Left Ventricular Unloading Using an Impella CP Improves Coronary Flow and Infarct Zone Perfusion in Ischemic Heart Failure

Mechanical circulatory support reduces renal sympathetic nerve activity in an ovine model of acute myocardial infarction

PURPOSE

The use of circulatory assist devices has been shown to improve glomerular filtration rate and reduce the incidence of acute kidney injury in patients following acute cardiac pathology. However, the mechanisms of improvement in kidney function are not clear. We tested the hypothesis that mechanical circulatory support would result in a decrease in directly recorded renal sympathetic nerve activity (RSNA) and mediate the improvement in renal blood flow (RBF) in a setting of acute myocardial infarction (AMI)-induced left ventricular systolic dysfunction.

METHODS

An anaesthetized ovine model was used to induce AMI (n = 8) using injections of microspheres into the left coronary artery in one group. The second group did not undergo embolization (n = 6). The effects of mechanical circulatory support using the Impella CP on directly recorded renal sympathetic nerve activity were examined in these two groups of animals.

RESULTS

Injection of microspheres resulted in a drop in mean arterial pressure (MAP) of 21 ± 4 mmHg compared to baseline values (p < 0.05; n = 8). This was associated with a 67% increase in renal sympathetic nerve activity (RSNA; from 16 ± 5 to 21 ± 5 spikes/s; p < 0.05; n = 7). Impella CP support significantly increased MAP by 13 ± 1.5 mmHg at pump level 8 (p < 0.05) in the AMI group. Incremental pump support resulted in a significant decrease in RSNA (p < 0.05) in both groups. At pump level P8 in the AMI group, RSNA was decreased by 21 ± 5.5% compared to pump level P0 when the pump was not on.

CONCLUSION

Our data indicate that the improvement in kidney function following mechanical circulatory support may be mediated in part by renal sympathoinhibition.

Animal Models for Mechanical Circulatory Support: A Research Review

Heart failure is a clinical syndrome that has become a leading public health problem worldwide. Globally, nearly 64 million individuals are currently affected by heart failure, causing considerable medical, financial, and social challenges. One therapeutic option for patients with advanced heart failure is mechanical circulatory support (MCS) which is widely used for short-term or long-term management. MCS with various ventricular assist devices (VADs) has gained traction in end-stage heart failure treatment as a bridge-to-recovery, -decision, -transplant or -destination therapy. Due to limitations in studying VADs in humans, animal studies have substantially contributed to the development and advancement of MCS devices. Large animals have provided an avenue for developing and testing new VADs and improving surgical strategies for VAD implantation and for evaluating the effects and complications of MCS on hemodynamics and organ function. VAD modeling by utilizing rodents and small animals has been successfully implemented for investigating molecular mechanisms of cardiac unloading after the implantation of MCS. This review will cover the animal research that has resulted in significant advances in the development of MCS devices and the therapeutic care of advanced heart failure.

Pearls and Pitfalls of Epicardial Echocardiography for Implantation of Impella CP Devices in Ovine Models

The Impella CP is a percutaneously inserted temporary left ventricular assist device used in clinical practice and in translational research into cardiogenic shock, perioperative cardiac surgery, acute cardiac failure and mechanical circulatory support. Fluoroscopic guidance is usually used for insertion of an Impella, thus limiting insertion to within catheterization laboratories. Transthoracic, transoesophageal and intracardiac echocardiography have been reported to guide Impella CP implantation with identified specific limitations stemming from the surgical, anatomical and equipment factors. We conducted translational prospective descriptive feasibility investigation as a part of two other hemodynamic Impella studies. It showed the successful application of epicardial echocardiographic scanning for implantation of Impella CP devices in ovine models, from which details of the technique and identified pitfalls are described with practical solutions for future investigators and clinicians. Many described findings are relevant to any other echocardiographic techniques when adequate imaging of the Impella and relevant anatomical structures is achievable.

