A Comparison of Prostacyclin and Sodium Nitroprusside for the Treatment of Heart Failure After Cardiac Surgery

Abstract

Comment This well-conducted study demonstrates that prostacyclin may be a useful short-acting vasodilator for afterload reduction in patients with low cardiac output and modest elevations of preload. Compared with nitroglycerin and sodium nitroprusside, prostacyclin appears to have relatively more effect on arterial resistance vessels than on venous capacitance vessels. This is in contrast to nitroglycerin, which primarily affects venous capacitance vessels with limited arterial effect and nitroprusside, which classically reduces both preload and afterload. Therefore, prostacyclin may well be a useful alternative for the patient with low cardiac output and only a modest elevation in wedge pressures. However, prostacyclin is not without its drawbacks. It does induce a dose-dependent and reversible inhibition of platelet aggregation. Under some circumstances, this could be viewed as increasing the risk of bleeding complications. In addition, in this study, prostacyclin increased intrapulmonary shunting more than nitroprusside. This may indicate a greater effect on hypoxic pulmonary vasoconstriction than that found with nitroprusside. However, further study is needed to confirm this, because the prostacyclin group showed a greater increase in cardiac output, and there is a positive correlation between cardiac output and shunt fraction.