Detection of intraoperatiye myocardial ischaemia — a comparison among electrocardiographic, myocardial metabolic, and haemodynamic measurements in patients with reduced ventricular function

Abstract

Detection CAN J ANAESTH 1995 / 42:6 / pp487-94

Myocardial outflow of calcitonin gene-related peptide in relation to metabolic stress during coronary artery bypass grafting without cardiopulmonary bypass

“…In this context, ST-segment changes in the ECG are of very limited value, particularly because of low sensitivity. 7 The absence of STsegment changes in the present study thus has little bearing on the assessment of ischemia.…”

“…The heart normally extracts lactate as a part of aerobic metabolism. 21 Although myocardial lactate production is considered to be a good indicator of myocardial ischemia, 7 it should be kept in mind that coronary sinus lactate levels only vaguely reflect the substantially elevated lactate levels in ischemic tissue. 6 Thus the present finding of myocardial lactate production during and early after ischemia most likely represents true myocardial ischemia.…”

“…In experimental ischemia in the pig, a 300% increase in tissue lactate was observed within 15 minutes, 6 and lactate production is widely used as an indicator of anaerobic metabolism. 7 In clinical situations such as conventional CABG, 8 unstable angina, 9 and radiofrequency catheter ablation, 10 troponin T has proved to be a highly sensitive and specific tool in evaluating even minor myocardial damage, C oronary artery bypass grafting (CABG) is routinely performed with cardiopulmonary bypass (CPB), with excellent results. However, CPB has been associated with several adverse effects, 1,2 and CABG without Objective: Because of adverse effects of cardiopulmonary bypass and the prospect of shortening intensive care and hospital stay, coronary artery bypass grafting without cardiopulmonary bypass is gaining increased attention.…”

Release and effects of calcitonin gene-related peptide in myocardial ischaemia

“…This results in increased lactate production, which is considered to be a definite indicator of myocardial ischaemia (Hall et al, 1995). Wikström et al determined a 300% increase in tissue lactate, and a 50% decrease in pyruvate after 15 minutes occlusion of a coronary artery (Wikström et al, 1995).…”

“…We determined that the relatively short-lasting coronary occlusion that is associated with CABG off bypass induces adjustments in lactate metabolism. Myocardial lactate production is considered to be a good indicator of myocardial ischaemia (see Hall et al, 1995), but it should be kept in mind that coronary sinus lactate levels only vaguely reflect the substantially elevated lactate levels in ischaemic tissue (Wikström et al, 1995). Therefore, the present finding of myocardial lactate production during and early after ischaemia most likely represents true myocardial ischaemia, although there were no perioperative myocardial infarctions as assessed by enzyme or ECG criteria.…”