[Chronic idiopathic binodal block. Occurrence, course and pathogenesis].

The incidence of binodal, sinoatrial (SA) and atrioventricular (AV), block was determined in a series of 362 patients, 90 of whom had chronic sinoatrial block (group I), 162 suprahisian, infrahisian or diffuse AV block (group II), 38 with paroxysmal supraventricular tachycardia (group III), and 70 with slow atrial fibrillation, 54 of whom were studied in sinus rhythm (group IV). Electrophysiological investigation revealed: overt or latent AV block in 71% of group I, 48% of group III, and 100% of group IV; overt or latent SA block in 40 to 61% of group II, 87% of group III and 78% of group IV; paroxysmal atrial fibrillation in 61% of group I, 25% of group II and 50% of group IV; intra-atrial block in 26% of group I, 20% of group II, 16% of group III and 31% group IV. An ECG syndrome associating binodal block and disturbances or atrial conduction and excitability is suggested. The pathogenesis and anatomical basis are discussed, the prime lesion of which may be fibrosis of the atrial tissues which may ultimately result in partial or total atrial standstill.