Ventricular escape rhythm
A protective backup rhythm arising from a focus in the ventricular myocardium when every faster pacemaker has failed.
Key ECG features
- ✓Wide, bizarre QRS complexes
- ✓Slow rate
- ✓Beats arrive late, after a pause
- •Regular rhythm
- •No consistent preceding P wave
✓ required · • typical
ECG characteristics
Wide, bizarre QRS complexes resembling a ventricular premature complex, but arriving late rather than early, at the slow rate the ventricles set for themselves, with no consistent preceding P wave. The rhythm is regular.
This illustration is schematic. Dashed line is a normal rhythm. The grid is not drawn to scale.
Common causes
Sinus arrest, high-grade or complete AV block, or profound bradycardia - that is, failure of both the sinus node and the junction to pace.
Why it matters
Escape beats must never be suppressed: they are the heart's last line of defense. The clinical problem lies with the failed sinus node or conduction system, not with the escape focus itself.
Differentiate from
- Ventricular premature complexesIdentical in shape. Escape beats arrive late, after a pause; premature complexes arrive early. Escape beats must never be suppressed.
- Accelerated idioventricular rhythmThe same focus firing faster, competing with a sinus node that is still working, rather than rescuing one that has failed.
- Junctional escape rhythmBoth are rescue rhythms. Junctional escape is narrow and a little faster because it starts above the ventricles.
- Third-degree (complete) AV blockComplete AV block is the commonest reason a ventricular escape rhythm appears - look for dissociated P waves above it.
- Ventricular tachycardiaEqually wide and equally ventricular, but fast and early rather than slow and late.