Myocardial metabolism during the early phase of urgent coronary surgery and effects of glutamate infusion

• Background. Glutamate has been reported to improve myocardial tolerance to ischemia. As preoperative ischemia remains a major risk factor for myocardial injury in coronary surgery we decided to investigate the impact of intravenous glutamate infusion in patients operated for unstable angina.Methods. 19 patients with unstable angina requiring intravenous nitroglycerine were randomized to intravenous glutamate (30mg/kg (body weight • hour)) or saline. The infusion was started when the patient arrived to the operation theater. Metabolic studies were done just before cardiopulmonary bypass (CPB).Results. The only major substrates that were extracted by the heart in the control group were free fatty acids. In the glutamate group there was also a significant uptake of glutamate and lactate. Furthermore, there was a positive correlation between arterial level and uptake oflactate (r=0.83; p<0.01).Conclusion. The results show an unfavorable metabolic situation for the heart immediately before CPB, which in combination with ischemia could be deleterious. Glutamate infusion was associated with a normal lactate metabolism suggesting that preoperative ischemia was better tolerated.

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MEDICINE

MEDICIN

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