Current medical treatment for the exacerbation of chronic heart failure resulting in hospitalization.
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Compounds that sensitize cardiac muscle to Ca(2+) by intervening at the level of regulatory thin filament proteins would have potential therapeutic benefit in the treatment of myocardial infarctions. Two putative Ca(2+) sensitizers, EMD 57033 and levosimendan, are reported to bind to cardiac troponin C (cTnC). In this study, we use heteronuclear NMR techniques to study drug binding to [methyl-(13)C]methionine-labeled cTnC when free or when complexed with cardiac troponin I (cTnI). In the absence of Ca(2+), neither drug interacted with cTnC. In the presence of Ca(2+), one molecule of EMD 57033 bound specifically to the C-terminal domain of free cTnC. NMR and equilibrium dialysis failed to demonstrate binding of levosimendan to free cTnC, and the presence of levosimendan had no apparent effect on the Ca(2+) binding affinity of cTnC. Changes in the N-terminal methionine methyl chemical shifts in cTnC upon association with cTnI suggest that cTnI associates with the A-B helical interface and the N terminus of the central helix in cTnC. NMR experiments failed to show evidence of binding of levosimendan to the cTnC.cTnI complex. However, levosimendan covalently bound to a small percentage of free cTnC after prolonged incubation with the protein. These findings suggest that levosimendan exerts its positive inotropic effect by mechanisms that do not involve binding to cTnC.
Levosimendan is an inodilatory drug that mediates its cardiac effect by the calcium sensitization of contractile proteins. The target protein of levosimendan is cardiac troponin C (cTnC). In the current work, we have studied the interaction of levosimendan with Ca(2+)-saturated cTnC by heteronuclear NMR and small angle x-ray scattering. A specific interaction between levosimendan and the Ca(2+)-loaded regulatory domain of recombinant cTnC(C35S) was observed. The changes in the NMR spectra of the N-domain of full-length cTnC(C35S), due to the binding of levosimendan to the primary site, were indicative of a slow conformational exchange. In contrast, no binding of levosimendan to the regulatory domain of cTnC(A-Cys), where all the cysteine residues are mutated to serine, was detected. Moreover, it was shown that levosimendan was in fast exchange on the NMR time scale with a secondary binding site in the C-domain of both cTnC(C35S) and cTnC(A-Cys). The small angle x-ray scattering experiments confirm the binding of levosimendan to Ca(2+)-saturated cTnC but show no domain-domain closure. The experiments were run in the absence of the reducing agent dithiothreitol and the preservative sodium azide (NaN(3)), since we found that levosimendan reacts with these chemicals, commonly used for preparation of NMR protein samples.
BACKGROUND: Levosimendan is a calcium sensitizer that increases the contractility of the myofilaments and is considered not to affect cardiac electrophysiology. We assessed its potential to generate cardiac arrhythmias by analysing ECG recordings from clinical studies on intravenously administered levosimendan in heart failure patients. METHODS AND RESULTS: The database consisted of continuous 1-day recordings, of which 366 were during levosimendan and 142 during placebo comparison. Supraventricular (SVT) and ventricular tachycardia (VT) were defined as > or =3 premature complexes at a rate > or = 120/min. No difference appeared between levosimendan and control groups in the occurrence of atrial fibrillation (12% vs 13%), SVT (28% vs 30%), or VT (41% vs 44% of all recordings; all p = NS). Also the frequency of VT was similar (0.55 +/- 3.89 vs 0.20 +/- 1.08 episodes/h; p = NS). No torsade de pointes or sustained VT occurred. CONCLUSION: Short-term levosimendan therapy of heart failure showed no tendency to increase cardiac arrhythmias. Although assessing only surrogates of prognostically significant arrhythmias, the findings together with previously observed reduction of mortality in heart failure therapy studies support the presumption that levosimendan has an electrophysiologically neutral profile.
