[Metabolic myocardial modifications following surgical revascularization]

The effects of aorto-coronary bypass surgery on myocardial lactate, free fatty acid and certain amino acid metabolism were studied in 30 coronary patients presenting with unstable, invalidating angina resistant to medical therapy. These patients had electrical signs of anterior wall ischemia without necrosis, significant proximal stenosis of the left anterior descending artery with good distal run-off, and underwent bypass surgery on this artery without signs of postoperative myocardial infarction. This study involved pre- and postoperative hemodynamic investigation with a Swan-Ganz catheter and a metabolic study of the coronary arteriovenous lactate (n = 30), free fatty acid, alanine and glutamate (n = 12) levels under basal conditions and after atrial pacing. These results were compared with those in 10 non-coronary control patients, operated for monovascular replacements. The increase of the pulmonary capillary pressure associated with a fall in systolic index at the 6th postoperative hour showed a reduction in left ventricular performance which tended to correct itself at the 24th hour. In the coronary patients, myocardial lactate production increased, alanine production increased and the uptake of free fatty acids fell during atrial pacing after surgery. These metabolic changes reflect the stimulation of anaerobic glycolysis secondary to myocardial ischemia which disappeared after surgery to compare with the control subjects. Therefore, effective myocardial revascularisation in patients with coronary artery disease is accompanied by the regression of the metabolic stigmata of myocardial ischemia.