[Familial bradycardia: a family with sick sinus and atrioventricular block].

A kindred is described in which several members have evidence of sick sinus syndrome and of conduction disturbance. The data suggest that in this family the rhythm disturbances were transmitted as an autosomal dominant trait whose penetrance increase with age. The occurrence of Adams-Stokes episodes required pacemaker implantation in 6 patients. In one case the arrhythmia is associated with a cardiomyopathy of unknown origin. No pathological studies were conducted. In one case the His bundle electrogram was recorded.