EXERCISE-INDUCED ATRIOVENTRICULAR-BLOCK REVISITED - CASE-REPORT AND REVIEW

Exercise causes enhanced sympathetic discharge and results in physiolo gic tachycardia. However, in certain patients with a diseased conducti on system, exercise can precipitate heart block. The sinus and atriove ntricular nodes are innervated by the autonomic nervous systems. The H is-Purkinje system is relatively devoid of autonomic nerve supply. Hen ce the former and not the latter is influenced more by autonomic stimu lation. During exercise, conduction improves across the atrioventricul ar node which can stress the His-Purkinje system and lead to heart blo ck in those with significant His-Purkinje disease. In this report, we discuss a recent case of exercise-induced heart block confirmed by ele ctrophysiology study and briefly review this subject.