Contemporary optimal therapeutic strategy with escalation/de-escalation of temporary mechanical circulatory support in patients with cardiogenic shock and advanced heart failure in Japan

The utilization of temporary mechanical circulatory support (MCS) in the management of cardiogenic shock is experiencing a notable surge. Acute myocardial infarction remains the predominant etiology of cardiogenic shock, followed by heart failure. Recent findings from the DanGer Shock trial indicate that the percutaneous micro-axial flow pump support, in conjunction with standard care, significantly reduced 6-month mortality in patients with acute myocardial infarction-related cardiogenic shock compared to those receiving standard care alone. However, real-world registry data reveal that the 30-day mortality among patients with acute myocardial infarction-related cardiogenic shock, who received concomitant veno-arterial extracorporeal membrane oxygenation support along with micro-axial flow pump, remain suboptimal. The persistent challenge in the field is how to incorporate, escalate, and de-escalate these temporary MCS to further improve clinical outcomes in such clinical scenarios. This review aims to elucidate the current practices surrounding the escalation and de-escalation of temporary MCS in real-world clinical settings and proposes considerations for future advancements in this critical area.

Therapeutic potential of human induced pluripotent stem cell-derived cardiac tissue in an ischemic model with unloaded condition mimicking left ventricular assist device

OBJECTIVE

This study aimed to explore the therapeutic potential of human induced pluripotent stem cell (hiPSC)-derived cardiac tissues (HiCTs) in the emerging approach of bridge to recovery for severe heart failure with ventricular assist devices. We used a rat model of heterotopic heart transplantation (HTx) to mimic ventricular assist device support and heart unloading.

METHODS

HiCTs were created by inserting gelatin hydrogel microspheres between cell sheets made from hiPSC-derived cardiovascular cells. Male athymic nude rats underwent myocardial infarction (MI) and were divided into the following groups: MI (loaded, untreated control), MI + HTx (unloaded, untreated control), MI + HTx + HiCT (unloaded, treated), and MI + HiCT (loaded, treated). HiCTs were placed on the epicardium of the heart in treated groups. We evaluated HiCT engraftment, fibrosis, and neovascularization using histologic analysis.

RESULTS

After 4 weeks, HiCTs successfully engrafted in 5 of 6 rats in the MI + HTx + HiCT group (83.3%). The engrafted HiCT area was greater under unloaded conditions (MI + HTx + HiCT) than loaded conditions (MI + HiCT) (P < .05). MI + HTx + HiCT had a significantly smaller infarct area compared with MI and MI + HTx. The MI + HTx + MiCT group exhibited greater vascular density in the border zone than MI and MI + HTx. HiCT treatment suppressed cardiomyocyte atrophy due to left ventricular unloading (P = .001). The protein level of muscle-specific RING finger 1, an atrophy-related ubiquitin ligase, was lower in the MI + HTx + HiCT group than in MI + HTx (P = .036).

CONCLUSIONS

Transplanting HiCTs into ischemic hearts under unloaded conditions promoted engraftment, neovascularization, attenuated infarct remodeling, and suppressed myocyte atrophy. These results suggest that HiCT treatment could contribute to future advancements in bridge to recovery.

Restoration of Epicardial Blood Flow After Left Ventricular Unloading With the Impella CP Heart Pump in a Patient With STEMI Treated With Surgical Revascularization

Left main occlusion presenting as ST-segment elevation myocardial infarction is an exceedingly morbid condition. This article reports a case of cardiac arrest in a patient after a treadmill stress test. Coronary angiography revealed 100% occlusion of the left main coronary artery. Left ventricular unloading with the Impella CP heart pump (ABIOMED/Johnson & Johnson MedTech) was used, after which epicardial blood flow was restored without angioplasty. The patient underwent surgical revascularization. Despite a prolonged revascularization time, there was no evidence of severe myocardial injury postoperatively.

Treatment and Care of Patients with ST-Segment Elevation Myocardial Infarction-What Challenges Remain after Three Decades of Primary Percutaneous Coronary Intervention?

Primary percutaneous coronary intervention (pPCI) has revolutionized the prognosis of ST-segment elevation myocardial infarction (STEMI) and is the gold standard treatment. As a result of its success, the number of pPCI centres has expanded worldwide. Despite decades of advancements, clinical outcomes in STEMI patients have plateaued. Out-of-hospital cardiac arrest and cardiogenic shock remain a major cause of high in-hospital mortality, whilst the growing burden of heart failure in long-term STEMI survivors presents a growing problem. Many elements aiming to optimize STEMI treatment are still subject to debate or lack sufficient evidence. This review provides an overview of the most contentious current issues in pPCI in STEMI patients, with an emphasis on unresolved questions and persistent challenges.

