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Ann Thorac Surg 2004;77:1293-1297
© 2004 The Society of Thoracic Surgeons

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Original article: cardiovascular

High-frequency QRS potentials as a marker of myocardial dysfunction after cardiac surgery

^a Department of Surgery, University of Tsukuba, Institute of Clinical Medicine, Tsukuba, Japan

Accepted for publication September 11, 2003.

^* Address reprint requests to Dr Matsushita, Department of Surgery, Institute of Clinical Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
e-mail: shomatsu{at}md.tsukuba.ac.jp

BACKGROUND: 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.

METHODS: 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).

RESULTS: 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.

CONCLUSIONS: 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.

This article has been cited by other articles:

				S. Matsushita and Y. Sakakibara Did the Global Myocardial Ischemia Produce an Influence On High-Frequency QRS Potentials: Reply Ann. Thorac. Surg., October 1, 2005; 80(4): 1564 - 1564. [Full Text] [PDF]

				Y. Terada Did the Global Myocardial Ischemia Produce an Influence On High-Frequency QRS Potentials? Ann. Thorac. Surg., October 1, 2005; 80(4): 1563 - 1564. [Full Text] [PDF]