The clinical and electrophysiologic characteristics of patients with accelerated atrioventricular nodal conduction.

The clinical and electrophysiologic features of 42 patients found to have rapid atrioventricular (AV) nodal conduction during electrophysiologic study are described. The distinctive clinical feature of these patients was the high incidence of supraventricular tachycardias, which were rapid and had been poorly responsive to conventional antidysrhythmic treatment. Abnormalities of both AV nodal conduction and AV nodal refractoriness were present. Medical management and late follow-up were characterized by inconsistent control of rhythm. In four patients, control of the tachycardia was finally achieved by successful ablation of an accessory extranodal pathway that participated in macro-reentry paroxysmal supraventricular tachycardia. In a fifth patient, the tachycardia was controlled with the use of a patient-activated radiofrequency atrial-stimulating pacemaker. Although the existence of shortened AV nodal conduction time and refractoriness may not cause supraventricular rhythm disturbances, symptoms are aggravated by resultant rapid ventricular rates. Treatment for patients with this anatomic-functional substrate must be highly individualized and be based on electrophysiologic investigation. Newer treatment modalities with investigational medications, pacing techniques, and surgical approaches may play an important role in the management of these patients.