Effect of Drugs on Effective Vascular Compliance in Acute Heart Failure

Effective vascular compliance determined by the delta V/delta P relationship was measured repeatedly in anesthetized open-chest dogs without circulatory arrest utilizing a closed circuit venous bypass system with a constant cardiac output. Production of acute heart failure by gradual aortic constriction was associated with a significant decrease in total effective vascular compliance. The effect of loading and 20-min maintenance doses of different drugs on vascular compliance of animals in acute heart failure was studied. Phenoxybenzamine (total dose 2 mg/kg) produced a rapid and sustained increase in effective vascular compliance and theophylline (12 mg/kg) produced an increase which was more gradual in development than with phenoxybenzamine. Morphine (1 mg/kg) produced a rapid but transient increase in compliance. In contrast, ethacrynic acid (100 mg) or nitroglycerin (0.6 or 1.2 mg) did not alter vascular compliance significantly. These agents differ markedly in the magnitude and time-course of effect on effective vascular compliance.