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

Objective: Because of adverse effects of cardiopulmonary bypass and the pro spect of shortening intensive care and hospital stay, coronary artery bypas s grafting without cardiopulmonary bypass is gaining increased attention. T he impact of the localized myocardial ischemia that is inherent in these pr ocedures has not been thoroughly investigated in human beings. We have inve stigated metabolic changes, possible myocardial damage, and myocardial outf low of the vasodilator calcitonin gene-related peptide during coronary arte ry bypass grafting without cardiopulmonary bypass, Methods: Coronary sinus and arterial blood was sampled before coronary arterial occlusion, after 10 minutes of ischemia, and after 1 and 10 minutes of reperfusion in 9 consec utive patients (mean age 70 +/- 5 years) who had an anastomosis performed t o the left anterior descending artery without cardiopulmonary bypass. Resul ts: No perioperative myocardial infarctions occurred. The arteriovenous dif ference in lactate decreased during ischemia, to reach a minimum after 1 mi nute of reperfusion (-0.17 +/- 0.25 vs 0.15 +/- 0.25 mmol/L before ischemia ; P =.008). Myocardial lactate extraction decreased (from 11.2 +/- 13.6 mu mol/min before ischemia to 3.0 +/- 7.0 mu mol/min after 1 minute of reperfu sion; P =.012), that is, a net production of lactate. The arteriovenous dif ference in calcitonin gene-related peptide decreased from -0.1 +/- 2.6 pmol /L before ischemia to 30.5 +/- 26.5 pmol/L (P =.008) after 1 minute of repe rfusion, Conclusions: The localized myocardial ischemia associated with the se procedures causes metabolic changes in the myocardium, but no myocardial damage, The ischemia-related outflow of calcitonin gene-related peptide in dicates that the vasodilating and cardioprotective properties of this pepti de that are known from animal studies may be of importance in myocardial is chemia in human beings.