Successful Use of Levosimendan in a Patient During Cardiopulmonary Bypass

Use of levosimendan in patients with ischemic heart disease following mechanical reperfusion

Cardiac failure is among the most significant conditions associated with acute coronary syndrome. In ischemic heart disease, serious hemodynamic problems are reported in patients with left ventricular dysfunction during the acute phase despite mechanical revascularization. Several positive inotropic agents in addition to intra-aortic balloon pump (IABP) are required to support patients with impaired left ventricular pump function during this phase. Intravenous inotropic agents, beta-mimetics, and phosphodiesterase inhibitors lead to increases in the incidence of arrhythmia and myocardial O(2) consumption owing to their effect of increasing intracellular calcium amount, although they produce rapid hemodynamic improvements in cardiac failure. This causes severe problems particularly in cardiac failure of ischemic origin. Recently, levosimendan, a calcium-sensitizing agent with cardioprotective properties, is being used alone or in combination with IABP in cases with severe left ventricular systolic dysfunction during mechanical revascularization procedures (percutaneous coronary interventions, coronary bypass surgery). This review includes studies with levosimendan in cases not recovering due to myocardial stunning in the acute phase despite mechanical approaches applied.

Levosimendan facilitates weaning from cardiopulmonary bypass in patients undergoing coronary artery bypass grafting with impaired left ventricular function

BACKGROUND

Levosimendan is a compound with vasodilatory and inotropic properties. Experimental data suggest effective reversal of stunning and cardioprotective properties.

METHODS

This prospective, randomized, placebo-controlled, double-blind study included 60 patients with 3-vessel coronary disease and left ventricular ejection fraction (LVEF) of less than 0.50. Levosimendan administration (12 microg/kg bolus, followed by an infusion of 0.2 microg/kg/min) was started immediately after induction anesthesia. Predefined strict hemodynamic criteria were used to assess the success of weaning. If weaning was not successful, CPB was reinstituted and an epinephrine infusion was started. If the second weaning attempt failed, intraaortic balloon pumping (IABP) was instituted.

RESULTS

The groups had comparable demographics. The mean (standard deviation) preoperative LVEF was 0.36 (0.8) in both groups. The baseline cardiac index was 1.8 (0.3) L/min/m(2) in the levosimendan group and 1.9 (0.4) L/min/m(2) in the placebo group. The mean duration of CPB to primary weaning attempt was 104 (25) minutes in the levosimendan and 109 (22) minutes in the placebo group. Primary weaning was successful in 22 patients (73%) in the levosimendan group and in 10 (33%) in the placebo group (p = 0.002). The odds ratio for failure in primary weaning was 0.182 (95% confidence interval, 0.060 to 0.552). Four patients in the placebo group failed the second weaning and underwent IABP compared with none in the levosimendan group (p = 0.112).

CONCLUSIONS

Levosimendan significantly enhanced primary weaning from CPB compared with placebo in patients undergoing 3-vessel on-pump coronary artery bypass grafting. The need for additional inotropic or mechanical therapy was decreased.

Clinical pharmacology of levosimendan

Levosimendan has been developed for the treatment of decompensated heart failure and is used intravenously when patients with heart failure require immediate initiation of drug therapy. It increases cardiac contractility and induces vasodilatation. The pharmacokinetics of levosimendan are linear at the therapeutic dose range of 0.05-0.2 microg/kg/minute. The short half-life (about 1 hour) of the parent drug, levosimendan, enables fast onset of drug action, although the effects are long-lasting due to the active metabolite OR-1896, which has an elimination half-life of 70-80 hours in patients with heart failure (New York Heart Association functional class III-IV). Although levosimendan is administered intravenously, it is excreted into the small intestine and reduced by intestinal bacteria to an amino phenolpyridazinone metabolite (OR-1855). This metabolite is further metabolised by acetylation to N-acetylated conjugate (OR-1896). The circulating metabolites OR-1855 and OR-1896 are formed slowly, and their maximum concentrations are seen on average 2 days after stopping a 24-hour infusion. The haemodynamic effects after levosimendan seem to be similar between fast and slow acetylators despite the fact that the enzyme N-acetyltransferase-2, which is responsible for the metabolism of OR-1855 to OR-1896, is polymorphically distributed in the population. Levosimendan reduces peripheral vascular resistance and has direct contractility-enhancing effects on the failing left ventricle. It also improves indices of diastolic function and seems to improve the function of stunned myocardium. Despite an improvement in ventricular function, levosimendan does not increase myocardial oxygen uptake significantly. An increase in coronary blood flow and a reduction in coronary vascular resistance have been observed. Levosimendan reduces plasma brain natriuretic peptide (BNP) and N-terminal pro-BNP (NT-proBNP) levels substantially, and a decrease in plasma endothelin-1 has been observed. Levosimendan also exerts beneficial effects on proinflammatory cytokines and apoptosis mediators. The effects of a 24-hour levosimendan infusion on filling pressure, ventricular function and BNP, as well as NT-proBNP, last for at least 7 days.