房室结折返性心动过速的可激动间隙及分区

目的探讨典型的房室结双径路引起的房室结折返性心动过速(AVNRT)可激动间隙的特点及其分区。方法25例AVNRT患者心动过速发作后,分别在右室心尖部和高位右房给予VS2和AS2早搏刺激,从心动过速周长-10ms开始刺激,相隔8个心动过速周期,以-10ms的步长进行递减扫描,测定可激动间隙,并与41例房室折返性心动过速(AVRT)患者比较。结果25例AVNRT患者中,2例经右心房AS2刺激可以使心动过速重整,仅2例患者可经心房AS2刺激使心动过速终止,3例经心室VS2刺激可以使心动过速重整,经心室VS2刺激均未能使心动过速终止,与AVRT患者比较有显著性差异(P<0.05)。心动过速重整时,偶联间期与回归间期之和可小于心动过速周长的2倍,亦可等于心动过速周长的2倍。结论刺激部位不同,折返环不同,所暴露的可激动间隙可能不同。刺激的偶联间期与回归间期之和等于心动过速周长的2倍,不能排除心动过速的重整。

Excitable Gap and Subdivision of Atrioventricular Nodal Reentrant Tachycardia

Objective To investigate the characteristics of atrioventricular nodal reentrant tachycardia (AVNRT) and its classification. Methods Excitable gap (EG) was determined in 25 AVNRT patients by series VS2 or AS2 premature stimuli which started from cycle length -10 ms with decremental distance of -10 ms. Forty-one patients with atrioventricular reentrant tachycardia (AVRT) were selected as controls. Results Among 25 cases of AVNRT, resetting was observed in 2 by AS2 stimuli at the right atrium, and in 3 by VS2 at the right ventricle. Termination was observed in 2 by AS2 stimuli at the right atrium, and none by VS2 at the right ventricle. Exposed EG stimulated in the atrium was different from that stimulated in the ventricle, and incidence of resetting of AVNRT was different from that of AVRT. Conclusion Exposed EG might vary with different reentrant circuits as well as different pacing sites. Resetting of tachycardia could not be excluded when the sum of coupling intervals and return cycle equals to twice cycle length of tachycardia.