Levosimendan attenuates hypoxia-induced pulmonary hypertension in a porcine model

Levosimendan improves central haemodynamic status and gas exchange in a model of ischaemic cardiac arrest: A large animal study

BACKGROUND

Ischaemic cardiac arrest has poor survival. In an earlier animal study, we have shown that levosimendan increases the return of spontaneous circulation and survival compared with placebo. However, the impact of levosimendan on central cardiovascular variables and gas exchange during resuscitation in ischaemic cardiac arrest is unknown.

OBJECTIVE

To evaluate levosimendan's dose-response effect on central cardiovascular variables and gas exchange in an established swine cardiac arrest model.

DESIGN

A large animal study.

SETTING

Animal study with Swedish landrace pigs at Karolinska Institutet, Sweden.

INTERVENTION

Ten swine underwent induced acute myocardial infarction and ventricular fibrillation. Levosimendan (62.5 μg kg -1 ) was administered during resuscitation, and immediate outcomes were compared with low dose levosimendan (12 μg kg -1 , n   =  12) or placebo ( n   =  12) from earlier experiments using the same model.

MAIN OUTCOME MEASURES

Haemodynamic and gas exchange variables during resuscitation. Time to and proportion of return to spontaneous circulation.

RESULTS

High-dose levosimendan improved gas exchange, with better arterial O 2 and CO 2 levels ( P  < 0.01), reduced systolic pulmonary arterial pressure, central venous pressure and vasopressor support with adrenaline after return to spontaneous circulation compared with low dose and placebo ( P  = 0.01). All animals in both levosimendan groups achieved return to spontaneous circulation compared with 67% in the placebo group ( P  = 0.02). Median [IQR] time to return of spontaneous circulation was 15 min [12 to 18] for high dose 17 min [15 to 26] for low dose compared with 23 min [15 to 60] for placebo ( P  = 0.08).

CONCLUSIONS

Levosimendan enhances key resuscitation outcomes in the immediate period of ischaemic cardiac arrest, promoting its potential as an effective pharmacological intervention. With an apparent dose-dependent reduction in right ventricular afterload and subsequent improvement in gas exchange, we cautiously propose that levosimendan-induced pulmonary vasodilation alleviates right heart strain and improves interventricular dependency, thereby enhancing the likelihood of return of spontaneous circulation.

Levosimendan mediates the BMP/Smad axis through upregulation of circUSP34-targeted miR-1298 to alleviate pulmonary hypertension

BACKGROUND

Pulmonary hypertension (PH) is a long-term disease that impacts approximately 1% of the world's population. Currently, levosimendan (Lev) is proposed for PH treatment. However, the mechanism of Lev in the treatment of PH is unknown.

METHODS

We used hypoxia-induced pulmonary artery smooth muscle cells (PASMCs) to establish a PH cell model. A number of cell biology methods were performed to assay alterations in cell proliferation, migration and apoptosis after Lev treatment. qRT-PCR and WB were performed to test the levels of circUSP34 and miR-1298, and BMP/Smad protein respectively. In addition, the regulatory relationship between circUSP34 or BMPR2 with miR-1298 was verified through the use of double luciferase as well as RIP assay. In addition, we explored the regulatory effect of Lev on the circUSP34/miR-1298/BMP/Smad axis using a rat PH model.

RESULTS

Our results demonstrate that Lev inhibited PASMCs cell proliferation, migration and promoted apoptosis exposed to hypoxia. In hypoxia-treated PASMCs, circUSP34 expression got downregulated while miR-1298 upregulated, whereas the addition with Lev resulted in upregulation of circUSP34 expression and downregulation of miR-1298 expression, indicating that circUSP34 can target and regulate miR-1298. In addition, miR-1298 targets and regulates the expression of BMPR2. In a rat PH model induced by hypoxia combined with SU5416, Lev upregulated circUSP34 targeting miR-1298-mediated BMP/Smad axis to alleviate the PH phenotype.

CONCLUSION

We have shown that Lev can be used as a therapeutic drug for PH patients, which works through the circUSP34/miR-1298/BMP/Smad axis to alleviate PH symptoms.

