Exercise-Induced Atrioventricular Block Revisited: Case Report and Review

Exercise causes enhanced sympathetic discharge and results in physiologic tachycardia. However, in certain patients with a diseased conduction system, exercise can precipitate heart block. The sinus and atrioventricular nodes are innervated by the autonomic nervous systems. The His-Purkinje system is relatively devoid of autonomic nerve supply. Hence the former and not the latter is influenced more by autonomic stimulation. During exercise, conduction improves across the atrioventricular node which can stress the His-Purkinje system and lead to heart block in those with significant His-Purkinje disease. In this report, we discuss a recent case of exercise-induced heart block confirmed by electrophysiology study and briefly review this subject.