[Adult familial idiopathic binodal block].

Four brothers with a maximum age difference of 20 years, the eldest of whom has been re-examined after a 10 year interval, have sinoatrial block, a supra-hisian atrioventricular block and paroxysmal atrial arrhythmias which have led to partial atrial standstill in the eldest: left anterior hemiblock is also present in the two youngest brothers. The condition is very well tolerated. This family is compared to the other 12 reported cases of familial idiopathic binodal block in the adult, an autosomal dominant condition with variable penetration. The diagnosis is reserved and justifies endocavitary investigation of the sinus node function and atrioventricular conduction in the four brothers and the most exposed members of their family. The mechanism of the condition is unknown. It seems to arise from variable degrees of nonspecific of the nodal and atrial tissues.