Detection of myocardial ischemia by transesophageal echocardiographically determined changes in left ventricular area in patients undergoing coronary artery bypass surgery

Abstract

Study Objective: To evaluate left ventricular (LV) dimensions and function during myocardial ischemic episodes in anesthetized patients undergoing coronary artery bypass surgery. Design: Prospective, nonrandomized study. Setting: Large, medical school-affiliated tertiary-care medical center. Patients: 36 adults undergoing elective primary coronary artery bypass surgery. Interventions: Transesophageal atrial pacing for 3 to 5 minutes at heart rates (HRs) of 65, 70, 80, and 90 beats per minute. Measurements and Main Results: Arterial, pulmonary artery, and venous pressures, transesophageal echocardiographic (TEE) determined LV end-diastolic (EDA) and end-systolic (ESA) areas, and fractional area change (FAC = [EDA-ESA]/EDA). Myocardial ischemia determined as at least 1 mm ST segment deviation at J + 60 milliseconds from 12-lead electrocardiography (ECG) and TEE detected new LV regional wall motion abnormalities. Biplane TEE images were recorded on videotape, and LV EDA and ESA were determined with planimetry from images of the LV short axis. Myocardial ischemia was observed in 12 patients. In these patients, EDA and ESA were higher and FAC lower than those patients without ischemia at the same HR. There were no differences between patients with and without myocardial ischemia with regard to pulmonary artery occlusion pressure, stroke volume, or other hemodynamic variables. The positive predictive values were best for ESA (67%) and EDA (58%), and least for FAC (18%). Negative predictive values were highest for ESA (85%) and EDA (80%), and least for FAC (47%). Conclusions: In anesthetized patients undergoing coronary artery bypass surgery, myocardial ischemia observed during atrial pacing results in increases in LV dimensions and decreases in FAC compared with values in patients without ischemia. These results support further investigations of the clinical usefulness of monitoring LV EDA and LV ESA with TEE as a method of myocardial ischemia detection.