Levosimendan, a calcium sensitizer, was used in combination with beta-adrenergic antagonists in a man aged 56 yr with cardiogenic shock, complicating acute myocardial infarction, who developed severe tachycardia after dobutamine administration. The patient's trachea was intubated, his lungs were ventilated, and he was started on dopamine 5 microg kg(-1) min(-1) and dobutamine 5 microg kg(-1) min(-1), titrated to a mean arterial pressure > or =65 mm Hg. He progressively became tachycardiac (>120 beats min(-1)) with a cardiac index (CI) of 1.4 litre min(-1) m(-2) despite adequate preload. Levosimendan 6 microg kg(-1) was administered intravenously over 10 min followed by a continuous infusion of 0.2 microg kg(-1) min(-1) for 24 h. Within 30 min, the patient's CI increased to 2.2 litre min(-1) m(-2), but the heart rate (HR) also increased from 142 to 155 beats min(-1). Esmolol 1 mg kg(-1) i.v. was administered with a consequent transient decrease in HR to 110 beats min(-1) without adverse haemodynamic effects; however, HR increased again shortly afterwards. Carvedilol 3.125 mg orally twice a day was then administered, and the dose was increased to 6.25 mg orally twice daily on the following day. Subsequently, HR decreased over time and both catecholamines were discontinued 14 h after starting levosimendan infusion. The trachea was extubated within 20 h and the patient was discharged to the ward on day 4 after admission. In conclusion, levosimendan in combination with a beta-adrenergic antagonist may have beneficial effects in patients with cardiogenic shock who exhibit tachycardia in response to inotropic agents.
BACKGROUND: The calcium sensitizer levosimendan protects against myocardial ischaemia and reperfusion injury in animal models. METHODS: The present pilot study investigated whether a short infusion before coronary artery bypass grafting (CABG) would protect the myocardium and improve postoperative haemodynamics. Twenty-four patients with stable angina undergoing elective CABG surgery were randomized to receive either placebo or levosimendan (24 microg kg(-1)) infused i.v. over a 10 min period just before placing the patient on cardiopulmonary bypass. RESULTS: Perioperative haemodynamic variables, concentrations of cardiac troponin I over the 48 h postoperative period, and clinical outcomes were assessed. There were no adverse effects related to levosimendan. Compared with control patients, levosimendan-treated patients had lower postoperative troponin I concentrations (P<0.05) and a higher cardiac index (P<0.05). CONCLUSION: Patients receiving a short infusion of levosimendan before CABG showed evidence of less myocardial damage, suggestive of a preconditioning effect. Larger outcome studies are thus indicated to confirm benefit.
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Levosimendan is a new calcium sensitizer and K-ATP channel opener. Compared with other inodilators, it improves myocardial contractility without increasing oxygen requirements and induces peripheral and coronary vasodilation with a potential anti-stunning, anti-ischaemic effect. The documentation regarding levosimendan is one of the largest ever on the safety and efficacy of a new pharmacological agent in acute heart failure syndromes. Recent experiences in small-scale studies and randomized clinical trials have led to greater interest in the use of this drug for the support of impaired cardiac function also in patients with ischaemic heart disease and cardiogenic or septic shock. It is also demonstrated that this drug could be used as bridge therapy for the peri-operative phase of cardiac surgery in both adult and paediatric populations. This review summarizes the evidence from published scientific literature regarding the use of levosimendan in various clinical settings.
A decrease in myofilament sensitivity to Ca2+ has been proposed as a mechanism for reversible contractile dysfunction after ischemia and reperfusion. The direct actions of intracoronary myofilament Ca2+ sensitizers on stunned myocardium have not been examined. Barbiturate-anesthetized dogs (n = 9) were instrumented for measurement of left ventricular (LV) and aortic blood pressure, cardiac output, left anterior descending coronary artery (LAD) blood flow velocity, and subendocardial segment length (percent segment shortening [%SS]). Dogs were subjected to five 5-min LAD occlusions interspersed by 5-min reperfusions. Three hours after the final reperfusion, levosimendan (1.5, 3, 6, and 12 microg/min) was administered via an intracoronary catheter. Hemodynamic effects and regional myocardial function were determined under control conditions, during each LAD occlusion and reperfusion, 3 h after final reperfusion, and after 10 min equilibration at each dose of levosimendan. Three hours after the final reperfusion, %SS and the ratio of effective to total regional work were significantly (P < 0.05) decreased, and postsystolic shortening area was increased, consistent with myocardial stunning. In stunned myocardium, intracoronary levosimendan caused dose-dependent increases in %SS (2 +/- 1 at 3 h after reperfusion to 13% +/- 2% during 12 microg/min), abolished postsystolic shortening area, and restored the ratio of effective to total regional work while producing minimum systemic hemodynamic effects.
