ECG readings

normal sinus rhythm

Originate: SA node

QRS complex: narrow

P wave: before QRS, same

Heart rate: 60-100 bpm

R-R intervals: regular

sinus bradycardia

Originate: SA node

QRS complex: narrow/wide

P wave: before QRS, same

Heart rate: <60 bpm

R-R intervals: regular

sinus tachycardia

Originate: SA node

QRS complex: narrow

P wave: before QRS, same

Heart rate: >100 bpm

R-R intervals: regular

sinus arrhythmia

Originate: SA node

QRS complex: narrow

P wave: same

Heart rate: 60-100 bpm

R-R intervals: irregular

wandering atrial pacemaker

Originate: AV node

QRS complex: narrow

P wave: at least 3 different waves

Heart rate: <100 bpm

R-R intervals: regular

AV nodal junctional rhythm

Originate: AV node

QRS complex: narrow

P wave:

-Top of AV node = inverted, prior to QRS

-Middle of AV node = hidden in QRS

-Bottom of AV node = inverted, after QRS

Heart rate: 40-60 bpm

R-R intervals: regular

-Accelerated junctional rhythm: >60-100 bpm

-Junctional tachycardia: >100 bpm

multifocal atrial tachycardia

Originate: multiple rapidly firing atrial impulses

QRS complex: narrow

P wave: different

Heart rate: >100 bpm

R-R intervals: irregularly irregular

atrial flutter

Originate: atrial automaticity focus in self-perpetuating loop

QRS complex: narrow

P wave: saw tooth pattern

Heart rate: 250-400 bpm

R-R intervals: regular

atrial fibrillation

Originate: atrial is fibrillating and not contributing to ventricular filling

QRS complex: narrow

P wave: none

Heart rate: variable

R-R intervals: irregular

Unsynchronized and chaotic

supraventricular tachycardia (SVT)

Originate: atrial or AV nodal focus

QRS complex: narrow

P wave: may not be identifiable

Heart rate: 140-280 bpm

R-R intervals: regular

paroxysmal SVT

Abrupt onset

Abrupt offset

monomorphic ventricular tachycardia

Originate: ventricular automaticity focus

QRS complex: wide

P wave: none

Heart rate: very rapid

R-R intervals: regular

torsades de pointes

Originate: ventricular automaticity focus

QRS complex: twist

P wave: none

Heart rate: very rapid

R-R intervals: irregular

ventricular fibrillation

Originate: multiple weak ectopic ventricular foci

QRS complex: none

P wave: none

Heart rate: none

R-R intervals: irregular

Ventricle quivers

No cardiac output, no perfusion, no pulse

premature atrial contraction (PAC)

Originate: ectopic atrial focus fires impulse within SR

QRS complex: narrow

P wave: different

Heart rate: 60-100 bpm until PAC

R-R intervals: regular until premature beat causes interval to come earlier than expected

Pause after premature beat

premature junctional contraction (PJC)

Originate: AV node

QRS complex: narrow

P wave:

-None

-inverted before

-inverted after

Heart rate: 60-100 bpm until PJC

R-R intervals: regular until PJC

premature ventricular contraction (PVC)

Originate: irritable ventricular focus

QRS complex: wide

P wave: same until PVC

Heart rate: 60-100 bpm until PVC

R-R intervals: regular until PVC

Regularity:

-Isolated

-Bigeminy (every other beat)

-Trigeminy (every 3rd beat)

Series:

-Couplet (2 in row)

-Triplet (3 in row)

Morphology:

-Unifocal (same morphology)

-Multifocal (different morphology)

junctional escape beat

Regular sinus rhythm with a long pause followed by a singular junctional beat and return to normal sinus

ventricular escape beat

Sinus rhythm → long pause → singular ventricular beat → return to normal rhythm

atrial escape rhythm

Failure of the sinus node → brief pause → takeover of rhythm by another atrial impulse

-P wave will differ following pause

junctional escape rhythm

Failure of the sinus node → brief pause → takeover of rhythm by the AV node

-inversion or absence of P wave will present in new rhythm

ventricular escape rhythm

Failure of the sinus node → brief pause → takeover of rhythm by focus in the ventricle

asystole

Failure of the sinus node → no assumption of pacemaker activity by other areas → no cardiac output, no perfusion, and no pulse

first degree AV block

Delayed impulse from SA to AV node → prolonged PR interval with each beat

-1 box large

-rest will look normal

second degree type I AV block (wenckebach)

Impulses through the AV node take progressively longer showing then are completely blocked

-PR interval will slowly become more prolonged → P wave with no present QRS complex to follow → rhythm picks back up

second degree type II AV block

Atrial impulses are locked sporadically

-NO prolongation prior to dropping of the QRS complex → PR interval will be constant

third degree

Sinus beats are independent from the beat originating in the AV node or ventricle

-There will be zero relation of P waves to the QRS complex

left bundle branch block

QRS = >0.12 seconds

Primarily V1 but also V2-V3

-Deep S waves

V5-V6

-Tall R waves

right bundle branch block

QRS = >0.12 seconds

Primarily V1 but also V2-V3

-RSR appearance (M wave)

V5-V6

-Wide, slurred s wave

right ventricular hypertrophy

V1 = Dominant R wave

-Larger than S wave or > 7 mm tall

-May also see T wave inversions

V5&6 = Dominant S wave

-Larger than R wave or > 7 mm tall

left ventricular hypertrophy

I, aVL = Increased amplitude of R waves

III, aVR, V1-V3 = Increased depth of S waves

V5-V6 = Tall R waves

-Will also see ST & T wave abnormalities consistent w/ LV strain

inferior myocardial infarction

ST elevations in leads II, III, aVF

lateral myocardial infarction

ST elevations in leads I, aVL, V5, V6

anterior myocardial infarction

ST elevation in leads V3 and V4

inferior + posterior myocardial infarction

ST elevation in leads II, III, aVF + ST depression in leads V1-V3

myocardial ischemia

ST depression consistent across leads with no presence of elevation

moderate hypokalemia

prominent U wave

severe hypokalemia

hyperkalemia

hypothermia

Osborne J-wave

-occurs near J-point on the S wave and ST junction