Response to Exercise in Congenital Complete Atrioventricular Block

Abstract

The electrocardiographic and hemodynamic responses to graded exercise in 11 patients with congenital complete atrioventricular block are described. Ventricular rate increases during exercise were unrelated to the resting rate, atrial rate, or heart size. Changes in the ratio of atrial: ventricular rates were observed in all cases during physical work. Physical working capacity was normal or only slightly reduced in all instances. This is accomplished through maintenance of normal minute volumes, which in turn reflects an interplay of several factors: acceleration of ventricular rate, increased heart volume and stroke volume, and a normal or supernormal oxygen-transporting capacity of the blood as reflected in increased amount of total hemoglobin.