capture beat

In the presence of complete heart block, fusion or capture beats will never be seen.

Fusion beat and capture beat.

In some cases of ventricular tachycardia (VT) with atrioventricular dissociation, the sinoatrial node may transiently "capture" the ventricles, producing a capture beat, which has a normal QRS complex duration, or a fusion beat, in which the sinus and ventricular beats coincide to produce a hybrid complex beat.