维拉帕米治疗房室折返性室上性心动过速的电生理和药理学观察

Electropharmacologic eflfects of verapamil on patients with atrioven-tricular reciprocating tachycardia

We evaluated efficacy and mechanisms of antiarrhythmic action of verapamil on 32 patients with the or -thodromic form of AV reciprocating tachycardia (AVRT) complicated with the Wolff-Parkinson-White syndrome. During sinus rhythm, verapamil prolonged AH interval and the antegrade effective refractory period (ERP ) of the AV node and shortened the antegrade ERP of the accessory pathway, but it exerted no significant effects on the ERPs of the atrium and the ventricle, HV interval, the retrograde ERP of the accessory pathway and the sinus cycle length did not change significantly by sympathetic activation. During AVRT, verapamil significantly prolonged the cycle length of AVRT and AH interval, but HV interval remained unchanged and VA interval did not change significantly. Intravenous administration of verapamil terminated 88% of AVRT in the group. Termination of AVRT had the following characteristics: (1) The rate of AVRT decreased gradually after administration of verapamil and it decreased by about 15% at termination. (2) Invariably, the site of AVRT interruption was in the AV node. (3)The half of the cases manifested alternation of short and long cycle lengths before conversion to sinus rhythm. The result of electropharmacologic testing showed that verapamil might have success rate of 72% in preventing occurrence of AVRT, but infusion of epinephrine reversed its effect on the induction of AVRT in 83% of the cases.