Levosimendan as a new force in the treatment of sepsis-induced cardiomyopathy: mechanism and clinical application

Apelin-13 administration allows for norepinephrine sparing in a rat model of cecal ligation and puncture-induced septic shock

BACKGROUND

Infusion of exogenous catecholamines (i.e., norepinephrine [NE] and dobutamine) is a recommended treatment for septic shock with myocardial dysfunction. However, sustained catecholamine infusion is linked to cardiac toxicity and impaired responsiveness. Several pre-clinical and clinical studies have investigated the use of alternative vasopressors in the treatment of septic shock, with limited benefits and generally no effect on mortality. Apelin-13 (APL-13) is an endogenous positive inotrope and vasoactive peptide and has been demonstrated cardioprotective with vasomodulator and sparing life effects in animal models of septic shock. A primary objective of this study was to evaluate the NE-sparing effect of APL-13 infusion in an experimental sepsis-induced hypotension.

METHODS

For this goal, sepsis was induced by cecal ligation and puncture (CLP) in male rats and the arterial blood pressure (BP) monitored continuously via a carotid catheter. Monitoring, fluid resuscitation and experimental treatments were performed on conscious animals. Based on pilot assays, normal saline fluid resuscitation (2.5 mL/Kg/h) was initiated 3 h post-CLP and maintained up to the endpoint. Thus, titrated doses of NE, with or without fixed-doses of APL-13 or the apelin receptor antagonist F13A co-infusion were started when 20% decrease of systolic BP (SBP) from baseline was achieved, to restore SBP values ≥ 115 ± 1.5 mmHg (baseline average ± SEM).

RESULTS

A reduction in mean NE dose was observed with APL-13 but not F13A co-infusion at pre-determined treatment time of 4.5 ± 0.5 h (17.37 ± 1.74 µg/Kg/h [APL-13] vs. 25.64 ± 2.61 µg/Kg/h [Control NE] vs. 28.60 ± 4.79 µg/Kg/min [F13A], P = 0.0491). A 60% decrease in NE infusion rate over time was observed with APL-13 co-infusion, (p = 0.008 vs NE alone), while F13A co-infusion increased the NE infusion rate over time by 218% (p = 0.003 vs NE + APL-13). Associated improvements in cardiac function are likely mediated by (i) enhanced left ventricular end-diastolic volume (0.18 ± 0.02 mL [Control NE] vs. 0.30 ± 0.03 mL [APL-13], P = 0.0051), stroke volume (0.11 ± 0.01 mL [Control NE] vs. 0.21 ± 0.01 mL [APL-13], P < 0.001) and cardiac output (67.57 ± 8.63 mL/min [Control NE] vs. 112.20 ± 8.53 mL/min [APL-13], P = 0.0036), and (ii) a reduced effective arterial elastance (920.6 ± 81.4 mmHg/mL/min [Control NE] vs. 497.633.44 mmHg/mL/min. [APL-13], P = 0.0002). APL-13 administration was also associated with a decrease in lactate levels compared to animals only receiving NE (7.08 ± 0.40 [Control NE] vs. 4.78 ± 0.60 [APL-13], P < 0.01).

CONCLUSION

APL-13 exhibits NE-sparing benefits in the treatment of sepsis-induced shock, potentially reducing deleterious effects of prolonged exogenous catecholamine administration.

Research Progress on Mechanisms and Treatment of Sepsis-Induced Myocardial Dysfunction

Sepsis is a syndrome of organ dysfunction caused by a dysregulated immune response to infection, with high morbidity and mortality. At present, there have been many advances in the study of its pathogenesis, especially the cardiac dysfunction caused by sepsis, namely sepsis-induced myocardial dysfunction, SIMD, which has received widespread attention. The mechanisms of SIMD mainly include excessive release of inflammatory mediators, impaired mitochondrial function, autophagy, apoptosis and myocardial dysfunction. This article reviews the pathogenesis of SIMD and elaborates on the progress in its treatment, aiming to improve the prognosis of patients with SIMD and sepsis.

