Inodilator versus inotrope: do inodilators have an edge to improve outcome in patients with heart failure or cardiac dysfunction?

Numerous meta-analyses on inotropes (dobutamine) and inodilators (milrinone, levosimendan) suggest that their impact on survival are at best neutral (but may be deleterious) whereas levosimendan seems to have beneficial effects on survival in patients with acute heart failure (AHF) syndromes. The aim of this essay is to attempt to explain these results through a conceptual framework of cardiocirculatory (patho)physiology. Many clinical studies in AHF have been based and interpreted on a ‘cardiocentric’ framework. The three above-mentioned categories of drugs are thought to increase cardiac output (CO) by increasing only heart muscle contraction (inotropes) or by also decreasing systemic vascular resistance (inodilators). We complement this ‘cardiocentric’ framework with a more integrated one based on (i) the effects of drugs on venous return (VR), equal to CO (VR is the difference between mean systemic and right atrial pressures divided by venous resistance; maintenance of adequate VR depends on the stressed blood volume); inodilators may decrease the stressed volume and therefore may decrease VR; (ii) the coupling of the left ventricle–aorta and right ventricle–pulmonary artery (dependent on the compliance of the large arteries), which is increased by inodilators in the absence of measurable effects on arterial systemic/pulmonary pressures) and (iii) the vascular waterfall phenomenon, which explains that inodilators, by decreasing intra-organ arterial resistance, can improve organ perfusion even in previously mildly hypotensive patients (in the absence of cardiogenic shock). The challenge is to transform these concepts into clinical tools to guide therapy in AHF syndromes

Calcium sensitizers: What have we learned over the last 25years?

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The adenylate cyclase activator forskolin potentiates the positive inotropic effect of the phosphodiesterase inhibitor milrinone but not of the calcium sensitizer levosimendan nor of its hemodynamically active metabolites: an apparent conundrum.

OR-1855 and OR-1896 are two hemodynamically active metabolites of the inodilator levosimendan, with calcium sensitizing activity, but their mechanism of action is still not fully understood.It has been previously reported that the positive inotropic effect of levosimendan is not potentiated by the adenylate cyclase activator forskolin whereas forskolin does potentiate the effects of the phosphodiesterase (PDE) inhibitor milrinone.To ascertain whether the active metabolites follow the same pattern of levosimendan, the positive inotropic effects of OR- 1855 and OR-1896, were studied in guinea-pig isolated papillary muscle in the presence and absence of forskolin. OR-1855 and OR-1896 were also tested as inhibitors of PDE-III and PDE-IV.Our result show that 0.1 µM forskolin did not potentiate the positive inotropic effect of either OR-1855 or OR-1896, as in the case of the parent compound levosimendan. As in previous studies, the positive inotropic effect of milrinone was markedly potentiated in the presence of forskolin.From these data we propose an explanation for the divergent behaviour of the calcium sensitizing drugs and PDE inhibitors

The inodilator levosimendan: 20 years of experience in various settings of cardiac care

Levosimendan emerged in the 1990s as a first-in-class inotrope and vasodilator that enhances cardiac contractility by sensitizing the contractile response to cardiac troponin C and causes vasodilatation by opening potassium-dependent ATP channels on vascular smooth muscle cells. Since its clinical debut in 2000, it has established itself as a valuable resource in the management of acute decompensated heart failure and is one of very few successful medical innovations of its kind in that field in recent decades. Its pharmacology is notable for delivering inotropy without an increase in myocardial oxygen consumption and for an array of secondary (‘pleiotropic’) effects that include an anti-ischemic effect, pre-conditioning and post-conditioning and cardioprotective effects and anti-oxidative effects.Proceeding from those properties it has been proposed that in addition to its use in various scenarios of low cardiac output levosimendan may be beneficial in other conditions associated with acutely decompensated heart failure, including right ventricular failure, subarachnoid hemorrhage, and cardiogenic shock with multi-organ dysfunction. The potential of levosimendan for kidney protection in situations of the cardio-renal syndrome has been identified. Additional lines of investigation include the use of levosimendan for perioperative hemodynamic support, its administration as repeated intermittent infusions to sustain patients with advanced heart failure and its application in a range of critical care settings.Levosimendan has also provided a template and a starting point for the development of a new generation of cardio-active drugs and is currently being evaluated in advanced clinical trials for the management of pulmonary hypertension in patients with heart failure with preserved ejection fraction

Levosimendan improves oxidative balance in cardiogenic shock/low cardiac output patients

The beneficial effects exerted by levosimendan against cardiac failure could be related to the modulation of oxidative balance. We aimed to examine the effects of levosimendan in patients with cardiogenic shock or low cardiac output on cardiac systo-diastolic function and plasma oxidants/antioxidants (glutathione, GSH; thiobarbituric acid reactive substances, TBARS). In four patients undergoing coronary artery bypass grafting or angioplasty, cardiovascular parameters and plasma GSH and TBARS were measured at T0 (before levosimendan infusion), T1 (1 h after the achievement of the therapeutic dosage of levosimendan), T2 (end of levosimendan infusion), T3 (72 h after the end of levosimendan infusion), and T4 (end of cardiogenic shock). We found an improvement in the indices of systolic (ejection fraction, cardiac output, cardiac index) and diastolic (E to early diastolic mitral annular tissue velocity, E/'; early to late diastolic transmitral flow velocity, EA) cardiac function at early T2. A reduction of central venous pressure and pulmonary wedge pressure was also observed. Plasma levels of GSH and TBARS were restored by levosimendan at T1, as well. The results obtained indicate that levosimendan administration can regulate oxidant/antioxidant balance as an early effect in cardiogenic shock/low cardiac output patients. Modulation of oxidative status on a mitochondrial level could thus play a role in exerting the cardio-protection exerted by levosimendan in these patients

