Effects of glucagon on left ventricular function in man with controlled heart rate. Use of ball travel time as an indicator of myocardial contractility.

Abstract

Five patients with aortic Starr-Edwards valves were studied during routine postoperative catheterization. The hemodynamic effects of 5 mg of intra venous glucagon were measured with and without atrial pacing to control the heart rate. Left ventricular function was assessed, using mean systolic ejection rate and the time taken for the ball of the prosthesis to cross the cage (ball travel time), which is closely related to maximum acceleration of blood into the ascending aorta. Heart rate rose by 22% and cardiac output by 14% when the atrium was not paced. With heart rate controlled, there was no significant change in cardiac output, mean systolic ejection rate or in ball travel time. A slight reduction in atrioventricular conduction time was observed. It is suggested that glucagon has no positive inotropic action in man independent of heart rate in these experimental conditions.