Extracorporeal circulation for diabetic heart: effects of extracorporeal circulation on cardiac function and myocardial metabolism in canine diabetes
Uga, G.
Nihon Kyobu Geka Gakkai 31(1): 1-12
1983
ISSN/ISBN: 0369-4739 PMID: 6854081 Document Number: 218108
Patients undergoing open-heart surgery are often associated with diabetes mellitus, and thier morbidity and mortality prognosis is poor. There are apparently no reports concerning with the intra- and postoperative pathophysiology of the diabetic heart undergoing open heart surgery. Cardiac performance and myocardial metabolism of the diabetic heart before and after extracorporeal circulation (ECC) were compared with those of the normal heart. Acute diabetes was experimentally produced by i.v. administration of alloxan (90 mg/kg) to dogs. Two days later, aortic cross-clamping was performed for 60 min with mild hypothermia and cold cardioplegia under ECC. Elevated blood glucose level in diabetes decreased after ECC, but remained higher, compared with control. The level in control increased after ECC. Serum insulin level did not significantly change between the pre- and post-ECC values in both groups. In diabetes, heart rate increased and stroke index decreased even before ECC. Systemic blood pressure, left ventricular minute work index and stroke work index in diabetes decreased after ECC. Max (-dp/dt) in diabetes decreased after ECC, but time constant did not alter. Arterio-coronary sinus difference of K ion decreased in both groups after ECC, but the reduction in diabetes was more. Serum lactate and pyruvate levels increased in both groups after ECC, but the elevations in diabetes were more. The lactate extraction ratio in diabetes remained at a low level before and after ECC, being suggestive of the increased anaerobic metabolism in the diabetic heart. Evidently, cardiac performance in diabetes was manifested to be subnormal by cardiopulmonary bypass, and the main cause of the hypofunction was due to poor contractility of the myocardium. The lowering of left ventricular compliance was also not negligible. But it was not conclusive, since the left ventricular volume was not measured in this study. This conclusion implied in practice that cardiopulmonary bypass and postoperative care should be managed carefully because contractility of the myocardium is compromised.