Pressure Overload and Right Ventricular Failure: From Pathophysiology to Treatment

Right ventricular failure (RVF) is often caused by increased afterload and disrupted coupling between the right ventricle (RV) and the pulmonary arteries (PAs). After a phase of adaptive hypertrophy, pressure-overloaded RVs evolve towards maladaptive hypertrophy and finally ventricular dilatation, with reduced stroke volume and systemic congestion. In this article, we review the concept of RV-PA coupling, which depicts the interaction between RV contractility and afterload, as well as the invasive and non-invasive techniques for its assessment. The current principles of RVF management based on pathophysiology and underlying etiology are subsequently discussed. Treatment strategies remain a challenge and range from fluid management and afterload reduction in moderate RVF to vasopressor therapy, inotropic support and, occasionally, mechanical circulatory support in severe RVF.

Effect of Levosimendan on Acute Decompensated Right Heart Failure in Patients With Connective Tissue Disease-Associated Pulmonary Arterial Hypertension

Aims

Acute decompensated right heart failure (RHF) in chronic precapillary pulmonary hypertension is often typified by a swiftly progressive syndrome involving systemic congestion. This results from the impairment of the right ventricular filling and/or a reduction in the flow output of the right ventricle, which has been linked to a dismal prognosis of short duration. Despite this, there are limited therapeutic data regarding these acute incidents. This study examined the effect of levosimendan on acute decompensated RHF in patients with connective tissue disease-associated pulmonary arterial hypertension (CTD-PAH).

Methods

This retrospective study included 87 patients with confirmed CTD-PAH complicated acute decompensated RHF between November 2015 and April 2021. We collected biological, clinical, and demographic data, as well as therapy data, from patients with acute decompensated RHF who required levosimendan treatment in the cardiac care unit (CCU) for CTD-PAH. The patients were divided into two groups according to the levosimendan treatment. Patient information between the two groups was systematically compared in hospital and at follow-up.

Results

Oxygen saturation of mixed venose blood (SvO₂), estimated glomerular filtration rate (eGFR), 24-h urine output, and tricuspid annular plane systolic excursion (TAPSE) were found to be considerably elevated in the levosimendan cohort compared with the control cohort. Patients in the levosimendan cohort exhibited considerably reduced levels of C-reactive protein (CRP), white blood cell (WBC), troponin I, creatinine, NT-proBNP, and RV diameter compared with those in the control cohort. A higher survival rate was observed in the levosimendan cohort.

Conclusions

Levosimendan treatment could effectively improve acute decompensated RHF and systemic hemodynamics in CTD-PAH patients, with positive effects on survival in hospital and can, therefore, be considered as an alternative treatment option for improving clinical short-term outcomes.

Levosimendan, milrinone, and dobutamine in experimental acute pulmonary embolism

Acute pulmonary embolism is a frequent condition in emergency medicine and potentially fatal. Cause of death is right ventricular failure due to increased right ventricular afterload from both pulmonary vascular obstruction and vasoconstriction. Inodilators are interesting drugs of choice as they may improve right ventricular function and lower its afterload. We aimed to investigate the cardiovascular effects of three clinically relevant inodilators: levosimendan, milrinone, and dobutamine in acute pulmonary embolism. We conducted a randomized, blinded, animal study using 18 female pigs. Animals received large autologous pulmonary embolism until doubling of baseline mean pulmonary arterial pressure and were randomized to increasing doses of each inodilator. Effects were evaluated with bi-ventricular pressure–volume loop recordings, right heart catheterization, and blood gas analyses. Induction of pulmonary embolism increased right ventricular afterload and pulmonary pressure (p < 0.05) causing right ventricular dysfunction. Levosimendan and milrinone showed beneficial hemodynamic profiles by lowering right ventricular pressures and volume (p < 0.001) and improved right ventricular function and cardiac output (p < 0.05) without increasing right ventricular mechanical work. Dobutamine increased right ventricular pressure and function (p < 0.01) but at a cost of increased mechanical work at the highest doses, showing an adverse hemodynamic profile. In a porcine model of acute pulmonary embolism, levosimendan and milrinone reduced right ventricular afterload and improved right ventricular function, whereas dobutamine at higher doses increased right ventricular afterload and right ventricular mechanical work. The study motivates clinical testing of inodilators in patients with acute pulmonary embolism and right ventricular dysfunction.