Long‐term effects of Na+/Ca2+ exchanger inhibition with ORM‐11035 improves cardiac function and remodelling without lowering blood pressure in a model of heart failure with preserved ejection fraction

Aims: Heart failure with preserved ejection fraction (HFpEF) is increasingly common but there is currently no established pharmacological therapy. We hypothesized that ORM-11035, a novel specific Na+/Ca2+ exchanger (NCX) inhibitor, improves cardiac function and remodelling independent of effects on arterial blood pressure in a model of cardiorenal HFpEF. Methods and results: Rats were subjected to subtotal nephrectomy (NXT) or sham operation. Eight weeks after intervention, treatment for 16 weeks with ORM-11035 (1 mg/kg body weight) or vehicle was initiated. At 24 weeks, blood pressure measurements, echocardiography and pressure–volume loops were performed. Contractile function, Ca2+ transients and NCX-mediated Ca2+ extrusion were measured in isolated ventricular cardiomyocytes. NXT rats (untreated) showed a HFpEF phenotype with left ventricular (LV) hypertrophy, LV end-diastolic pressure (LVEDP) elevation, increased brain natriuretic peptide (BNP) levels, preserved ejection fraction and pulmonary congestion. In cardiomyocytes from untreated NXT rats, early relaxation was prolonged and NCX-mediated Ca2+ extrusion was decreased. Chronic treatment with ORM-11035 significantly reduced LV hypertrophy and cardiac remodelling without lowering systolic blood pressure. LVEDP [14 ± 3 vs. 9 ± 2 mmHg; NXT (n = 12) vs. NXT + ORM (n = 12); P = 0.0002] and BNP levels [71 ± 12 vs. 49 ± 11 pg/mL; NXT (n = 12) vs. NXT + ORM (n = 12); P < 0.0001] were reduced after ORM treatment. LV cardiomyocytes from ORM-treated rats showed improved active relaxation and diastolic cytosolic Ca2+ decay as well as restored NCX-mediated Ca2+ removal, indicating NCX modulation with ORM-11035 as a promising target in the treatment of HFpEF. Conclusion: Chronic inhibition of NCX with ORM-11035 significantly attenuated cardiac remodelling and diastolic dysfunction without lowering systemic blood pressure in this model of HFpEF. Therefore, long-term treatment with selective NCX inhibitors such as ORM-11035 should be evaluated further in the treatment of heart failure

Levosimendan in Europe and China: An Appraisal of Evidence and Context

The calcium sensitiser levosimendan (SIMDAX; Orion Pharma) has been in clinical use for the management of acute heart failure and a range of related syndromes in many countries around the world for two decades. More recently, levosimendan has become available in China. The authors have examined the profile of levosimendan in clinical trials conducted inside and outside China and grouped the findings under six headings: effects on haemodynamics, effects on natriuretic peptides, effect on symptoms of heart failure, renal effects, effect on survival, and safety profile. Their conclusions are that under each of these headings there are reasonable grounds to expect that the effects and clinical benefits established in trials and with wider clinical use in Europe and elsewhere will accrue also to Chinese patients. Therefore, the authors are confident that global experience with levosimendan provides a reliable guide to its optimal use and likely therapeutic effects in patients in China

Efficacy of selective NCX inhibition by ORM-10103 during simulated ischemia/reperfusion.

In this study we evaluated the effects of selective Na+/Ca2+ exchanger (NCX) inhibition by ORM-10103 on the [Ca2+]i transient (CaT), action potential (AP), and cell viability in isolated canine ventricular cardiomyocytes exposed to a simulated ischemia/reperfusion protocol performed either alone (modeling moderate low-flow ischemia) or with simultaneous strophantidine challenge (modeling more severe low-flow ischemia). CaTs were monitored using a Ca2+-sensitive fluorescent dye, APs were recorded by intracellular microelectrodes, and anaerobic shifts in cellular metabolism were verified via monitoring native NADH fluorescence. Simulated ischemia increased the NADH fluorescence, reduced the amplitudes of the AP and CaT and induced membrane depolarization. APs moderately shortened, CaTs prolonged. Diastolic [Ca2+]i ([Ca2+]iD) level increased significantly during ischemia and further elevated following strophantidine application. Reperfusion normalized the NADH level, the amplitude of the AP and duration of the [Ca2+]i transient, but only partially restored action potential triangulation and the amplitude of the CaT. [Ca2+]iD decreased in untreated, but further increased in strophantidine-treated cells. 10microM ORM-10103 significantly reduced the ischemic [Ca2+]i raise in both untreated and strophantidine-treated cells. During reperfusion ORM-10103 decreased [Ca2+]i and eliminated its diastolic elevation in untreated and strophantidine-treated cardiomyocytes. Following the application of ORM-10103 the detrimental effect of ischemia/reperfusion on cell viability and the reperfusion-induced increase in AP and CaT variabilities were substantially reduced, but ischemia-induced shifts in AP morphology were barely influenced. In conclusion, selective NCX inhibition by ORM-10103 is highly effective against ischemia/reperfusion induced pathologic alterations in [Ca2+]i homeostasis, however, it fails to normalize untoward arrhythmogenic changes in AP morphology

Use of levosimendan in acute heart failure

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