Cough syncope presenting as Mobitz type II atrioventricular block--an electrophysiologic correlation.

A 34-year-old man with a history of cough syncope exhibited Mobitz type II atrioventricular block with a narrow QRS complex on Holter monitoring. The baseline electrophysiologic study was normal. No significant atrioventricular block could be induced with carotid sinus massage, neck suction, or intravenous propranolol. However, coughing reproduced Mobitz type II atrioventricular block, which was found to be above the His bundle on the His bundle electrogram. A review of the mechanism of cough syncope is also presented.