Significance of exercise-induced second degree atrioventricular block.

A case of second degree, type II, atrioventricular block precipitated by exercise is presented. It is suggested that exercise and other vagolytic manoeuvres may be used as a means of differentiating type I from type II atrioventricular block: the conduction disturbance of type I improves with exercise, whereas that of type II deteriorates with exercise.