[Spontaneous blocks by intra-atrial conduction disorders of reciprocating atrioventricular rates using a Kent's bundle].

Paroxysmal tachycardia in Type A Wolff-Parkinson-White syndrome was due to a reciprocating rhythm involving a left lateral Kent Bundle in the retrograde direction. Spontaneous interruption of the reentry resulted not from block in the normal or accessory atrioventricular pathways but from an intraatrial conduction defect: delay in conduction between the left and right atria on intraatrial reentry terminated the tachycardia.