Development and validation of a nomogram to predict risk of septic cardiomyopathy in the intensive care unit

The aim of this study was to develop a simple but effective nomogram to predict risk of septic cardiomyopathy (SCM) in the intensive care unit (ICU). We analyzed data from patients who were first admitted to the ICU for sepsis between 2008 and 2019 in the MIMIC-IV database, with no history of heart disease, and divided them into a training cohort and an internal validation cohort at a 7:3 ratio. SCM is defined as sepsis diagnosed in the absence of other cardiac diseases, with echocardiographic evidence of left (or right) ventricular systolic or diastolic dysfunction and a left ventricular ejection fraction (LVEF) of less than 50%. Variables were selected from the training cohort using the Least Absolute Shrinkage and Selection Operator (LASSO) regression to develop an early predictive model for septic cardiomyopathy. A nomogram was constructed using logistic regression analysis and its receiver operating characteristic (ROC) and calibration were evaluated in two cohorts. A total of 1562 patients participated in this study, with 1094 in the training cohort and 468 in the internal validation cohort. SCM occurred in 13.4% (147 individuals) in the training cohort, 16.0% (75 individuals) in the internal validation cohort. After adjusting for various confounding factors, we constructed a nomogram that includes SAPS II, Troponin T, CK-MB index, white blood cell count, and presence of atrial fibrillation. The area under the curve (AUC) for the training cohort was 0.804 (95% CI 0.764-0.844), and the Hosmer-Lemeshow test showed good calibration of the nomogram (P = 0.288). Our nomogram also exhibited good discriminative ability and calibration in the internal validation cohort. Our nomogram demonstrated good potential in identifying patients at increased risk of SCM in the ICU.

Efficacy and safety of levosimendan in patients with sepsis: a systematic review and network meta-analysis

Objective: We conducted a systematic review to assess the advantages and disadvantages of levosimendan in patients with sepsis compared with placebo, milrinone, and dobutamine and to explore the clinical efficacy of different concentrations of levosimendan. Methods: PubMed, Web of Science, Cochrane Library, Embase, CNKI, Wanfang data, VIP, and CBM databases were searched using such keywords as simendan, levosimendan, and sepsis. The search time was from the establishment of the database to July 2023. Two researchers were responsible for literature screening and data collection respectively. After the risk of bias in the included studies was evaluated, network meta-analysis was performed using R software gemtc and rjags package. Results: Thirty-two randomized controlled trials (RCTs) were included in the network meta-analysis. Meta-analysis results showed that while levosimendan significantly improved CI levels at either 0.1 µg/kg/min (mean difference [MD] [95%CrI] = 0.41 [-0.43, 1.4]) or 0.2 µg/kg/min (MD [95%CrI] =0.54 [0.12, 0.99]). Levosimendan, at either 0.075 µg/kg/min (MD [95% CrI] =0.033 [-0.75, 0.82]) or 0.2 µg/kg/min (MD [95% CrI] = -0.014 [-0.26, 0.23]), had no significant advantage in improving Lac levels. Levosimendan, at either 0.1 µg/kg/min (RR [95% CrI] = 0.99 [0.73, 1.3]) or 0.2 µg/kg/min (RR [95% CrI] = 1.0 [0.88, 1.2]), did not have a significant advantage in reducing mortality. Conclusion: The existing evidence suggests that levosimendan can significantly improve CI and lactate levels in patients with sepsis, and levosimendan at 0.1 µg/kg/min might be the optimal dose. Unfortunately, all interventions in this study failed to reduce the 28-day mortality. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023441220.

Efficacy of Levosimendan in the Treatment of Patients With Severe Septic Cardiomyopathy

OBJECTIVE

This study was designed to compare the effects of levosimendan and dobutamine on hemodynamics and clinical efficacy in patients with severe septic cardiomyopathy (left ventricular ejection fraction [LVEF] ≤35%).

DESIGN

A prospective, single-blind, randomized controlled study.

SETTING

In Baoding, China.

PARTICIPANTS

Thirty patients with severe septic cardiomyopathy treated in the authors' hospital's Department of Critical Medicine from September 2018 to September 2021 were enrolled in this study.

INTERVENTIONS

These patients were divided randomly into the levosimendan group and dobutamine group. The LVEF, cardiac index (CI), stroke volume index (SVI), systemic vascular resistance index, heart rate, norepinephrine dose, and lactate at the time of enrollment and the 24th hour were compared, along with myocardial injury markers on the third day, C-reactive protein, mechanical ventilation time, length of intensive care unit (ICU) stay, cost, and 28-day mortality. The primary outcome was 28-day mortality.

