[Evaluation of pulmonary capillary wedge pressure tracing for the detection of intraoperative myocardial ischemia].

We studied the usefulness of the pulmonary capillary wedge pressure (PCWP) tracing for the detection of intraoperative myocardial ischemia. Both PCWP wave forms and 7-lead electrocardiogram were monitored in 109 patients undergoing coronary artery bypass graft surgery. Measurements were made six times in each patient. Myocardial ischemia was identified in 99 (27%) of the 366 measurements, and among them, 68 (69%) developed abnormal PCWP wave forms (AC wave greater than 15 mmHg, or V wave greater than 20 mmHg). Although these results were consistent with those of Kaplan et al (1981), we could not agree with their conclusion that PCWP tracing can be helpful in the early diagnosis of subendocardial ischemia. It was not possible to record PCWP continuously because of the risk of pulmonary infarction, and PCWP was influenced by noncardiac factors such as sympathetic reaction to surgical stimuli. We think that PCWP tracing would be of benefit in detecting intraoperative serious ischemia; serious myocardial ischemia was likely to have occurred when abnormalities in both PCWP tracing and ST segment changes were identified. The incidence of both PCWP changes and ECG ischemia was highest in the postbypass period, suggesting that the risk of serious myocardial ischemia is highest in the post-bypass period.