Cardiology Jugular Venous Pulse

Cannon a Wave

The a wave of the jugular venous waveform occurs as a result of right atrial contraction. When there is resistance to right ventricular filling, right atrial contraction generates increased pressure, resulting in large a waves. Cannon a waves usually occur intermittently, unlike giant a waves, which occur with every beat. The cannon a wave occurs as a result of atrial contraction against a closed tricuspid valve, which occurs sporadically as a result of atrioventricular dissociation. When cannon a waves occur with every beat, it indicates atrioventricular dissociation with retrograde atrial activation from supraventricular tachycardia (e.g., junctional rhythm).
Card Tutorial

Patient 2

This is an older woman with complete heart block