MEASUREMENTS AND MAIN RESULTS

At the 24th hour after treatment, CI, LVEF, SVI, and fluid volume were found to be higher in the levosimendan group than in the dobutamine group, whereas the dose of norepinephrine was lower in the former rather than the latter group. On the third day of treatment, cardiac troponin I in the levosimendan group was lower than that in the dobutamine group. Although the differences in 28-day mortality, ICU stay, and ICU treatment cost between the groups were not statistically significant, the ventilator application time of the levosimendan group was significantly shorter than that of the dobutamine group.

CONCLUSIONS

Compared with dobutamine, levosimendan was more effective at improving cardiac function, reducing myocardial injury, and reducing mechanical ventilation time in patients with severe septic cardiomyopathy.

Levosimendan Increases Survival in a D-Galactosamine and Lipopolysaccharide Rat Model

Levosimendan, a calcium sensitizer, has an organ protective profile through the inhibition of inflammatory mediators and cytokines in critical conditions, such as heart failure, ischemia-reperfusion injury, and sepsis. The survival effect of levosimendan for acute liver failure has not been examined yet. Male Sprague-Dawley rats were examined in the D-galactosamine hydrochloride and lipopolysaccharide (GalN/LPS) model. Levosimendan was injected intraperitoneally before GalN/LPS treatment. Survival was monitored for 7 days. For biochemical analyses, liver and blood samples were collected from the rats at 1 and 8 h after GaIN/LPS treatment. The pretreatment of levosimendan at 4 mg/kg significantly increased survival in GalN/LPS rats. In the liver specimen, levosimendan significantly inhibited the activation of nuclear factor-κB (NF-κB) at 1 h, and significantly decreased the mRNA expression of inflammatory mediators, including inducible nitric oxide synthase and tumor necrosis factor-α (TNF-α), at 8 h. In serum, levosimendan decreased the levels of nitrite, a metabolite of nitric oxide, and TNF-α protein, as well as aspartate aminotransferase and alanine aminotransferase. These results indicated that Levosimendan ameliorated liver dysfunction and survival in acute liver failure model rats through the suppression of NF-κB activation.

Levosimendan: mechanistic insight and its diverse future aspects in cardiac care

Inotropic agents are generally recommended to use in patients with acute decompensated heart failure (HF) with reduced ejection fraction (HFrEF) concurrent to end-organ dysfunction. However, due to certain pharmacological limitations like developing life threatening arrhythmia and tolerance, cannot be employed as much as needed. Meanwhile, Calcium ion (Ca²⁺) sensitisers exhibits their inotropic action by increasing the sensitivity of the cardiomyocyte to intracellular Ca²⁺ ion and have been reported as emerging therapeutic alternative in HF cases. Levosimendan (LEVO) is an inodilator and with its unique pharmacology justifying its use in a wide range of cardiac alterations in HF particularly in undergoing cardiac surgery. It is also reported to be better than classical inotropes in maintaining cardiac mechanical efficacy and reducing congestion in acute HF with hypotension. This review paper was designed to compile various evidence about basic pharmacology and potential clinical aspects of LEVO in cardiac surgery and other HF associated alterations. This will benefit directly to the researcher in initiating research and to fill the gaps in the area of thrust.

Progress in the Clinical Assessment and Treatment of Myocardial Depression in Critically Ill Patient with Sepsis

Myocardial inhibition is the main cause of death in patients with sepsis.In recent years, methodological differences in the diagnosis, assessment, and treatment of septic myocardial depression have been observed, and how to objectively and accurately evaluate the degree of myocardial depression and the timing of treatment strategies have generally been the focus of this area of research. Based on the relevant research at home and abroad, the current review summarizes the clinical characteristics, methodological diagnosis, and symptomatic treatment of septic myocardial depression. The aim of doing so is to provide a reference for the early identification and treatment of patients with sepsis and myocardial depression.

