Familial atrioventricular heart block - an autosomal dominant trait

Abstract

A family of 28 individuals spanning 4 generations was investigated because of a finding of complete heart block in 5 members and the existence of a low degree of atrioventricular (AV) heart block in a sixth member. The disorder was characterized by adult onset in all; complete AV heart block in 5; and first degree AV heart block in one; sinus bradycardia in 3; atrial fibrillation in 5; abnormal QRS complex in 5; ventricular tachycardia in 3; left ventricular enlargement in all; and mitral insufficiency in 5. Proximal location of the AV heart block was suggested by the fact that atropine caused acceleration of the ventricular rate and by the presence of a His bundle potential preceding the QRS complexes. Involvement of the distal conducting system was indicated by the widened QRS complex and a prolonged HV interval. Pathologic examination in one case showed extensive sinus node fibrosis and interruption of the AV node His bundle connection. This disorder is probably due to an autosomal dominant trait.