Potential mechanisms of improved left ventricular function with enoximone in severe congestive heart failure

Enoximone, a phosphodiesterase inhibitor, is a potent inotropic vasodilator agent that causes a marked improvement in systemic hemodynamics in patients with severe chronic congestive heart failure. Cardiac index, stroke volume index and stroke work index increase, and there is a significant decrease in pulmonary capillary wedge pressure. Left ventricular dP/dt increases, despite a decrease in arterial pressure and systemic vascular resistance and without any significant change in heart rate, indicating a positive inotropic effect. A marked decrease in systemic vascular resistance indicates that decreased left ventricular outflow resistance resulting from peripheral vasodilation also contributes to improvement in left ventricular function. In some patients, left ventricular end-diastolic volume increases despite a marked decrease in pulmonary capillary wedge pressure, suggesting an improvement in apparent left ventricular compliance, which may also be contributory to improved left ventricular function.