电击引起的心室复极离散在心室颤动诱发和易损上限形成中的作用

Shock induced dispersion of repolarization is essential for the induction of ventricular fibrillation by T wave shocks

目的 应用单相动作电位（ＭＡＰ）技术，系统研究Ｔ波电击引起的复极离散（ＳＩＤＲ）与诱发心室颤动（ＶＦ）的关系。方法 截尾指数为６５％ ／６５％ ，脉宽５ ｍ ｓ的双相电流，以电击强度与配对间期的随机组合施加于稳态起搏的Ｌａｎｇｅｎｄｏｒｆｆ离体灌流家兔心脏的舒张期。８ 个心外膜和２ 个心内膜位点同步记录ＭＡＰ。ＳＩＤＲ定义为ＭＡＰ同步记录中最长与最短电击后复极时间之差。结果 诱发ＶＦ的电击引起的ＳＩＤＲ为（６４±１５）ｍ ｓ，但当配对间期分别移出易损窗口左右沿各１０ ｍ ｓ 后，ＳＩＤＲ显著变小，其值分别为（３３±１４）ｍ ｓ和（２７±８）ｍ ｓ（与诱发ＶＦ电击比，二者皆Ｐ＜ ０．００１）。当配对间期位于易损窗口内，但电击强度高于易损上限（ＵＬＶ）时，ＳＩＤＲ显著变小，其值为（４１±１７）ｍ ｓ（与诱发ＶＦ的电击相比，Ｐ＜ ０．０１）。

Objective Shock induced dispersion of repolarization (SIDR) measured by multiple monophasic action potential (MAP) recordings and its relashingship to the induction of ventricular fibrillation (VF) by T wave shocks were studied. Methods Biphasic shocks (65/65% tilt,5 ms duration) were delivered to Langendorff perfused rabbit hearts at shock coupling intervals (CI) ranging from 150～220 ms and shock strengths (SS) ranging from 140～540V.Ten MAPs were recorded simultaneously from 8 epicardial and 2 endocardial sites from both ventricles to assess SIDR at multiple sites.SIDR was defined as the difference between the longest and shortest shock induced MAP response. Results VF induction was associated with high SIDR (64±15) ms.There was a significant decrease in SIDR as shock coupling intervals moved outside the borders of the vulnerable window (VW)[(33±14) ms left of the VW and (27±8) ms right of the VW,both P <0.001].For shocks within the VW,SIDR significantly decreased when SS reached values at or above the upper limit of vulnerability (ULV) [(41±17) ms, P <0.01] Conclusion T wave shocks which induce VF are associated with a high degree of SIDR.