Research Progress on the Mechanism of Sepsis Induced Myocardial Injury

Sepsis is an abnormal condition with multiple organ dysfunctions caused by the uncontrolled infection response and one of the major diseases that seriously hang over global human health. Besides, sepsis is characterized by high morbidity and mortality, especially in intensive care unit (ICU). Among the numerous subsequent organ injuries of sepsis, myocardial injury is one of the most common complications and the main cause of death in septic patients. To better manage septic inpatients, it is necessary to understand the specific mechanisms of sepsis induced myocardial injury (SIMI). Therefore, this review will elucidate the pathophysiology of SIMI from the following certain mechanisms: apoptosis, mitochondrial damage, autophagy, excessive inflammatory response, oxidative stress and pyroptosis, and outline current therapeutic strategies and potential approaches in SIMI.

Comparison of dobutamine and levosimendan for treatment of sepsis-induced cardiac dysfunction: A protocol for systematic review and meta-analysis

BACKGROUND

Levosimendan and dobutamine are extensively used to treat sepsis-induced cardiomyopathy. Previous studies on whether levosimendan is superior to dobutamine are still controversial. We performed a protocol for systematic review and metaanalysis to compare the efficacy and safety of levosimendan versus dobutamine for the treatment of sepsis-induced cardiomyopathy.

METHODS

This protocol follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol statement. We will search the following databases: PubMed, Embase, Web of Science, Cochrane Library, China National Knowledge Infrastructure, Wanfang Database, Weipu Journal Database, and Chinese Biomedical Literature Database. The search time will be set from database establishment to February 2022. After literature screening, 2 reviewers will extract data from the respects of general information, methodology, and results. Risk of bias is assessed using the Cochrane Risk of Bias Tool for randomized controlled trials. We will apply RevMan 5.4 software for statistical analysis.

RESULTS

The results will be submitted to a peer-reviewed journal once completed.

CONCLUSION

Septic patients with myocardial dysfunction may partly benefit from levosimendan than dobutamine, mainly embodied in cardiac function improvement.

Levosimendan Postconditioning Attenuates Cardiomyocyte Apoptosis after Myocardial Infarction

BACKGROUND

Levosimendan preconditioning has been shown to attenuate myocardial apoptosis in animal models. However, protective effects of levosimendan postconditioning against myocardial apoptosis following myocardial infarction (MI) have not been evaluated. Therefore, we investigated the effects of levosimendan postconditioning on myocardial apoptosis in MI rat models.

METHODS

In an anoxia/reoxygenation (A/R) model, H9c2 cells were pretreated with or without levosimendan postconditioning after which their apoptosis rates were assessed by flow cytometry, RT-qPCR, and western blot analyses. Then, postconditioning was performed with or without levosimendan in MI rat models. Myocardiocyte apoptosis was evaluated by echocardiography, TTC staining, TUNEL staining, immunohistochemical staining, RT-qPCR, and western blot analysis.

RESULTS

Levosimendan postconditioning inhibited H9c2 cell apoptosis in A/R models by elevating Bcl-2 while suppressing Caspase-3 and Bax at both mRNA and protein levels. Moreover, it improved cardiac functions and reduced the left ventricle infarction area in MI rat models. Compared to the MI control group, cardiomyocyte apoptosis rates in the levosimendan postconditioning group were low. The reduced cardiomyocyte apoptosis rates were associated with downregulation of Bax and Caspase-3 as well as with upregulation of Bcl-2 at mRNA and protein levels.

CONCLUSIONS

Levosimendan postconditioning of MI rat models protected against cardiomyocyte apoptosis, implying that it is a potential strategy for preventing cardiomyocyte apoptosis in the treatment of cardiac dysfunction following MI.

Effects of extracellular histones on left ventricular diastolic function and potential mechanisms in mice with sepsis

OBJECTIVE

Extracellular histone (EH) is involved in the development of septic myocardial injury (SMI). In this study, we explored whether EH could induce left ventricular diastolic dysfunction (LVDD) in sepsis, and investigated the potential mechanisms through in vivo and in vitro experiments using animal models.

METHODS

The ratio between E-wave and A-wave (E/A ratio), left ventricular end diastolic volume, and isovolumic relaxation time (IVRT) were measured in cecal ligation and perforation (CLP)- and EH-treated male C57BL/6J mice using echocardiography. The protein and mRNA levels of apoptosis-related proteins (cleaved caspase-3, Bcl-2, and Bax) and cardiac troponin T (cTnT) in the left ventricular tissue/cardiomyocytes were measured using enzyme-linked immunosorbent assay, qRT-PCR, and western blotting. Cardiomyocyte apoptosis was detected by flow cytometry.

