Insulin secretion after open-heart surgery with particular respect to pathogenesis of low cardiac output state

Preservation of pancreatic beta cell function with pulsatile cardiopulmonary bypass

Pancreatic islet cell function and tissue metabolism were studied during and after cardiopulmonary bypass in 38 patients undergoing an open heart operation. Twenty patients were operated on with pulsatile cardiopulmonary bypass (group I) and 18, with nonpulsatile cardiopulmonary bypass (group II). Hyperglycemia was observed during and early after operation in both groups. In group I during cardiopulmonary bypass, the immunoreactive insulin and c-peptide levels and the insulin to glucagon molar ratio increased significantly compared with the preoperative values, but in group II, these variables did not alter significantly. An hour postoperatively, the immunoreactive insulin (71 +/- 34 muIU/mL) and c-peptide (8.3 +/- 3.0 ng/mL) levels and the insulin to glucagon molar ratio (11.0 +/- 5.2) in group I were significantly higher than those in group II (immunoreactive insulin, 29 +/- 20 muIU/mL; c-peptide, 4.8 +/- 1.8 ng/mL; insulin to glucagon molar ratio, 3.4 +/- 2.6). The blood lactate level in group I (41 +/- 22 mg/dL) was significantly lower than that in group II (78 +/- 30 mg/dL) an hour postoperatively. In conclusion, pulsatile cardiopulmonary bypass is quite effective in preserving pancreatic beta cell function and tissue metabolism during and early after open heart procedures.

Metabolic effect of glucose, insulin and potassium cardioplegia

Glucose-insulin-potassium (GIK) solution is widely used as a cardioplegic infusate for myocardial protection during aortic cross-clamping, to obtain rapid diastolic arrest and preservation of energy stores. Nine male patients with aorto-coronary bypass grafting procedure were studied with regard to the metabolic influence of GIK cardioplegia. Hyperglycemia was induced by the infusion of GIK solution for one week after surgery. The serum level of non-esterified fatty acid was high for one week while the triglyceride level was maintained at a high level only in the early post-operative period. Insulin, glucagon and growth hormone which influence carbohydrate and lipid metabolism were also elevated for one week after infusion of GIK solution. We conclude that the derangement of carbohydrate and lipid metabolism which is provoked by the use of GIK cardioplegia normalizes within two weeks after operation.

Rheological and biochemical changes in open heart surgery with extracorporeal circulation and moderate hypothermia

The plasma enzymes, glucose, urea nitrogen, total and conjugated bilirubin, osmolality, acid--base balance and rheological data have been studied in a group of patients who underwent open heart surgery to replace the stenotic or insufficient aortic valve. The aim of this study was to assess our operative conditions and to compare results with those obtained by other authors.

Insulin therapy for depressed myocardial contractility after prolonged ischemia

Insulin was administered to two patients whose diminished myocardial contractility made it difficult to terminate cardiopulmonary bypass. In both instances, bypass was successfully terminated shortly after the insulin injection. These clinical observations led to experiments under the controlled conditions provided by the isolated, working rat heart preparation. The recovery of contractility after 30 minutes of severe ischemia was assessed in all 11 control and 11 insulin-treated hearts. Myocardial performance, as judged by the product of heart rate and peak systolic blood pressure, was significantly greater in the insulin-treated hearts. These clinical observations and experimental findings suggest the need for more extensive study of the potential value of insulin in treating depressed contractility after prolonged myocardial ischemia.

Can the frequency of myocardial infarction be reduced during coronary artery operations

A prospective experiment was carried out in 56 patients undergoing coronary artery revascularization to determine whether those having a glucose-insulin-potassium (GIK) perfusion during the procedure would have fewer myocardial infarctions (MI) compared with patients given a control perfusion of Normosol-R. Six patients (11%) developed an MI, defined as a 24-hour creatine phosphokinase MB isoenzyme value of 100 IU per liter or greater. Four (13%) had control perfusions and 2(8%) had GIK perfusion. One MI in a double-graft recipient who had GIK perfusion occurred because of a technical surgical error; therefore, the corrected MI rate was 13% in control patients compared with 4% for the GIK group. These data, as well as the more frequent spontaneous defibrillation in patients who had GIK perfusion, suggest that GIK was of benefit.

Postoperative arrhythmias in open-heart surgery, A study on fifty cases

50 consecutive patients undergone open heart surgery were analyzed regarding postoperative arrhythmias in the first postoperative 3 days. Disturbances of rhythm occurred in each case of our group, serious or not serious (100%). Ventricular premature beats were the most frequent type of arrhythmia in the first and second postoperative days (80%). Two cases expired postoperatively. In one of them complete atrioventricular block developed after double valvular replacements (mitral and tricuspid). The other died of low cardiac output syndrome. Etiology of the arrhythmias after open heart surgery is not clear in the absence of electrolyte and metabolic disturbances, digitalis intoxication and surgical trauma to the conduction system and coronary arteries. Low cardiac output syndrome, hypotension and hypoxia can also be blamed in the formation of these arrhythmias. Other factors such as the prolongation of anoxic arrest, irritation of the ventricular septum by valvular prostheses, cardiac irritation by thoracic tubes, psychologic trauma, halothane anesthesia and coronary arterial disease in the old age group may be the possible predisposing factors in these patients.

Metabolic changes in surface-induced deep hypothermia combined with cardiopulmonary bypass for cardiac surgery

Surface induced deep hypothermia combined with cardiopulmonary bypass (combined method) is excellent in open heart surgery of infants which combines each advantage of cardiopulmonary bypass and hypothermia. The present study was performed to investigate pathophysiological changes, especially metabolic changes, in combined method induced by two stressors such as cardiopulmonary bypass and hypothermia. In general, metabolic changes during hypothermia are temporarily enhanced immediately after the start of cardiopulmonary bypass. Lactacidemia and metabolic acidosis are rapidly improved after the start of perfusion rewarming, but abnormality of ceruloplasmin and cholesterol metabolism in the liver and hypopotassemia are not rapidly improved. Therefore, the treatment for these metabolic abnormalities seems to be necessary during and after the procedure.