Determinants of atrioventricular reentrant paroxysmal tachycardia in patients with Wolff-Parkinson-White syndrome.

Abstract

Normal and anomalous pathway properties were evaluated in 50 patients with preexcitation to discover determinants of paroxysmal supraventricular tachycardia (PSVT). Patients (28) had inducible PSVT and 22 had no inducible PSVT. Patients with inducible PSVT had the ability for retrograde anomalous pathway conduction demonstrated with ventricular pacing at short paced cycle lengths (< 429 ms) and close coupling intervals (< 400 ms); and antegrade AV [atrio-ventricular] nodal refractoriness less than anomalous pathway refractoriness during rapid and/or coupled atrial pacing with ability for exclusive normal pathway conduction for at least 1 beat at short atrial paced cycle lengths (< 375 ms) or close coupling intervals (< 320 ms). Failure to induce PSVT was possibly accounted for by absent or poor retrograde anomalous pathway conduction alone (6 patients); inadequate antegrade AV nodal properties alone (8 patients); both inadequate antegrade AV nodal and retrograde anomalous pathway properties (7 patients); and in prolonged atrial refractoriness (1 patient). There were no significant differences in anomalous pathway antegrade refractory periods between patients with and without PSVT. Apparently the occurrence of PSVT in Wolff-Parkinson-White syndrome depends on the ability for retrograde anomalous pathway conduction and adequate antegrade AV nodal conduction. The inability to induce PSVT usually reflects inadequate retrograde anomalous and/or antegrade normal pathway properties. The ability to induce PSVT is independent of antegrade anomalous pathway properties.