Multiple accessory pathways in patients with the pre-excitation syndrome.

Abstract

Patients [135] with the pre-excitation syndrome were studied and evidence of multiple accessory pathways was shown in 20 patients. Five patients had 2 distinct accessory atrioventricular (A-V) connections, associated with enhanced A-V node conduction in 1 patient. Twelve patients had a single accessory A-V connection associated with enhanced A-V conduction. In 1 of these there was an additional fasciculo-ventricular connection. One patient had an accessory A-V connection associated with a nodo-ventricular bundle. Two patients had fasciculo-ventricular connections combined with enhanced A-V conduction. The latter 2 patients had electrocardiograms suggestive of a complete A-V connection. Patients with enhanced A-V conduction had shorter cycle lengths during reciprocating tachycardia, primarily because of a short A-H during the dysrhythmia, than those without such conduction. Patients with enhanced A-V conduction demonstrated more rapid conduction from atrium to His bundle during induced atrial fibrillation and 2 developed life-threatening ventricular responses during atrial fibrillation. A nodo-ventricular pathway was documented to participate in reciprocating tachycardia in 1 patient. Surgery was undertaken in 13 patients. In 11, the intraoperative mapping studies confirmed the preoperative predictions. In 2 patients, the presence of a 2nd accessory A-V connection was documented after ablation of 1.