The value of cross-sectional echocardiography in detecting perioperative myocardial infarction following coronary artery bypass graft surgery

Segmental Wall-Motion Abnormalities After an Arterial Switch Operation Indicate Ischemia

We prospectively studied 29 consecutive neonates undergoing an arterial switch operation to determine if segmental wall motion abnormalities (SWMA) represented myocardial ischemia. Intraoperative transesophageal echocardiogram was recorded at baseline and twice after cardiopulmonary bypass. Cardiac troponin I (cTnI) levels were measured before sternal incision and 3, 6, 12, 24, 48, and 72 h after removal of the aortic cross-clamp. Immediate postoperative Holter and 15-lead electrocardiograms (ECG) were evaluated for ischemia. Transthoracic echocardiograms were obtained before hospital discharge. At bypass termination, immediately after protamine administration, segmental wall motion was normal in nine neonates and abnormal in 20. SWMA were transient in five and present at the time of chest closure in 15 neonates. Neonates in whom SWMA were present at chest closure had more segments involved than those in whom SWMA were transient (P > 0.001). Neonates with SWMA at chest closure had higher cTnI levels postoperatively versus neonates with normal wall motion (P = 0.02). Postoperative ECG data were available in 26 neonates. There was ECG evidence of myocardial ischemia in two of eight neonates with normal wall motion, one of five with transient SWMA, and nine of 13 with SWMA at chest closure. CTnI levels at 12, 24, and 48 h and intraoperative SWMA were predictive of postoperative SWMA. We believe these data indicate that SWMA, which persist at the completion of an arterial switch operation, and which are present in multiple myocardial segments, correlate with myocardial ischemia. Further follow-up of these patients is needed to determine if increased intraoperative myocardial ischemia correlates with long-term outcomes.

Effects of coronary artery surgery on left ventricular performance, segmental wall movement, and exertional ischaemia

The effects of coronary artery surgery on left ventricular performance were assessed serially by echocardiography and treadmill exercise testing in 54 patients. Patients were assessed one day before operation and again before patients left hospital (mean 10 days after operation) and one month and six months after operation. At the predischarge assessment, 41 (77%) patients showed new abnormalities of left ventricular segmental wall movement, chiefly anteroseptal hypokinesia with hyperkinesia of the posterolateral segment. Although there were no significant changes in anteroseptal wall thickening after operation, there was a significant increase in posterior wall thickening at all postoperative assessments. The frequency of this abnormality decreased progressively after operation; it persisted in 19 (35%) patients at six months. Left ventricular fractional shortening decreased after operation and at one month was significantly less than before operation. There were no significant changes in left ventricular diastolic diameter during the study. Haemodynamic function during exercise, the duration of exercise, and features of reversible myocardial ischaemia all improved progressively and significantly after coronary artery surgery. Abnormalities in left ventricular segmental wall movement and thickening commonly develop early after coronary artery surgery but tend to resolve by six months and do not seem to impair left ventricular contractility at rest or exercise performance and haemodynamic function. Recognition of these echocardiographic changes may be clinically important in the assessment of patients after cardiac surgery.