RESULTS

CLP mice presented with LVDD, which was accompanied by increased circulating histones, cTnT and Bax protein levels. Circulating histones were correlated with cTnT, Bax, IVRT, and E/A ratio in CLP mice. Intraperitoneal injection of EH resulted in LVDD in mice. EH induced cardiomyocyte apoptosis, and histone neutralizing agents improved SMI and protected mice against CLP- and EH-induced death.

CONCLUSION

EH is involved in septic LVDD, and this alteration might be associated with EH-induced apoptosis. EH may serve as a potential therapeutic target for SMI.

Beyond the bundle: Clinical controversies in the management of sepsis in emergency medicine patients

Sepsis is a condition characterized by life-threatening organ dysfunction caused by a dysregulated host response to infection. The emergency department (ED) serves as a crucial entry point for patients presenting with sepsis. Given the heterogeneous presentation and high mortality rate associated with sepsis and septic shock, several clinical controversies have emerged in the management of sepsis. These include the use of novel therapeutic agents like angiotensin II, hydrocortisone, ascorbic acid, thiamine ("HAT") therapy, and levosimendan, Additionally, controversies with current treatments in vasopressor dosing, and the use of and balanced or unbalanced crystalloid are crucial to consider. The purpose of this review is to discuss clinical controversies in the management of septic patients, including the use of novel medications and dosing strategies, to assist providers in appropriately determining what treatment strategy is best suited for patients.

MiR-702-3p inhibits the inflammatory injury in septic H9c2 cells by regulating NOD1

BACKGROUND

Cardiac insufficiency is a common complication of sepsis and septic shock and is the most common cause of death in critically ill patients. Recent studies have found that microRNAs (miRNAs) play a potential role in sepsis as markers, but little is known about their functional effects on sepsis-induced cardiomyopathy (SIC).

OBJECTIVE

This study is designed to explore the possible role and underlying mechanisms of miR-702-3p in septic cardiomyopathy.

METHODS

As expected, H9c2 cells were induced with lipopolysaccharide (LPS) to construct the model of septic cardiomyopathy. The expression of miR-702-3p was detected by qRT-PCR assay and those of IL-1β, IL-6 and TNF-α by ELISA assay. The viability, proliferation and apoptosis of LPS-treated H9c2 cells were determined by CCK-8, EdU, flow cytometry and western blot assays. Moreover, Nucleotide-binding oligomerization domain-containing protein 1 (NOD1) was predicted and confirmed as a direct target of miR-702-3p by TargetScan, miRwalk and miRDB prediction and dual-luciferase reporter gene assays.

RESULTS

While LPS can weaken the viability of H9c2 cells, miR-702-3p enhances that of LPS-treated H9c2 cells by inhibit the expressions of TNF-α, IL-6, IL-1β. We found NOD1 is a target gene of miR-702-3p, and over-expression of NOD1 restores the inhibitory effects of miR-702-3p on the LPS-treated H9c2 cells.

CONCLUSION

MiR-702-3p played an important role in the pathogenesis of sepsis cardiomyopathy via targeting NOD1, suggesting that miR-702-3p may be a potential new target for the treatment of SIC.

Diagnostic value and significance of serum miR-132 combined with miR-223 for sepsis-induced cardiomyopathy

In previous studies, miR-132 and miR-223 were considered to be involved in cellular and pathological processes of diseases. However, the role of early diagnosis and prognosis evaluation in sepsis-induced cardiomyopathy (SIC) remains unknown. The present study aimed to explore the diagnostic value of combined detection of miR-132 and miR-223 for SIC and their correlation with creatine kinase-MB (CK-MB), cardiac troponin I (cTnI), tumor necrosis factor α (TNF-α), and interleukin-6 (IL)-6. SIC patients (n=80) admitted to Tianjin Medical University General Hospital were assigned to the research group (RG), while 60 healthy participants receiving physical examinations at the same period were assigned to the control group (CG). Serum expression profiles of miR-132 and miR-223 were detected by the RT-qPCR. CK-MB and cTnI were assessed using chemiluminescence assay, and TNF-α and IL-6 by enzyme-linked immunosorbent assay (ELISA). Serum miR-132 and miR-223 levels were significantly lower in the RG than in the CG (P<0.001). The sensitivity and specificity for the diagnosis of SIC were 82.50 and 71.67% for miR-132, 95.00 and 61.67% for miR-223, as well as 86.25 and 86.67% for miR-132 combined with miR-223. Serum miR-132 and miR-223 levels were significantly higher in the survivor group than in the deceased group (P<0.001). The sensitivity and specificity for the prognosis of SIC were 85.96 and 65.22% for miR-132 combined with miR-223. Serum miR-132 and miR-223 were negatively correlated with serum CK-MB, cTnI, TNF-α, and IL-6 (P<0.001). miR-132 combined with miR-223 can be used for early diagnosis and prognostic evaluation of SIC, and the two are correlated with CK-MB, cTnI, TNF-α, and IL-6.

