Syncope caused by cough-induced complete atrioventricular block.

Cough syncope is a well-recognized syndrome in which loss of consciousness follows a bout of prolonged coughing. The pathophysiology of this syndrome has been attributed to lowered cerebral perfusion pressure consequent on an increased intrathoracic pressure, which lowers cardiac output (by a Valsalva mechanism) and impairs cerebral venous return. We report a case of cough-induced syncope in which ECG monitoring showed that coughing produced paroxysmal atrioventricular block with ventricular asystole. Such a case has not previously been documented.