Cough syncope due to atrio-ventricular conduction block.

A case of cough syncope due to A-V conduction block of the heart is reported in this paper. A-V conduction block and lightheadedness were induced by coughing but not by an Aschner test, carotid sinus massage, Valsalva maneuver, pharyngeal stimulation, and stimulation of systemic baroreceptors. Permanent right-ventricular pacing completely abolished the patient's symptoms. The results suggest that hypersensitivity of a broncho-pulmonary reflex to coughing was responsible for the A-V conduction block and resulting syncopes.