Haemodynamic effects of high doses of insulin during acute left ventricular failure in dogs

Haemodynamic effects of pharmacological doses of insulin during acute ischaemic heart failure were studied in 8 dogs. Severe depression of left ventricular function was induced by the injection of 50 micron plastic microspheres into the left main coronary artery. This was demonstrated by a significant increase in left ventricular end-diastolic pressure and a significant decrease in the maximum rate of left ventricular pressure rise (LVdP/dtmax), stroke volume and cardiac output. Eighty-five minutes after the embolization procedure, 300 IU of insulin free of glucagon and calcium was injected as a bolus. This was followed by infusion of glucose and potassium to maintain physiological levels of these factors. Five minutes after insulin administration, there was a significant improvement in left ventricular performance as shown by decreased left ventricular end-diastolic pressure (P less than 0.01) and increased LVdP/dtmax (P less than 0.01), stroke volume (P less than 0.05) and cardiac output (P less than 0.05). A significant reduction in heart rate occurred. A non-significant increase in mean aortic blood pressure and reduction in total peripheral resistance were seen. In conclusion, pharmacological doses of insulin significantly improve cardiac pump function during acute ischaemic left ventricular failure in dogs.