Properties of Dual AV Nodal Pathways in Patients with Paroxysmal AV Nodal Reentrant Tachycardia

ABSTRACT

Anterograde and retrograde conduction properties of dual AV nodal pathways were analyzed in 15 patients having no accessory pathway and showing dual AV nodal pathways during extrastimulation. Four patients in whom the supraventricular tachycardia of common type (common type SVT) was induced during electrophysiological study were classified into group A. The remained 11 patients in whom the common type SVT was not induced were classified into group B. There was a history of paroxysmal supraventricular tachycardia(PSVT) in all of group A but none of group B. Among the properties of dual AV nodal pathways, effective refractory period (ERP) of anterograde fast pathway (FP) and retrograde FP were not different in both group. Maximal AH interval of anterograde slow pathway (SP) was significantly shorter in group A than in group B (P<0.01). In group A, all patients had intact ventriculoatrial (VA) conduction, but in group B, 5 patients had no VA conduction. The paced atrial cycle length producing Wenckebach block (WBCL) and the paced ventricular cycle length producing retrograde VA block (VABCL) were significantly shorter in group A the in group B (p<0.05). There were two patients showing retrograde dual AV nodal pathways. The common type SVT was not induced in both of them probably due to long ERP of retrograde FP. In conclusion, in patients with anterograde dual AV nodal pathways, the occurrence of common type SVT is highly related to anterograde slow pathway refractoriness (WBCL) and retrograde fast patway refactoriness (VABCL).