Beneficial haemodynamic effects of insulin in chronic heart failure.

Objective: To characterise the central and regional haemodynamic effects of insulin in patients with chronic heart failure.

Design: Single blind, placebo controlled study.

Setting: University teaching hospital.

Patients: Ten patients with stable chronic heart failure.

Interventions: Hyperinsulinaemic euglycaemic clamp and non-invasive haemodynamic measurements.

Main Outcome Measures: Change in resting heart rate, blood pressure, cardiac output, and regional splanchnic and skeletal muscle blood flow.

Results: Insulin infusion led to a dose dependent increase in skeletal muscle blood flow of 0.36 (0.13) and 0.73 (0.14) ml/dl/min during low and high dose insulin infusions (p < 0.05 and p < 0.005 v placebo, respectively). Low and high dose insulin infusions led to a fall in heart rate of 4.6 (1.4) and 5.1 (1.3) beats/min (p < 0.05 and p < 0.005 v placebo, respectively) and a modest increase in cardiac output. There was no significant change in superior mesenteric artery blood flow.

Conclusion: In patients with chronic heart failure insulin is a selective skeletal muscle vasodilator that leads to increased muscle perfusion primarily through redistribution of regional blood flow rather than by increased cardiac output. These results provide a rational haemodynamic explanation for the apparent beneficial effects of insulin infusion in the setting of heart failure.