Reduction of left ventricular diastolic pressure as a key regulator of infarct coronary flow under mechanical left ventricular support

Restoring ischaemic myocardial tissue perfusion is crucial for minimizing infarct size. Acute mechanical left ventricular (LV) support has been suggested to improve infarct tissue perfusion. However, its regulatory mechanism remains unclear. We investigated the physiological mechanisms in six Yorkshire pigs, which were subjected to 90-min balloon occlusion of the left anterior descending artery. During the acute reperfusion phase, LV support using an Impella heart pump was initiated. LV pressure, coronary flow and pressure of the infarct artery were simultaneously recorded to evaluate the impact of LV support on coronary physiology. Coronary wave intensity was calculated to understand the forces regulating coronary flow. Significant increases in coronary flow velocity and its area under the curve were found after mechanical LV support. Among the coronary flow-regulating factors, coronary pressure was increased mainly during the late diastolic phase with less pulsatility. Meanwhile, LV pressure was reduced throughout diastole resulting in significant and consistent elevation of coronary driving pressure. Interestingly, the duration of diastole was prolonged with LV support. In the wave intensity analysis, the duration between backward suction and pushing waves was extended, indicating that earlier myocardial relaxation and delayed contraction contributed to the extension of diastole. In conclusion, mechanical LV support increases infarct coronary flow by extending diastole and augmenting coronary driving pressure. These changes were mainly driven by reduced LV diastolic pressure, indicating that the key regulator of coronary flow under mechanical LV support is downstream of the coronary artery, rather than upstream. Our study highlights the importance of LV diastolic pressure in infarct coronary flow regulation. KEY POINTS: Restoring ischaemic myocardial tissue perfusion is crucial for minimizing infarct size. Although mechanical left ventricular (LV) support has been suggested to improve infarct coronary flow, its specific mechanism remains to be clarified. LV support reduced LV pressure, and elevated coronary pressure during the late diastolic phase, resulting in high coronary driving pressure. This study demonstrated for the first time that mechanical LV support extends diastolic phase, leading to increased infarct coronary flow. Future studies should evaluate the correlation between improved infarct coronary flow and resulting infarct size.

Intra-aortic balloon pump versus percutaneous Impella© in emergency revascularisation for myocardial infarction and cardiogenic shock: systematic review

OBJECTIVES

Mortality rates in patients with acute myocardial infarction and cardiogenic shock (AMI-CS) remain persistently high despite advances over the past decade in percutaneous mechanical circulatory support. This systematic review aims to analyse the existing literature to compare mortality outcomes in patients mechanically supported by intra-aortic balloon pump or percutaneous Impella 2.5/CP© for AMI-CS undergoing emergency revascularisation.

METHODS

The following MeSH terms were applied to the databases Ovid Medline, Ovid Embase, Cochrane and Web of Science: 'Intra-aortic balloon pump', 'Impella', 'Cardiogenic shock', 'Myocardial Infarction' and 'Mortality'. This yielded 2643 studies. Using predefined inclusion and exclusion criteria, the studies were initially screened by title and abstract before full text analysis.

RESULTS

Fourteen studies met eligibility criteria: two randomised controlled trials (RCTs) and 12 observational studies. Data from a total of 21,006 patients were included across the studies. Notably, one study claimed reduced mortality with IABP versus control, and one study concluded that Impella© improved survival rates over the IABP. The average 30-day all-cause mortality in patients supported by IABP was 38.1%, 54.3% in Impella© groups and 39.4% in control groups.

CONCLUSION

AMI-CS presents an important cohort of patients in whom conducting RCTs is difficult. As a result, the literature is limited. Analysis of the available literature suggests that there is insufficient evidence to support superior survival in those supported by IABP or Impella© when compared to control despite suggestions that the Impella© offers superior haemodynamic support. Limitations of the studies have been discussed to outline suggestions for future research.