Levosimendan reduces segmental pulmonary vascular resistance in isolated perfused rat lungs and relaxes human pulmonary vessels

INTRODUCTION

Levosimendan is approved for acute heart failure. Within this context, pulmonary hypertension represents a frequent co-morbidity. Hence, the effects of levosimendan on segmental pulmonary vascular resistance (PVR) are relevant. So far, this issue has been not studied. Beyond that the relaxant effects of levosimendan in human pulmonary vessel are unknown. We addressed these topics in rats' isolated perfused lungs (IPL) and human precision-cut lung slices (PCLS).

MATERIAL AND METHODS

In IPL, levosimendan (10 μM) was perfused in untreated and endothelin-1 pre-contracted lungs. The pulmonary arterial pressure (PPA) was continuously recorded and the capillary pressure (Pcap) was determined by the double-occlusion method. Thereafter, segmental PVR, expressed as precapillary (Rpre) and postcapillary resistance (Rpost) and PVR were calculated. Human PCLS were prepared from patients undergoing lobectomy. Levosimendan-induced relaxation was studied in naïve and endothelin-1 pre-contracted PAs and PVs. In endothelin-1 pre-contracted PAs, the role of K+-channels was studied by inhibition of KATP-channels (glibenclamide), BKCa2+-channels (iberiotoxin) and Kv-channels (4-aminopyridine). All changes of the vascular tone were measured by videomicroscopy. In addition, the increase of cAMP/GMP due to levosimendan was measured by ELISA.

RESULTS

Levosimendan did not relax untreated lungs or naïve PAs and PVs. In IPL, levosimendan attenuated the endothelin-1 induced increase of PPA, PVR, Rpre and Rpost. In human PCLS, levosimendan relaxed pre-contracted PAs or PVs to 137% or 127%, respectively. In pre-contracted PAs, the relaxant effect of levosimendan was reduced, if KATP- and Kv-channels were inhibited. Further, levosimendan increased cGMP in PAs/PVs, but cAMP only in PVs.

DISCUSSION

Levosimendan reduces rats' segmental PVR and relaxes human PAs or PVs, if the pulmonary vascular tone is enhanced by endothelin-1. Regarding levosimendan-induced relaxation, the activation of KATP- and Kv-channels is of impact, as well as the formation of cAMP and cGMP. In conclusion, our results suggest that levosimendan improves pulmonary haemodynamics, if PVR is increased as it is the case in pulmonary hypertension.

Levosimendan in the light of the results of the recent randomized controlled trials: an expert opinion paper

Despite interesting and unique pharmacological properties, levosimendan has not proven a clear superiority to placebo in the patient populations that have been enrolled in the various recent multicenter randomized controlled trials. However, the pharmacodynamic effects of levosimendan are still considered potentially very useful in a number of specific situations.Patients with decompensated heart failure requiring inotropic support and receiving beta-blockers represent the most widely accepted indication. Repeated infusions of levosimendan are increasingly used to facilitate weaning from dobutamine and avoid prolonged hospitalizations in patients with end-stage heart failure, awaiting heart transplantation or left ventricular assist device implantation. New trials are under way to confirm or refute the potential usefulness of levosimendan to facilitate weaning from veno-arterial ECMO, to treat cardiogenic shock due to left or right ventricular failure because the current evidence is mostly retrospective and requires confirmation with better-designed studies. Takotsubo syndrome may represent an ideal target for this non-adrenergic inotrope, but this statement also relies on expert opinion. There is no benefit from levosimendan in patients with septic shock. The two large trials evaluating the prophylactic administration of levosimendan (pharmacological preconditioning) in cardiac surgical patients with poor left ventricular ejection fraction could not show a significant reduction in their composite endpoints reflecting low cardiac output syndrome with respect to placebo. However, the subgroup of those who underwent isolated CABG appeared to have a reduction in mortality. A new study will be required to confirm this exploratory finding.Levosimendan remains a potentially useful inodilator agent in a number of specific situations due to its unique pharmacological properties. More studies are needed to provide a higher level of proof regarding these indications.

