Haemodynamic effects and comparison of enoximone, dobutamine and dopamine following mitral valve surgery

Mitral valve surgery may be complicated by a post-operative low output state requiring inotropic support, and a wide variety of factors may influence the choice of agents used to treat this condition. The authors have examined and compared the haemodynamic effects of the highly specific phosphodiesterase inhibitor enoximone, and the adrenergic agents dobutamine and dopamine in patients undergoing mitral valve surgery. Enoximone, 0.5 mg kg-1 bolus, followed by a continuous infusion of 5 micrograms kg-1 min-1, was compared against dobutamine, 7 micrograms kg-1 min-1, and dopamine, 5 micrograms kg-1 min-1, with the protocol allowing for an increase in the infusion rate by a factor of two if clinical and haemodynamic measurements indicated. All 25 patients receiving enoximone were successfully weaned from cardiopulmonary bypass at the first attempt, with significant increases in cardiac index and stroke index, combined with little or no change in heart rate or pulmonary artery pressures and a highly significant reduction in systemic vascular resistance, and a reduction in mean arterial pressure. Three of the 25 patients receiving dobutamine were withdrawn from the study because of inadequate haemodynamic response, while the remaining 22 patients demonstrated significant increases in heart rate, cardiac index and stroke index, with a reduction in systemic vascular resistance. Nine of the 25 patients receiving dopamine failed to respond adequately, while the remaining 16 demonstrated an increase in heart rate and cardiac index but with little change in stroke index and a modest reduction in systemic vascular resistance. Enoximone has been shown to be a highly effective first-line inotrope in patients following mitral valve surgery with significant advantages over dobutamine and dopamine.