ECG Rhythm Interpretation

atrial pacemaker

Rhythm: Regular if 1:1 pacing Rate: Varies with underlying rhythm P wave: Paced beats similar in size and shape, pacing artifact before P wave PR Interval: varies P:QRS Ratio: normal if normal AV conduction QRS duration: <0.12 seconds

ventricular pacemaker

Rhythm: Regular if 1:1 pacing Rate: Varies with underlying rhythm P wave: may be present PR Interval: varies P:QRS Ratio: varies with underlying rhythm QRS duration: Paced beats will be similar in size and shape, pacing artifact before QRS

Premature Ventricular Contraction (PVC)

Rhythm: Underlying rhythm, except for PVC Rate: Underlying rhythm P wave: Absent or disassociated from ectopic beat PR Interval: absent P:QRS Ratio: underlying rhythm QRS duration: widened or bizarre

Sinus Block and Sinus Arrest

Rhythm: Usually regular, irregular during pause Rate: 60-100 P wave: Normal, absent during pause PR Interval: 0.12-0.20 seconds P:QRS Ratio: 1:1 QRS duration: <0.12 seconds QT Interval: Normal, unmeasurable during pause

Asystole

Rhythm: absent Rate: 0 P wave: None PR Interval: None P:QRS Ratio: None QRS duration: None QT Interval: None

Ventricular Fibrillation

Rhythm: chaotic Rate: 0 P wave: None PR Interval: None P:QRS Ratio: None QRS duration: None OT Interval: None

Ventricular Tachycardia: Torsades de Pointes

Rhythm: irregular and chaotic Rate: Ventricular 250-350 P wave: obscured PR Interval: absent P:QRS Ratio: N/A QRS duration: >0.12

Junctional Tachycardia

Rhythm: regular Rate: 100-160 P wave: Inverted in Lead II or hidden, can be before or after the QRS PR Interval: short or not measurable P:QRS Ratio: 1:1, if P wave is visible QRS duration: <0.12 seconds

sinus tachycardia

Rhythm: regular Rate: 101-160 P wave: Normal PR Interval: 0.12 - 0.20 seconds P:QRS Ratio: 1:1 QRS duration: <0.12 seconds QT Interval: May be shortened

Junctional Rhythm

Rhythm: regular Rate: 40-60 P wave: Inverted in Lead II or hidden, can be before or after the QRS PR Interval: short or not measurable P:QRS Ratio: 1:1, if P wave is visible QRS duration: <0.12 seconds

Accelerated Junctional Rhythm

Rhythm: regular Rate: 60-100 P wave: Inverted in Lead II or hidden, can be before or after the QRS PR Interval: short or not measurable P:QRS Ratio: 1:1, if P wave is visible QRS duration: <0.12 seconds

normal sinus rhythm (NSR)

Rhythm: regular Rate: 60-100 P wave: PR Interval: 0.12-0.20 seconds P:QRS Ratio: 1:1 QRS duration: <0.12 seconds QT Interval: 0.32-0.44

Sinus Bradycardia

Rhythm: regular Rate: <60 P wave: normal PR Interval: 0.12-0.20 seconds P:QRS Ratio: 1:1 QRS duration: <0.12 seconds QT Interval: may be prolonged

ventricular tachycardia

Rhythm: regular Rate: >100 P wave: obscured PR Interval: absent P:QRS Ratio: N/A QRS duration: >0.12 seconds

Atrial Tachycardia/ Supraventricular Tachycardia (SVT)

Rhythm: regular Rate: >160 P wave: may be hidden PR Interval: unable to measure P:QRS Ratio: 1:1 QRS duration: <0.12 seconds

1st degree heart block

Rhythm: regular Rate: Underlying rhythm P wave: normal PR Interval: >0.20 seconds P:QRS Ratio: 1:1 QRS duration: <0.12 seconds

Atrial Flutter

Rhythm: regular or irregular Rate: Atrial 250-400 Ventricular varies P wave: flutter waves, sawtooth PR Interval: not measured P:QRS Ratio: Variable-3:1, 4:1 QRS duration: <0.12 seconds

Premature Atrial Contraction (PAC)

Rhythm: regular, except PAC Rate: depends on underlying rhythm P wave: Premature P wave different from other P waves, may be normal depending on location PR Interval: 0.12-0.20 seconds, PAC interval may be different P:QRS Ratio: 1:1 QRS duration: <0.12 seconds

2nd degree heart block (Type I) (Wenkebach)

Rhythm: Atrial Regular; Ventricular Irregular Rate: underlying rhythm P wave: normal PR Interval: progressively lengthens P:QRS Ratio: variable, more P's than QRS's QRS duration: <0.12 seconds

3rd degree heart block

Rhythm: Atrial regular; Ventricular regular Rate: Atrial 60-100; Ventricular 20-60 P wave: normal, may be hidden PR Interval: varies, no relationship between P's and QRS's P:QRS Ratio: varies QRS duration: normal or wide, depending on level of the block

2nd degree heart block (Type 2)

Rhythm: Atrial regular; Ventricular regular/ irregular Rate: underlying rhythm P wave: normal PR Interval: constant, may be normal or prolonged P:QRS Ratio: variable, more P's than QRS's QRS duration: normal if block is at bundle of His, wide if block is at bundle branches

Sinus Arrhythmia

Rhythm: Irregular Rate: 60-100 P wave: normal PR Interval: 0.12-0.20 seconds P:QRS Ratio: 1:1 QRS duration: <0.12 seconds QT Interval: may vary slightly

atrial fibrillation

Rhythm: Irregular Rate: Atrial >400 Ventricular Varies P wave: fibrillatory waves PR Interval: not measurable P:QRS Ratio: not measurable QRS duration: <0.12 seconds

AV sequential pacemaker

Rhythm: Regular if 1:1 pacing Rate: Varies with underlying rhythm P wave: P waves should follow atrial pacing spike PR Interval: varies P:QRS Ratio: Should be 1:1 for paced beats QRS duration: QRS complex should follow ventricular pacing spike