Accessory atrioventricular pathways that conduct only in the antegrade direction.

Abstract

Patients with accessory atrioventricular pathways that conduct only in the antegrade direction represent an unusual variant of the Wolff-Parkinson-White syndrome. This report describes such patients and compares them with patients with accessory pathways that demonstrate bidirectional conduction. Of 143 patients with single accessory pathways, seven demonstrated exclusive antegrade conduction (study group), 111 demonstrated bidirectional conduction (control group), and 25 demonstrated exclusive retrograde conduction. Study group patients were significantly older than patients in the control group (42 +/- 9.8 years and 31.4 +/- 13.9 years, respectively, p < 0.0001). Refractoriness and conduction characteristics of the accessory pathways in the antegrade direction in the study group were not different from those in the control group. Control group patients presented with atrioventricular reentrant tachycardia (58 of 111), atrial fibrillation (23 of 111), both of these arrhythmias (19 of 111), or no documented arrhythmia (11 of 111). Study group patients presented with only atrial fibrillation (six of seven). An accessory pathway with only antegrade conduction is a rare cause of symptoms in the Wolff-Parkinson-White syndrome. These patients are asymptomatic until atrial fibrillation develops as the patient ages. Despite the absence of retrograde conduction over the accessory pathway, its antegrade functional properties are similar to pathways that demonstrate bidirectional conduction.