Myocardial Ischemia During Off-Pump Coronary Artery Bypass Grafting – A Clinical Study

Abstract

Objective: To evaluate relation among trans-esophageal echocardiography (TEE), biochemical and hemodynamic parameters which could possibly help in early detection of myocardial ischemia. Design: Prospective observational, single centre study. Participants: Patients diagnosed with coronary artery triple vessel disease undergoing Off-pump Coronary Artery Bypass Grafting (OPCAB). Results: Statistically significant changes in Coronary Sinus (CS) pH and lactate levels were observed during lateral wall grafting, as well as the highest proportion of new regional wall motion abnormalities observed which signify the presence of a substantial level of myocardial ischemia during this time. We found a significant rise in HR (Heart Rate) as well as CS lactate following lateral wall grafting which correlated with the other parameters indicating substantial ischemia occurring during grafting of that territory. Maximum lactate clearance was found during anterior wall grafting and minimum after inferior wall grafting. This signifies that maximum lactate accumulates after anterior wall grafting, signifying greater extent of myocardial ischemia. Statistically significant rise in (CVP/RAP) (central venous pressure, right atrial pressure was noted) during grafting of all coronary territories, but the maximal rise was seen at the end of lateral wall grafting, followed by grafting of posterior basal wall. Conclusions: Biochemical changes in form of rise in lactate and fall in CS pH doesn’t occur in absence of obvious hemodynamic derangements. Therefore, it is difficult to detect myocardial ischemia before any hemodynamic instability.