[Amrinone (Wincoram)--a new positive inotropic and vasodilator agent]

The bipyridine derivative amrinone is a specific phosphodiesterase III blocking agent. In vitro and in vivo studies show a dose-dependent increase in myocardial contractility induced by amrinone. In patients with congestive heart failure, the inotropic and vasodilator effects of amrinone contribute to cardiac improvement. When amrinone is used, the increase in myocardial oxygen consumption due to increased contractility is offset by the reductions in preload and afterload. In hearts with very high wall tension, myocardial oxygen consumption may even decrease with amrinone. Amrinone therapy is not accompanied by significant increases in heart rate. Tachyphylaxis has not been observed. The elimination half-life ranges between 2.5 and 3.5 h. A large quantity of amrinone is excreted unchanged, and therefore in cases of renal impairment the possibility of cumulation exists. The main adverse reaction of amrinone is a reversible thrombocytopenia induced by a dose-dependent decrease in platelet survival time. Therefore, frequent platelet counts are necessary when amrinone is administered. Numerous studies in patients with chronic congestive heart failure confirmed the beneficial hemodynamic effects of amrinone. Experience in the treatment of acute perioperative heart failure with amrinone are still limited, but the present results are encouraging; an additive effect of amrinone to catecholamines seems especially promising in the therapy of severe postoperative low-cardia-output syndrome.