall P wave in right sided leads

left atrial enlargement

wide/biphasic P wave in left sided leads