Levosimendan Treatment After Primary Organ Failure in Heart Transplantation: A Direct Way to Recovery?

Levosimendan as rescue therapy in low output syndrome after cardiac surgery: effects and predictors of outcome

Objectives

Calcium sensitizers have been shown to improve outcomes in patients with low cardiac output syndrome (LCOS) after cardiac surgery. We assessed the effects of levosimendan on LCOS in cardiac surgical patients to identify outcome predictors.

Methods

A total of 106 patients in whom LCOS persisted despite conventional therapy additionally received 0.1 µg/kg/min of levosimendan for 24 hours according to a defined treatment algorithm. Baseline and treatment data as well as hemodynamic and outcome parameters were compared between survivors and nonsurvivors, and a multivariate correlation and regression tree analysis was implemented.

Results

The ejection fraction significantly increased from 27% ± 4% to 38% ± 8% within 24 hours and to 45% ± 10% within 48 hours of starting levosimendan. These changes were accompanied by a significant increase in cardiac output from 5.2 ± 0.6 to 6.2 ± 0.7 L/min within 24 hours and significant dose reductions in vasopressors and inotropes. In contrast to nonsurvivors, survivors’ need for inotropic support decreased after the addition of levosimendan to the therapy.

Conclusion

In our patients, all of whom were treated according to the same algorithm, the response to levosimendan in terms of the post-levosimendan need for inotropes and vasopressors predicted survival.

Levosimendan protects human hepatocytes from ischemia-reperfusion injury

Background

Ischemia-reperfusion injury (IRI) is a major challenge in liver transplantation. The mitochondrial pathway plays a pivotal role in hepatic IRI. Levosimendan, a calcium channel sensitizer, was shown to attenuate apoptosis after IRI in animal livers. The aim of this study was to investigate the effect of levosimendan on apoptosis in human hepatocytes.

Methods

Primary human hepatocytes were either exposed to hypoxia or cultured under normoxic conditions. After the hypoxic phase, reoxygenation was implemented and cells were treated with different concentrations of levosimendan (10ng/ml, 100ng/ml, 1000ng/ml). The overall metabolic activity of the cells was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and aspartate aminotransferase (AST) levels were determined in order to quantify hepatic injury. Fluorescence-activated cell sorting (FACS) analysis was applied to measure necrosis and apoptosis. Finally, Western blotting was performed to analyze apoptotic pathway proteins.

Results

Administration of levosimendan during reperfusion increases the metabolic activity of human hepatocytes and decreases AST levels. Moreover, apoptosis after IRI is reduced in treated vs. untreated hepatocytes, and levosimendan prevents down-regulation of the anti-apoptotic protein Bcl-2 as well as up-regulation of the pro-apoptotic protein BAX.

Conclusion

The present study suggests a protective effect of levosimendan on human hepatocytes. Our findings suggest that treatment with levosimendan during reperfusion attenuates apoptosis of human hepatocytes by influencing BAX and Bcl-2 levels.

Levosimendan reverses right-heart failure in a 51-year-old patient after heart transplantation

Primary graft failure in the early postoperative period after heart transplantation, remains a main cause of a poor outcome. Current treatment options include pharmacological (catecholamines and phosphodiesterase inhibitors) and mechanical assist device support. Pharmacological support with catecholamines is related to elevated myocardial oxygen consumption and regional hypoperfusion leading to organ damage. On the other hand, levosimendan, as a calcium-sensitizing agent increases cardiac contractility without altering intracellular Ca(2+) levels and increase in oxygen demand. We present a case of a 51-year-old man, who was suffering from acute right-heart failure in the early postoperative period after heart transplantation. As a rescue therapy at the late stage of a low cardiac output state, levosimendan was started as continuous infusion at 0.1 μg/kg/min for 12 h and thereafter, at 0.2 μg/kg/min for the following 36 h. Levosimendan demonstrated an advanced pharmacological option as was portrayed in this case, where the right ventricle was under a prolonged severe depression and acutely overloaded after heart transplantation.

Primary graft failure after heart transplantation

Primary graft failure (PGF) is a devastating complication that occurs in the immediate postoperative period following heart transplantation. It manifests as severe ventricular dysfunction of the donor graft and carries significant mortality and morbidity. In the last decade, advances in pharmacological treatment and mechanical circulatory support have improved the outlook for heart transplant recipients who develop this complication. Despite these advances in treatment, PGF is still the leading cause of death in the first 30 days after transplantation. In today's climate of significant organ shortages and growing waiting lists, transplant units worldwide have increasingly utilised "marginal donors" to try and bridge the gap between "supply and demand." One of the costs of this strategy has been an increased incidence of PGF. As the threat of PGF increases, the challenges of predicting and preventing its occurrence, as well as the identification of more effective treatment modalities, are vital areas of active research and development.

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.