Infarct Size Reduction in an Anterior ST-Elevation Myocardial Infarction Following "Optimized" Supersaturated Oxygen Therapy

This comprehensive case report documents the treatment of a 37-year-old female patient who presented with anterior ST-elevation myocardial infarction (STEMI). The patient underwent percutaneous coronary intervention (PCI), followed by an innovative therapy - optimized supersaturated oxygen therapy (SSO2). This therapy was chosen due to its potential to enhance myocardial salvage, particularly in severe MI cases like the patient. The report meticulously details the patient's clinical course, including the diagnostic procedures and the rationale behind opting for SSO2 therapy. It highlights the significant improvements observed post-therapy: enhanced left ventricular (LV) function and a remarkable reduction in the size of the LV apical aneurysm. These outcomes suggest a direct benefit of SSO2 in reducing myocardial damage. Finally, the report discusses the broader implications of these findings. It underscores the potential of optimized SSO2 therapy in clinical settings, particularly for patients with anterior MI. The case exemplifies how advanced therapeutic interventions like SSO2 can play a pivotal role in improving clinical outcomes post-MI, thereby advocating for its consideration in similar clinical scenarios.

Acute Heart Failure and Coronary Blood Flow in ST-Elevation Myocardial Infarction Patients Undergoing Primary Percutaneous Coronary Intervention: An Observational Cohort Study

Background and objective The Global Registry of Acute Coronary Events (GRACE) study showed poor outcomes in ST-elevation myocardial infarction (STEMI) patients with acute heart failure (AHF) at hospital admission in terms of increased in-hospital and six-month mortality and readmission rates. In this study, we aimed to examine the effects of AHF at the time of admission on the coronary thrombus burden and post-primary percutaneous coronary intervention (PPCI) coronary flow among STEMI patients. Methods We conducted a cohort study involving 210 consecutive STEMI patients who presented to a single PPCI centre between June 2016 and January 2017. We classified them into two groups based on their Killip class at the time of presentation to the emergency department: no heart failure (NHF) and AHF groups. The primary outcome was the incidence of Thrombolysis In Myocardial Infarction (TIMI) flow grade of less than 3 in the stented coronary artery in the absence of mechanical obstruction or dissection (also known as no-reflow). The secondary outcome was the presence of a heavy thrombus burden (TIMI grade 4 or 5) at the time of angiography. Results The AHF group had a significantly higher incidence of no-reflow than the NHF group (25% vs. 8.4%, p=0.019). However, the prevalence of heavy thrombus burden did not differ significantly between the two groups (50% in the AHF group vs. 43.16% in the NHF group, p=0.557). The multivariable logistic regression analysis showed that AHF was an independent predictor of no-reflow in STEMI patients post-PPCI [Odds ratio (OR): 3.59, 95% confidence interval (CI): 1.09-11.83, p=0.035]. Conclusion Based on our findings, AHF is associated with an increased risk of no-reflow in STEMI patients post-PPCI, irrespective of the coronary thrombus load.

DCM Support: cell therapy and circulatory support for dilated cardiomyopathy patients with severe ventricular impairment

AIMS

The DCM Support trial (NCT03572660) uses a percutaneous circulatory support device (Impella CP, Abiomed, Danvers, MA, USA) to improve the safety of an intracoronary cell infusion procedure in patients with dilated cardiomyopathy (DCM) and a severely reduced left ventricular ejection fraction (LVEF).

METHODS AND RESULTS

DCM Support is a single-site, single-arm Phase II trial enrolling 20 symptomatic DCM patients with an LVEF ≤ 35% despite optimal medical and device therapy. After 5 days of granulocyte colony-stimulating factor therapy and a subsequent bone marrow aspiration, patients undergo an intracoronary infusion of autologous bone-marrow-derived mononuclear cells. The Impella CP device is used to provide haemodynamic support during the infusion procedure. The trial's primary endpoint is change in LVEF from baseline at 3 months. Secondary efficacy endpoints are change in LVEF from baseline at 12 months, and change in exercise capacity, New York Heart Association class, quality of life, and N-terminal pro-B-type natriuretic peptide levels from baseline at 3 and 12 months. Safety endpoints include procedural safety and major adverse cardiac events at 3 and 12 months.

CONCLUSIONS

This is the first trial to assess the safety and efficacy of cytokine and autologous intracoronary cell therapy with a procedural circulatory support device for patients with severe left ventricular impairment. This novel combination may allow us to target a patient population most at need of this therapy.

