Matsushita Shonosuke, Sakakibara Yuzuru, Imazuru Tomohiro, Noma Mio, Hiramatsu Yuji, Shigeta Osamu, Jikuya Tomoaki, Mitsui Toshio
Department of Surgery, University of Tsukuba, Institute of Clinical Medicine, Tsukuba, Japan.
Ann Thorac Surg. 2004 Apr;77(4):1293-7. doi: 10.1016/j.athoracsur.2003.09.088.
High-frequency QRS potentials are sensitive to myocardial ischemia. The aim of this study was to evaluate the usefulness of high-frequency QRS potentials as a marker of myocardial dysfunction after cardiac surgery.
Seventy patients undergoing coronary artery bypass grafting or heart valve surgery were involved. High-frequency QRS potentials were measured by signal-averaged electrocardiogram, and calculated as the root-mean-square voltage of the total QRS duration (RMST). The postoperative RMST was expressed as a percentage of the preoperative RMST. The mean RMST at 1 to 2 hours after removing the aortic cross-clamp was compared with the cardiac index, inotropic agents, and aortic cross-clamping time. The occurrence of ventricular tachycardia within 24 hours and the RMST at 2 postoperative days were also evaluated. Patients were divided into quartile groups from highest to lowest at postoperative RMST (groups 1, 2, 3, and 4, respectively, from maximum to minimum).
In postoperative states, cardiac index significantly decreased in accordance with the RMST decrease in a stepwise manner, although there were no differences in cardiac index among the four groups preoperatively. Inotropic agents and aortic cross-clamping time increased as RMST decreased. A high rate of ventricular tachycardia within 24 hours and delayed RMST recovery at 2 postoperative days were seen in group 4. The curve of sensitivity and specificity showed that severe reduction (threshold, 35%) of RMST indicated low-output syndrome.
The severe reduction of filtered high-frequency QRS potentials was related to myocardial dysfunction. Measurement of filtered high-frequency QRS potentials could become a useful, noninvasive, real-time monitor of myocardial dysfunction after surgery.
高频QRS波电位对心肌缺血敏感。本研究旨在评估高频QRS波电位作为心脏手术后心肌功能障碍标志物的实用性。
纳入70例行冠状动脉旁路移植术或心脏瓣膜手术的患者。通过信号平均心电图测量高频QRS波电位，并计算为整个QRS波时限的均方根电压（RMST）。术后RMST表示为术前RMST的百分比。比较主动脉阻断钳夹去除后1至2小时的平均RMST与心脏指数、血管活性药物及主动脉阻断时间。还评估术后24小时内室性心动过速的发生情况及术后第2天的RMST。根据术后RMST从高到低将患者分为四分位数组（分别为1、2、3和4组，从最大到最小）。
术后状态下，心脏指数随RMST的降低呈逐步显著下降，尽管术前四组的心脏指数无差异。血管活性药物用量及主动脉阻断时间随RMST降低而增加。第4组在术后24小时内室性心动过速发生率高且术后第2天RMST恢复延迟。敏感性和特异性曲线显示，RMST严重降低（阈值为35%）提示低心排血量综合征。
滤波后的高频QRS波电位严重降低与心肌功能障碍有关。测量滤波后的高频QRS波电位可成为术后心肌功能障碍有用的、非侵入性的实时监测指标。
