Intrahisian block in cardiomyopathy.

Two patients with cardiomyopathy and intrahisian atrioventricular [A-V] block are described. The first patient with underlying non-obstructive hypertrophic cardiomyopathy had split His bundle potentials only during atrial pacing and presented associated conduction abnormalities: enhanced A-V nodal conduction and sick sinus syndrome. The second patient had progressive muscular dystrophy and a complete intrahisian A-V block. Attention is called to the possible interrelationship between different conduction abnormalities and to their clinical implications.