Ventricular Arrhythmias

Question 1

Premature Ventricular Contractions

Answer 1

A focus in the ventricle generates and AP before the nex scheduled SA nodal AP. On ECG

1) Premature
2) Ectopic, thus QRS morphology will be different than AV nodal generated QRS.
3) Wide complexes, since they come from the ventricles they transmit from myocyte to myocyte.
4) Compensatory pause after PVC, the extra AP causes SA node to become refractory, causing it to skip a beat and will resume exactly 2 P to P intervals after last normal sinus beat.

Question 2

Ventricular Tachycardia

Answer 2

Wide QRS complex rhythm originating in the ventricles at rate > 100 bpm. Can be either monomorphic or polymorphic (eg Torsades de Pointes).