心室流出道室性心动过速的电生理学基础

Electrophysiological Mechanism of Left Ventricular Outflow Tract Tachcardic

目的 研究心室流出道的电生理特性及其与室性心动过速的关系。方法 利用细胞内微电极记录技术 ,观察豚鼠左心室流出道组织的电活动特性。结果 (1)在 32例豚鼠左室流出道组织标本中 6例 (18 75 % )未经电刺激即可记录到自律性电活动 ,2 3例 (71 88% )在常规电刺激诱导下也可出现自律性电活动。 (2 )在左心室流出道记录到的动作电位形态呈多样性 ,可分为 3大类 :①上升支缓慢、幅值小且 4相自动去极化明显的自律性慢反应电位 ,其特征与窦房结慢反应自律细胞动作电位相似 [APA :(5 0 2 3± 13 5 6 )mV ,Vmax :(10 0 3± 6 32 )V/s,VDD :(33 36± 6 38)mV/s],记录部位为紧靠瓣膜下及流出道光滑部的局部区域 ;②非自律性慢反应电位 ,其上升支缓慢、幅值小无 4相自动去极化 [APA :(6 3 2 6± 17 33)mV ,Vmax :(18 2 7± 8 33)V/s],分布在慢反应自律细胞的周围及相邻的局部区域 ;③非自律性快反应电位 ,其特征与普通心室肌细胞动作电位相似 [APA :(88 32± 6 86 )mV ,Vmax :(10 9 6 0± 8 6 2 )V/s],流出道的大部分组织为此类电位。各类型动作电位的 0相去极化速度、幅度及动作电位时程均变异较大。结论 心室流出道组织的电生理特性与普通心室肌不同 ,具有明显的自律性和电生理各向异性 ,我们认为这?

Objective To study the electrophysiological characteristics and its role in left ventricular outflow tract(LVOT) tachycardia of guinea pigs.Methods Action potentials in LVOT cells were recorded using intracellular microelectrode technique.Results (1)Spontaneous activity could be recorded in 6 preparations out of 32 (18.75%),while in 23 preparations (71.88%) automatic activity could be induced by electrical stimulation.(2) The action potentials of LVOT showed three types:①Spontaneous slow action potentials recorded from local areas below the aortic valves,which showed a slow and low rising phase and a marked spontaneous depolarization in phase 4[APA:(50.23±13.56)mV,Vmax:(10.03±6.32)V/s,VDD:(33.36±6.38)mV/s];②No-spontaneous slow action potentials recorded from the same regions,it showed a slow rising phase but no marked spontaneous depolarization in phase 4[APA:(63.26±17.33)mV,Vmax:(18.27±8.33)V/s];③Fast action potentials recorded from most regions of LVOT[APA:(88.32±6.86)mV,Vmax:(109.60±8.62)V/s].Conclusion The result indicates that Guinea-pig lift ventricular outflow tract possessing automaticity and electrophysiological heterogeneity,This may be applied to interpret ventricular outflow tract arrhythmia.