Nearing B D, Oesterle S N, Verrier R L
Georgetown University School of Medicine and Hospital, Washington, DC 20007.
Cardiovasc Res. 1994 Sep;28(9):1440-9. doi: 10.1093/cvr/28.9.1440.
The aim was to examine the regional specificity of T wave alternans and the value of precordial ECG monitoring for non-invasive tracking of cardiac vulnerability during acute coronary artery occlusion and reperfusion in animals and humans.
The left ventricular ECG was monitored during two acute occlusions of the left anterior descending coronary artery and subsequent reperfusion in each of 61 chloralose anaesthetised dogs, and over 150,000 beats were analysed. In subgroups of these animals, lead II and precordial lead V5 were monitored or epicardial electrograms were recorded. In seven patients, lead II and precordial leads V1-6 were monitored during angioplasty. T wave alternans magnitude was quantified by complex demodulation. The same recording equipment and analytical methods were used in the clinical and experimental studies.
A close temporal correspondence and linear correlation was found between T wave alternans magnitude--but not ST segment depression or ventricular premature beat incidence--and the incidence of spontaneous ventricular tachycardia and fibrillation during acute coronary artery occlusion and reperfusion. Epicardial electrograms showed alternans to be regionally specific, occurring in the ischaemic but not in the normal zones, and to predict spontaneous ventricular fibrillation and ventricular tachycardia (sensitivity = 79%, specificity = 86%). A significant linear relationship (r2 = 0.86, p < 0.01) between alternans magnitude detected in V5 and the left ventricular intracavitary lead indicates that the precordial leads could be used to assess cardiac vulnerability from the body surface. Lead V5 showed greater resolution than lead II. In humans, the precordial leads overlying the ischaemic zone were superior to lead II or Frank leads for alternans detection during both the occlusion and the reperfusion phases. In both animals and humans, alternation invariably occurred during the first half of the T wave, coinciding with the vulnerable period of the cardiac cycle and suggesting an important electrophysiological link to cardiac vulnerability.
Alternans is regionally specific and is linearly projected to the precordium. Quantification of its magnitude in the precordial ECG may provide a non-invasive means for tracking cardiac vulnerability during acute myocardial ischaemia and reperfusion in both animals and humans.
本研究旨在探讨T波交替的区域特异性，以及胸前心电图监测在动物和人类急性冠状动脉闭塞及再灌注期间无创追踪心脏易损性方面的价值。
在61只水合氯醛麻醉的犬中，于左前降支冠状动脉两次急性闭塞及随后的再灌注过程中监测左心室心电图，并分析超过150,000次心跳。在这些动物的亚组中，监测II导联和胸前导联V5，或记录心外膜电图。在7例患者中，于血管成形术期间监测II导联和胸前导联V1 - 6。通过复解调对T波交替幅度进行量化。临床和实验研究使用相同的记录设备和分析方法。
在急性冠状动脉闭塞及再灌注期间，发现T波交替幅度（而非ST段压低或室性早搏发生率）与自发性室性心动过速和颤动的发生率之间存在密切的时间对应关系和线性相关性。心外膜电图显示交替具有区域特异性，发生于缺血区而非正常区，并可预测自发性室颤和室性心动过速（敏感性 = 79%，特异性 = 86%）。在V5导联检测到的交替幅度与左心室内腔导联之间存在显著的线性关系（r2 = 0.86，p < 0.01），表明胸前导联可用于从体表评估心脏易损性。V5导联比II导联具有更高的分辨率。在人类中，缺血区上方的胸前导联在闭塞期和再灌注期检测交替方面均优于II导联或Frank导联。在动物和人类中，交替均始终发生在T波的前半部分，与心动周期的易损期一致，提示与心脏易损性存在重要的电生理联系。
交替具有区域特异性，并线性投射至胸前区。量化胸前心电图中其幅度可为在动物和人类急性心肌缺血及再灌注期间追踪心脏易损性提供一种无创方法。
