[Left ventricular systolic time intervals during paroxysmal supraventricular tachycardia: the difference between A-V nodal re-entry and A-V re-entry].

In this study, the differences in hemodynamic changes during paroxysmal supraventricular tachycardia (PSVT) between A-V nodal re-entry and A-V re-entry were evaluated. In 8 patients with A-V nodal re-entrant tachycardia and 10 with A-V re-entrant tachycardia, electrophysiological studies were performed to measure systolic time intervals (pre-ejection period: PEP, ejection time: ET, PEP/ET ratio: PEP/ET). These measurements were obtained in the control state (atrial pacing at 90/min) and during PSVT with simultaneous recordings of electrocardiogram and femoral arterial pulse tracing. During PSVT, there was no difference in the heart rate between the 2 groups, but ventriculo-atrial conduction time was shorter in A-V nodal re-entry than in A-V re-entry. There was a marked fall in the ET and an increase in PEP/ET in all the patients when PSVT was induced. PEP increased significantly in A-V nodal re-entry, but did not change in A-V re-entry. This resulted in a greater increase in the PEP/ET suggesting a greater deterioration of the hemodynamic consequences in A-V nodal re-entry than in A-V re-ent y. Thus, the hemodynamic changes of PSVT differ between these 2 types of re-entrant circuits, which are mainly influenced by the ventriculo-atrial conduction time.