UNLABELLED: We tested the hypothesis that levosimendan, a new positive inotropic drug that activates adenosine triphosphate-regulated potassium (K(ATP)) channels in vitro, decreases myocardial infarct size in vivo. Myocardial infarct size was measured after a 60-min left anterior descending coronary artery occlusion and 3 h of reperfusion in dogs receiving either IV vehicle (0.9% saline) or levosimendan (24 microg/kg bolus followed by an infusion of 0.4 microg x kg(-1) x min(-1)) in the presence or absence of glyburide (a K(ATP) channel antagonist) pretreatment (100 microg/kg). Levosimendan increased (P < 0.05) the maximal rate of increase of left ventricular pressure and decreased myocardial infarct size from 24%+/-2% (control experiments) to 11%+/-2% of the left ventricular area at risk for infarction. Glyburide did not alter the hemodynamic effects of levosimendan but blocked levosimendan-induced reductions of infarct size. Subendocardial collateral blood flow was similar among groups. However, levosimendan increased subepicardial and midmyocardial collateral perfusion in the absence, but not in the presence, of glyburide. Levosimendan exerts cardioprotective effects via activation of K(ATP) channels at a dose that simultaneously enhances myocardial contractility. IMPLICATIONS: Levosimendan may be advantageous in patients requiring inotropic support who are also at risk of myocardial ischemia. Activation of adenosine triphosphate-regulated potassium channels during infusion of levosimendan may produce cardioprotective effects while simultaneously enhancing ventricular contractile function.
UNLABELLED: Calcium-sensitizing drugs, such as levosimendan, are a novel class of drug therapy for heart failure. We investigated the hypothesis that levosimendan is a pulmonary vasodepressor mediated through inhibition of phosphodiesterase, adenosine triphosphate (ATP)-dependent potassium channels, or both. We investigated responses to the calcium sensitizer levosimendan in the pulmonary vascular bed of the cat under conditions of controlled pulmonary blood flow and constant left atrial pressure when lobar arterial pressure was increased to a high steady level with the thromboxane A(2) analog U-46619. Under increased-tone conditions, levosimendan caused dose-related decreases in lobar arterial pressure without altering systemic arterial and left atrial pressure. Responses to levosimendan were significantly attenuated, although not completely, after the administration of U-37883A, a vascular selective nonsulfonylurea ATP-sensitive K(+)-channel-blocking drug. Responses to levosimendan were not significantly different after the administration of the nitric oxide synthase inhibitor L-N(5)-(1-iminoethyl)-ornithine or the cyclooxygenase inhibitor sodium meclofenamate or when lung ventilation was interrupted. These data show that levosimendan has significant vasodilator activity in the pulmonary vascular bed of the cat. They also suggest that pulmonary vasodilator responses to levosimendan are partially dependent on activation of ATP-sensitive K(+) channels and independent of the synthesis of nitric oxide, activation of cyclooxygenase enzyme, or changes in bronchomotor tone in the pulmonary vascular bed of the cat. IMPLICATIONS: Calcium-sensitizing drugs, such as levosimendan, are a novel class of drug therapy for heart-failure treatment. The lung circulation affects both right- and left-sided heart failure. Levosimendan decreased lobar arterial pressure via a partial K(+)(ATP) (potassium channel sensitive to intracellular adenosine triphosphate levels)-dependent mechanism. These data suggest that, in addition to calcium-sensitizing activity, levosimendan decreases pulmonary resistance, which may also aid in the treatment of heart failure.
BACKGROUND: Because sepsis-induced myocardial dysfunction related to sepsis is at least partially related to a decrease in cardiac myofilament response to calcium, the use of the new myofilament-calcium sensitizer, levosimendan, has been proposed. In addition, arginine vasopressin is increasingly proposed as a vasopressor in septic patients, although data on its effects on cardiac function are still scarce. The aim of the current study was to assess, invasively and noninvasively, whether levosimendan, arginine vasopressin, and norepinephrine, either alone or combined, may modify sepsis-induced myocardial dysfunction and renal hemodynamics. METHODS: Thirty-six hours after lipopolysaccharide or saline administration, rabbits were studied either after slight sedation for echocardiography or after general anesthesia with sodium pentobarbital for the following measurements: aortic flow velocity and maximum acceleration of blood flow in the ascending aorta and renal macrocirculation and microcirculation. RESULTS: Levosimendan improved, within 30 min of administration, both maximum acceleration of blood flow by 20 +/- 12% (n = 8; P < 0.05) and left ventricular shortening fraction by a similar extent. Furthermore, low doses of arginine vasopressin markedly deteriorated cardiac function via an afterload-independent mechanism, even when animals were pretreated with levosimendan, whereas norepinephrine showed no detrimental effects on cardiac function. The study also showed that norepinephrine often improved renal medullary blood flow, whereas arginine vasopressin consistently decreased it. CONCLUSION: Levosimendan and norepinephrine both exert beneficial effects in endotoxemic animals and should be further explored in human sepsis trials.
