Efficacy of the phosphodiesterase inhibitor enoximone in complicated cardiac surgery.

Acute myocardial dysfunction during cardiac surgery involves various pathophysiologic mechanisms such as reduction in myocardial contractility and an increase in afterload induced by peripheral vasoconstriction. In 30 consecutive patients undergoing coronary artery bypass grafting (CABG) and ten consecutive patients with aortic valve replacement (AVR), in whom therapy with catecholamines was expected to be necessary during and after weaning from cardiopulmonary bypass (CPB) on the basis of a retrospective study ("control" patients), 1.0 mg/kg of the phosphodiesterase (PDE) inhibitor enoximone was administered ten minutes prior to weaning from bypass (enoximone group). In eight CABG and four AVR patients weaning was possible without further pharmacologic support. Significantly less epinephrine was used in enoximone pretreated patients (8.8 +/- 3.0 micrograms/min) than in the control patients (21.4 +/- 4.4 micrograms/kg). The use of additional vasodilators was significantly less pronounced in these patients as well. Seven CABG and four AVR patients in the enoximone group needed additional vasoconstrictors (norepinephrine) to counteract marked, unwanted decrease in peripheral vascular resistance with a decrease in mean arterial pressure (MAP). Hemodynamic monitoring revealed a higher level in heart rate in the control patients with arrhythmia in seven of the CABG patients: MAP, right atrial pressure, cardiac index, and pulmonary capillary wedge pressure were without significant differences between the groups. Pulmonary artery pressure and TSR, however, increased more in the control group, indicating an increase in right and left ventricular afterload. The results of this study demonstrate that patients at risk of circulatory failure during or after weaning from CPB profit from pretreatment with PDE-III inhibitor enoximone due to a reduction in catecholamines and an improvement in hemodynamics.