Levosimendan in pulmonary hypertension and right heart failure

Pulmonary hypertension is a multifactorial disease with a high morbidity and mortality. Right ventricular function is the most important predictor of morbidity and mortality in patients suffering from pulmonary hypertension, but currently there are no approved treatments directly supporting the failing right ventricle. Levosimendan is a calcium sensitizing agent with inotropic, pulmonary vasodilatory, and cardioprotective properties. Given its pharmacodynamic profile, levosimendan could be a potential novel agent for the treatment of right ventricular failure caused by pulmonary hypertension. The aim of this review is to provide an overview of the current knowledge on the effects of levosimendan in pulmonary hypertension and right heart failure.

Acute effects of levosimendan in experimental models of right ventricular hypertrophy and failure

Pulmonary arterial hypertension (PAH) is a fatal disease, and the ultimate cause of death is right ventricular (RV) failure. In this study, we investigated the acute hemodynamic effects of levosimendan in two rat models of RV hypertrophy and failure. Wistar rats were randomized to receive sham surgery (n = 8), pulmonary trunk banding (PTB; n = 8), or monocrotaline injection (MCT; n = 7). RV function was evaluated at baseline and after injection of placebo and two concentrations of levosimendan (12 and 60 μg/kg) using magnetic resonance imaging, echocardiography, and invasive pressure recordings. PTB and MCT injection caused hypertrophy, dilatation, and failure of the RV compared with sham surgery. Levosimendan increased RV end systolic pressure (sham surgery: 16.0% ± 3.8% [P = 0.0038]; MCT: 9.9% ± 3.1% [P = 0.018]; PTB: 24.5% ± 3.3% [P = 0.0001]; mean ± SEM) compared with placebo. Levosimendan markedly increased RV stroke volume (SV) in the MCT group (29.1% ± 8.3%; P = 0.012), did not change RV SV in the PTB group (0.4% ± 4.5%; P = 0.93), and decreased RV SV in the sham surgery group (-10.9% ± 3.7%; P = 0.020). Nitroprusside, which was used to mimic the systemic arterial vasodilator action of levosimendan, did not influence RV function. These data demonstrate that levosimendan acutely improves the failing right heart in a MCT model of PAH and that the mechanism involves a direct acute positive inotropic effect on the hypertrophic and failing RV of the rat.

P2Y₁ and P2Y₁₂ receptors in hypoxia- and adenosine diphosphate-induced pulmonary vasoconstriction in vivo in the pig

PURPOSE

To investigate the role of P2Y₁ and P2Y₁₂ receptors in hypoxia- and adenosine diphosphate (ADP)-induced pulmonary vasoconstriction.

METHODS

19 anaesthetized, mechanically ventilated pigs (31.3 ± 0.7 kg) were evaluated in normoxia and hypoxia, without (n = 6) or with P2Y₁ receptor antagonist MRS2500 (n = 7) or P2Y₁₂ receptor antagonist cangrelor (n = 6) treatment. 12 pigs (29.3 ± 0.4 kg) were evaluated before and during ADP infusion, without and with MRS2500 (n = 6) or cangrelor (n = 6) pre-treatment.

RESULTS

Hypoxia increased (p < 0.05) mean pulmonary artery pressure (MPAP) by 14.2 ± 1.1 mmHg and pulmonary vascular resistance (PVR) by 2.7 ± 0.4 WU. Without treatment MPAP and PVR remained unaltered (p = ns) for 90 min hypoxia. During hypoxia MRS2500 decreased (p < 0.013) MPAP by 4.3 ± 1.2 mmHg within 15 min. Cangrelor decreased (p < 0.036) MPAP to be 3.3 ± 0.4 and 3.6 ± 0.6 mmHg lower than hypoxia baseline after 10 and 30 min. PVR was, however, unaltered (p = ns) by MRS2500 or cangrelor during hypoxia. ADP increased (p < 0.001) MPAP and PVR to stabilize 11.1 ± 1.3 mmHg and 2.7 ± 0.3 WU higher than baseline. MRS2500 or cangrelor pre-treatment totally abolished the sustained MPAP- and PVR-increases to ADP.

CONCLUSIONS

ADP elicits pulmonary vasoconstriction through P2Y₁ and P2Y₁₂ receptor activation. ADP is not a mandatory modulator, but may still contribute to pulmonary vascular tone during acute hypoxia. Further investigations into the mechanisms behind ADP-induced pulmonary vasoconstriction and the role of ADP as a modulator of pulmonary vascular tone during hypoxia are warranted.