Cannon A Waves of Complete Heart Block on Physical Exam A patient presented to clinic with lightheadedness and dyspnea. What is shown on the neck exam? What is the ddx? The a wave is the increase in CVP due to atrial contraction. This normally occurs during ventricular diastole, when the tricuspid valve (TV) is open. When the atrium contracts against a closed TV, this results in “cannon a waves”! This can occur in multiple conditions in which the atrium and ventricle are not coordinated – the ddx includes (1) complete heart block (2) VT (3) PAC/PVCs So why did our patient have cannon a waves? She had complete heart block. UCSF IM Chiefs @UCSFIMChiefs #CannonA #AWaves #Complete #HeartBlock #PhysicalExam #Clinical #Video #JVP
