Pulsus paradoxus is defined as an inspiratory systolic fall in arterial pressure of

10mmHg. It not only occurs in cardiac tamponade, but also in massive PE, severe

COPD and hypotension/shock.

Cannon a waves occur when the atria and ventricles contract at the same time. The causes are complete AV block, ventricular tachycardia and AV nodal reentry tachycardia