Several clinical studies suggest substantial limitations of currently available positive inotropic substances, including beta1-adrenoceptor agonists and phosphodiesterase III inhibitors in the short- and long-term treatment of heart failure. The reasons for these detrimental effects are related to the mechanism of action of these drugs, including increases in intracellular Ca2+ with subsequent increases in myocardial oxygen demand and arrhythmogenesis. Levosimendan, a myofilament Ca2+ sensitizer with inotropic effects, increases myocardial performance without substantial changes in oxygen consumption and with neutral effects on heart rhythm. In addition, levosimendan has vasodilatory effects that are achieved by stimulation of adenosine triphosphate-dependent potassium channels. This action may be of specific interest in the setting of myocardial ischemia. To date, levosimendan is approved in 31 countries worldwide, and more patients with heart failure have participated in randomized controlled trials with levosimendan than with any other intravenous inotropic agent.
Levosimendan is a new inotropic and vasodilator agent. The inotropic effect is mediated by calcium concentration-dependent conformational changes in troponin C during systole leading to sensitization of the contractile apparatus to calcium ions. The vasodilator effect is mediated by opening potassium channels on vascular smooth muscle. It has a complex pharmacokinetic profile, with a long-acting metabolite that has hemodynamic effects persisting for approximately 1 week. Although it is absorbed orally, it has been developed only for intravenous use thus far. The hemodynamic effects are not reduced and may be enhanced in the presence of beta-blockers, possibly an important attribute when dealing with exacerbation of heart failure caused by or in the presence of beta-blockers. More patients with heart failure have participated in randomized controlled trials of levosimendan than of any other intravenous inotropic agent. Experience with its use after cardiac surgery is limited. Preliminary observations suggest that hemodynamic changes are associated with symptomatic benefit and a reduction in morbidity and mortality in patients with severe heart failure caused by left ventricular systolic dysfunction, compared with placebo in one study and dobutamine in another. Levosimendan may be the first inotropic agent that it is both safe and effective in altering clinical outcomes relevant for patients. Part of this benefit may be achieved because levosimendan allows other inotropic agents that may have adverse effects on patient outcome to be avoided. Further research is required to confirm whether levosimendan reduces mortality and morbidity compared with a placebo and when administered repetitively. If it does, it may become routine therapy for the treatment of severe heart failure.
OBJECTIVE: Levosimendan is a novel inodilator that improves cardiac contractility by sensitizing troponin C to calcium. This drug has proved to be effective in treating advanced congestive heart failure but has not been evaluated in septic settings. The purpose of the present study was to study the effects of this drug in a porcine model of endotoxemia. DESIGN: Prospective experimental study. SUBJECTS: Fourteen landrace pigs. INTERVENTIONS: All animals were anesthetized and catheterized for measurement of central and pulmonary hemodynamics. Ultrasonic flow probes were placed around the renal artery and portal vein to measure blood flow. A tonometer was placed in the ileum to measure mucosal pH. Levosimendan was given to six animals as a bolus (200 microg x kg(-1)) followed by a continuous infusion (200 microg x kg(-1) x hr(-1)). Thirty minutes after onset of levosimendan treatment, all animals received endotoxin (20 microg x kg(-1) x hr(-1) for 3 hrs). MEASUREMENTS AND MAIN RESULTS: At baseline, levosimendan induced a systemic vasodilation with a reduction in blood pressure and an increase in heart rate. A tendency to an increase in cardiac index did not reach statistical significance (p =.055). Cardiac index and systemic oxygen delivery were markedly improved in the levosimendan group during endotoxemia. Systemic vascular resistance and blood pressure were reduced in the levosimendan group. The latter parameter, however, was only different from the control group during the initial phase of endotoxin shock but not at the late, most pronounced phase of shock. Levosimendan also efficiently attenuated endotoxin-induced pulmonary hypertension. Portal venous blood flow and gut oxygen delivery were improved, but no concomitant reduction in endotoxin-induced intestinal mucosal acidosis was observed. Renal blood flow was unaffected, as was the endotoxin-induced increase in plasma endothelin-1-like immunoreactivity. These findings support previous reports of calcium desensitization as a potential component in septic myocardial depression. Furthermore, the vasodilatory properties of this drug were well tolerated in the current model of hypodynamic endotoxin shock, and they may have contributed to improved regional blood flow as seen in the gut as well as improved systemic perfusion by means of reduced biventricular afterload. CONCLUSION: Pretreatment with levosimendan in pigs subjected to endotoxin shock improved cardiac output and systemic and gut oxygen delivery. In addition, pulmonary hypertension largely was attenuated without any adverse effects on gas exchange. These results are promising in several aspects, but the role of levosimendan in the treating circulatory failure in sepsis remains to be established.
