Introduction. Perioperative myocardial injuries are one of the most frequent causes of morbidity and mortality after cardiac surgery, the most common etiology being the poor myocardial protection during aortic crossclamp. During aortic crossclamp progressive accumulation of lactate and intracellular acidosis are well-known phenomena, and are associated with alteration of myocardial contractile function. Our objective was to study the coronary sinus lactate levels as a predictor of postoperative hemodynamic outcome in open-heart surgical patients.
Material and methods. We performed a prospective clinical trial, including 142 adult patients with elective cardiac surgery. Anterograde cardioplegia was administered in 82 patients, retrograde cardioplegia in 60 (in 30 patients it was administrated intermittently and in 30 continuously). Blood was collected simultaneously from the aortic cardioplegic line (inflow) and from coronary sinus or the aortic root (outflow) before aortic crossclamp, after crossclamp at every 10 minutes and after crossclamp removal at 0 and 10 minutes. All patients were operated on cardiopulmonary bypass with cardiac arrest, using warm-blood cardioplegia for cardioprotection.
Results. Lactate levels showed increasing values during aortic crossclamp, and a rapid decline after crossclamp removal. The incidence of low cardiac output was significantly higher in patients with lactate levels that exceeded 4 mmol/L. In patients who died in the postoperative period, lactate level was even higher (5 mmol/L), with only a modest recovery after crossclamp removal.
Conclusion. Monitoring lactate level in coronary sinus blood is a reliable method and has a good prognostic value regarding postoperative morbidity and mortality in open heart surgery