Downar E, Saito J, Doig J C, Chen T C, Sevaptsidis E, Masse S, Kimber S, Mickleborough L, Harris L
Division of Cardiology, Toronto General Hospital, Ontario, Canada.
J Am Coll Cardiol. 1995 Jun;25(7):1591-600. doi: 10.1016/0735-1097(95)00086-j.
This study was conducted to characterize the functional nature of the reentrant tract responsible for ventricular tachycardia due to ischemic heart disease.
A zone of slow conduction forming the return path is though to form a critical component of the reentrant mechanism in ventricular tachycardia. Despite its importance, detailed knowledge of the return path is rare in clinical studies.
Multielectrode arrays were used intraoperatively to obtain unipolar and high gain bipolar recordings of left ventricular endocardium in patients undergoing map-directed surgical ablation of ventricular tachycardia. A total of 224 local electrograms were analyzed for each tachycardia.
Of 10 consecutive patients undergoing intraoperative cardiac mapping, detailed recording of the return tracts of eight ventricular tachycardias were obtained in three patients. The recordings demonstrated that return tracts can be complex and extensive, with multiple paths of entry and exit. Potential and actual alternate paths were observed. Spontaneous and induced block occurred within portions of the complex. Intermittent block in one of two paths of entry resulted in intermittent cycle length changes of the tachycardia without a change in configuration. Block in one exit path resulted in a shift to alternative exit paths, with dramatic changes in ventricular activation and tachycardia configuration. Termination of the tachycardia could result from block close to the entrant or exit portion of the return tract. Different tachycardias were seen to share common portions of a return tract.
These observations enlarge and extend our knowledge of the functional repertoire of complex reentrant tracts that occur in infarct-related ventricular tachycardia. The use of common portions of a reentrant tract by several tachycardias is confirmed. Utilization of alternate pathways can account for changes in configuration and cycle length. Spontaneous and induced block can occur at points of entry and exit in a reentrant tract and may identify optimal targets for ablation attempts. Further advances will require greater emphasis on diastolic activation mapping.
本研究旨在描述缺血性心脏病所致室性心动过速折返径路的功能特性。
形成折返路径的缓慢传导区被认为是室性心动过速折返机制的关键组成部分。尽管其很重要，但在临床研究中对折返路径的详细了解却很少。
在接受室性心动过速标测指导下手术消融的患者中，术中使用多电极阵列获取左心室心内膜的单极和高增益双极记录。对每次心动过速共分析224份局部电图。
在连续10例接受术中心脏标测的患者中，3例患者获得了8次室性心动过速折返径路的详细记录。记录显示折返径路可能复杂且广泛，有多个出入路径。观察到潜在和实际的交替路径。在复合体的部分区域发生了自发和诱发的阻滞。两条入口路径之一的间歇性阻滞导致心动过速的周期长度间歇性改变，而形态无变化。一条出口路径的阻滞导致转向替代出口路径，心室激动和心动过速形态发生显著变化。心动过速的终止可能是由于折返径路入口或出口附近的阻滞。不同的心动过速可见共享折返径路的共同部分。
这些观察结果扩展了我们对梗死相关室性心动过速中复杂折返径路功能谱的认识。证实了几种心动过速可使用折返径路的共同部分。利用交替路径可解释形态和周期长度的变化。自发和诱发的阻滞可发生在折返径路的出入点，可能确定消融尝试的最佳靶点。进一步的进展将需要更加强调舒张期激动标测。
