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.