在电压范围测量的心室复极离散

利用单相动作电位 (MAP)技术描述一种在电压范围内测量心室复极空间离散的新方法。 10个均匀分布的MAP电极 ( 2个位于心内膜、8个位于心外膜 )在 8只离体Langendorff灌流兔心脏上同步记录MAP信号。电压范围的复极离散定义为 3相复极期间某一时刻不同部位MAP复极百分比最大与最小值之差。每隔 10ms计算一次电压离散值并以此构建离散曲线。结果 :将测得的复极离散值对复极时间作图得到一条离散曲线 ,其特点为 :离散在复极早期呈逐渐增加的趋势 ,达到峰值后开始下降 ,并在复极晚期降至趋向于零。为检测此方法的实用性 ,我们比较了离散曲线与双相T波电击易损窗的关系后发现 ,易损窗占绝对优势地发生在离散值高的时候 ,并且曲线的峰值与易损窗的左沿密切相关 (r=0 .95 ,P <0 .0 1)。另外 ,心肌缺血使离散曲线高度增加 ,峰值左移 ,同时易损窗的宽度增加。结论 :电压范围的复极离散可为我们提供一种新的测量复极非均一性的手段 ,从而有助于更好地理解心律失常易感性

Dispersion of the Ventricular Repolarization in the Voltage Domain

A novel method to measure spatial dispersion of repolarization in the voltage domain was described using monophasic action potential (MAP) technique.10 evenly spaced MAP electrods (2 at endocardium,8 at epicardium) were used to simultaneously record MAP in eight Langendorffperfused rabbit hearts.The dispersion of repolarization in the voltage domain was defined as the difference between the most and least completely repolarized MAPs at a given time during phase 3 of the repolarization process.The voltage dispersion was calculated every 10 ms during the repolarization process which allowed us to construct individual “dispersion curves”.Results:The dispersion curves had a characteristic shape:dispersion increased during early repolarization,reached a peak,and thereafter declined towards zero.To test the feasibility of our approach we studied the relationship between the dispersion curve and the vulnerable window (VW) for biphasic shocks and found that the VW occurred predominantly during high voltge dispersion and the curve peak was closely correlated with the left border of VW (r=0.95,P<0.001).Meanwhile,ischemia caused an increase of the dispersion cueve peak and the left shift of the curve peak along with an increase of the width of VW.Conclusions:Dispersion in the voltage domain provides a novel measure for the heterogeneity of repolarization.This may help to better understand arrhythmia susceptibility.[Chinses Journal of Cardiac Pacing and Electrophysiology,2000,14(2):113～116] Dispersion of the ventricular repolarization in the voltage domain Monophasic action potential Vulnerable window Ischemia Rabbit