Overview of sinoatrial exit block

First Degree SA Exit Block

Not detectable on ECG

Second Degree SA Exit Block: Type I

Progressively shortened PP intervals then a missed PQRS

Second Degree SA Exit Block: Type II

Constant PP interval with intermittent missed PQRS

Third Degree SA Exit Block

Complete lack of P waves and QRS complexes ± escape rhythm

Overview of atrioventricular block

First Degree AV Block

PR Interval >200ms

Second Degree AV Block: Type I Mobitz

Progressive PR prolongation then a missed QRS complex

Second Degree AV Block: Type II Mobitz

Constant PR interval with intermittent missed QRS complexes

Advanced Second Degree AV Block

Two or more missed QRS complexes

Complete AV Block

Complete dissociation of P waves and QRS complexes

Left Bundle Branch Block

Wide QRS, broad R / no Q in lateral leads

Left Anterior Fascicular Block

Left axis deviation, QRS 45ms in aVL

Left Posterior Fascicular Block

Right axis deviation, QRS <120ms, rS in I / aVL, qR in III and aVF

Right Bundle Branch Block

Wide QRS, RSR pattern, slurred S wave

Bifascicular Block

RBBB + left or right axis deviation

Trifascicular Block

Incomplete or complete