Advances in Cardiotoxicity Induced by Altered Mitochondrial Dynamics and Mitophagy

Mitochondria are the most abundant organelles in cardiac cells, and are essential to maintain the normal cardiac function, which requires mitochondrial dynamics and mitophagy to ensure the stability of mitochondrial quantity and quality. When mitochondria are affected by continuous injury factors, the balance between mitochondrial dynamics and mitophagy is broken. Aging and damaged mitochondria cannot be completely removed in cardiac cells, resulting in energy supply disorder and accumulation of toxic substances in cardiac cells, resulting in cardiac damage and cardiotoxicity. This paper summarizes the specific underlying mechanisms by which various adverse factors interfere with mitochondrial dynamics and mitophagy to produce cardiotoxicity and emphasizes the crucial role of oxidative stress in mitophagy. This review aims to provide fresh ideas for the prevention and treatment of cardiotoxicity induced by altered mitochondrial dynamics and mitophagy.

Induction and deduction in sepsis-induced cardiomyopathy: five typical categories

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. The heart is one of the most important oxygen delivery organs, and dysfunction significantly increases the mortality of the body. Hence, the heart has been studied in sepsis for over half a century. However, the definition of sepsis-induced cardiomyopathy is not unified yet, and the conventional conception seems outdated: left ventricular systolic dysfunction (LVSD) along with enlargement of the left ventricle, recovering in 7 to 10 days. With the application of echocardiography in intensive care units, not only LVSD but also left ventricular diastolic dysfunction, right ventricular dysfunction, and even diffuse ventricular dysfunction have been seen. The recognition of sepsis-induced cardiomyopathy is gradually becoming complete, although our understanding of it is not deep, which has made the diagnosis and treatment stagnate. In this review, we summarize the research on sepsis-induced cardiomyopathy. Women and young people with septic cardiomyopathy are more likely to have LVSD, which may have the same mechanism as stress cardiomyopathy. Elderly people with ischemic cardiomyopathy and hypertension tend to have left ventricular diastolic dysfunction. Patients with mechanical ventilation, acute respiratory distress syndrome or other complications of increased right ventricular afterload mostly have right ventricular dysfunction. Diffuse cardiac dysfunction has also been shown in some studies; patients with mixed or co-existing cardiac dysfunction are more common, theoretically. Thus, understanding the pathophysiology of sepsis-induced cardiomyopathy from the perspective of critical care echocardiography is essential.

Septic Cardiomyopathy: From Basics to Management Choices

Septic cardiomyopathy (SCM) is increasingly recognized as a potential complication of septic shock; it is understood to be a reversible left ventricular systolic dysfunction. The presence of SCM in septic shock, in previous studies, infer a poorer prognosis as it significantly increases the mortality rate of patients to 70%-90% and its incidence varies from 18% to 40% of septic shock patients. The pathogenesis is unclear, but believed to be a combination of bacterial toxins, cytokines, nitric oxide, and cardiac mitochondrial dysfunction, that depresses intrinsic cardiac contractility. The presence of SCM can be diagnosed in patients using a bedside transthoracic echocardiogram which typically shows left ventricular ejection fraction <45% and right ventricular dilatation. For management, levosimendan provides a good hemodynamic response without increasing cardiac oxygen demand when compared to dobutamine, while more invasive techniques such as extracorporeal membrane oxygenation, and intra-aortic balloon pulsation are being explored as well as potential rescue strategies for patients with severe SCM.