Levosimendan is a novel positive inotropic drug targeted to increase contraction force of the heart through its calcium-dependent binding to troponin C (cTnC). We investigated the calcium-sensitizing effect of levosimendan on contractile proteins as well as its positive inotropic and lusitropic effects in paced guinea pig papillary muscle. We also studied the effect on energy consumption of myosin-actin crossbridges in a myosin ATPase assay. The calcium sensitization induced by levosimendan in fibers skinned with saponin was dependent on the perforation velocity of cell membranes. Levosimendan was almost ineffective in slowly perforated fibers, but was the most potent calcium sensitizer in fibers with rapidly perforated cells. The perforation-dependent calcium sensitization was probably due to changes in phosphorylation state of contractile proteins during the slow dissection of fibers. It is noteworthy that the calcium-sensitizing effect of levosimendan was not affected by acidic pH. Levosimendan at therapeutically relevant (0.3-10 microM) concentrations markedly increased calcium sensitivity both at pH 6.7 and 7.0, being more potent than EMD 53998, pimobendan, and MCI-154. The lack of effect of levosimendan on maximum tension supports the hypothesis that levosimendan increases calcium sensitivity through its action on cTnC. Unlike EMD 53998, levosimendan did not increase myosin ATPase activity, indicating that it did not increase the cycling rate of myosinactin crossbridges. In paced papillary muscles, levosimendan induced positive inotropic effect without changing relaxation time. Thus, levosimendan was devoid of the main negative factors described for calcium sensitizers.
We examined the effects of levosimendan, a new myofilament Ca2+ sensitizer with phosphodiesterase (PDE)-inhibiting properties, on systemic and coronary hemodynamics and left ventricular (LV) systolic and diastolic function in conscious dogs with intact and blocked autonomic nervous system (ANS) reflexes. Twenty experiments were conducted in 10 dogs chronically instrumented for measurement of aortic and LV pressure, the peak rate of increase and decrease in LV pressure (+dP/dtmax and -dP/dtmin), subendocardial segment length, diastolic coronary blood flow (CBF) velocity, and cardiac output (CO). The slope (Mw) of the regional preload recruitable stroke work relation was used to assess myocardial contractility. Diastolic function was evaluated by -dP/dtmin, a time constant of isovolumic relaxation (tau), maximum segment lengthening velocity during rapid ventricular filling (dL/dtmax), and a regional chamber stiffness constant (Kp). Dogs were randomly assigned to receive levosimendan (0.5, 1.0, 2.0, and 4.0 micrograms.kg-1.min-1) with or without ANS blockade. On separate experimental days, systemic and coronary hemodynamics and LV pressure-segment length diagrams and waveforms were recorded after 10-min equilibration at each dose in the conscious ANS-intact or ANS-blocked state. Levosimendan increased heart rate (HR), CO, mean and diastolic CBF velocity, and pressure-work index (PWI, an estimate of myocardial oxygen consumption) and decreased LV end-diastolic pressure (EDP), systemic vascular resistance (SVR), end-systolic and end-diastolic segment length, and mean and diastolic coronary vascular resistance (CVR) in dogs with intact ANS function. Levosimendan-induced increases in HR and PWI and decreases in SVR were attenuated by ANS blockade. Levosimendan caused equivalent dose-dependent increases in Mw in ANS-intact and ANS-blocked dogs, consistent with a positive inotropic effect independent of ANS activity. Levosimendan decreased tau (e.g., 35 +/- 1 ms during control to 29 +/- 1 ms at the high dose) and increased the magnitude of LV -dP/dtmin in dogs with intact but not blocked ANS reflexes, suggesting that relaxation was enhanced by favorable changes in systemic hemodynamics or ANS activation and direct effects of this drug on lusitropic state. Levosimendan also increased dL/dtmax to a greater degree in ANS-intact dogs, indicating that improvement of rapid ventricular filling was also partially dependent on ANS tone. No changes in Kp were observed in either experimental group. The results indicate that levosimendan decreases preload and afterload and has positive inotropic and lusitropic properties. The actions of levosimendan on diastolic function are largely mediated by the ANS.