Hypertrophic subaortic stenosis complicated by high degree heart block: successful treatment with an atrial synchronous ventricular pacemaker.

The development of high degree atrioventricular block in a patient with hypertrophic subaortic stenosis underscores the importance of a properly timed atrial contraction in this disorder. Atrial synchronous ventricular pacing therapy, by providing, reliably timed atrial systole and increased left ventricular end-diastolic volume, has an important role in this patient and in similar cases.