IABP versus Impella Support in Cardiogenic Shock: “In Silico” Study

Cardiogenic shock (CS) is part of a clinical syndrome consisting of acute left ventricular failure causing severe hypotension leading to inadequate organ and tissue perfusion. The most commonly used devices to support patients affected by CS are Intra-Aortic Balloon Pump (IABP), Impella 2.5 pump and Extracorporeal Membrane Oxygenation. The aim of this study is the comparison between Impella and IABP using CARDIOSIM© software simulator of the cardiovascular system. The results of the simulations included baseline conditions from a virtual patient in CS followed by IABP assistance in synchronised mode with different driving and vacuum pressures. Subsequently, the same baseline conditions were supported by the Impella 2.5 with different rotational speeds. The percentage variation with respect to baseline conditions was calculated for haemodynamic and energetic variables during IABP and Impella assistance. The Impella pump driven with a rotational speed of 50,000 rpm increased the total flow by 4.36% with a reduction in left ventricular end-diastolic volume (LVEDV) by ≅15% to ≅30%. A reduction in left ventricular end systolic volume (LVESV) by ≅10% to ≅18% (≅12% to ≅33%) was observed with IABP (Impella) assistance. The simulation outcome suggests that assistance with the Impella device leads to higher reduction in LVESV, LVEDV, left ventricular external work and left atrial pressure-volume loop area compared to IABP support.

Device-Based Approaches Targeting Cardioprotection in Myocardial Infarction: The Expanding Armamentarium of Innovative Strategies

Coronary reperfusion therapy has played a pivotal role for reducing mortality and heart failure after acute myocardial infarction. Although several adjunctive approaches have been studied for reducing infarct size further, both ischemia-reperfusion injury and microvascular obstruction are still major contributors to both early and late clinical events after acute myocardial infarction. The progress in the field of cardioprotection has found several promising proof-of-concept preclinical studies. However, translation from bench to bedside has not been very successful. This comprehensive review discusses the importance of infarct size as a driver of clinical outcomes post-acute myocardial infarction and summarizes recent novel device-based approaches for infarct size reduction. Device-based interventions including mechanical cardiac unloading, myocardial cooling, coronary sinus interventions, supersaturated oxygen therapy, and vagal stimulation are discussed. Many of these approaches can modify ischemic myocardial biology before reperfusion and offer unique opportunities to target ischemia-reperfusion injury.

Analogue Mean Systemic Filling Pressure: a New Volume Management Approach During Percutaneous Left Ventricular Assist Device Therapy

The absence of an accepted gold standard to estimate volume status is an obstacle for optimal management of left ventricular assist devices (LVADs). The applicability of the analogue mean systemic filling pressure (Pmsa) as a surrogate of the mean circulatory pressure to estimate volume status for patients with LVADs has not been investigated. Variability of flows generated by the Impella CP, a temporary LVAD, should have no physiological impact on fluid status. This translational interventional ovine study demonstrated that Pmsa did not change with variable circulatory flows induced by a continuous flow LVAD (the average dynamic increase in Pmsa of 0.20 ± 0.95 mmHg from zero to maximal Impella flow was not significant (p = 0.68)), confirming applicability of the human Pmsa equation for an ovine LVAD model. The study opens new directions for future translational and human investigations of fluid management using Pmsa for patients with temporary LVADs.

Procedural results and in-hospital outcomes of percutaneous coronary intervention for chronic total occlusion in patients with reduced left ventricular ejection fraction: Sub-analysis of the Japanese CTO-PCI Expert Registry

OBJECTIVES

To evaluate the procedural results and in-hospital outcomes of percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) in patients with reduced left ventricular ejection fraction (LVEF).

BACKGROUND

While the technical success of general CTO-PCI has improved, CTO-PCI patients with reduced LVEF remain at high-risk for adverse events.

METHODS

The data of 820 patients with LVEF ≤ 35% (Group 1), 1816 patients with LVEF = 35%-50% (Group 2), and 5503 patients with LVEF ≥ 50% (Group 3), registered in the Japanese CTO-PCI Expert Registry from January 2014 to December 2019, were retrospectively analyzed. The primary endpoint was in-hospital major adverse cardiac or cerebrovascular events (MACCEs), including death, myocardial infarction, stent thrombosis, stroke, and emergent revascularization. Secondary endpoints included procedural details, guidewire success, and technical success.

RESULTS

There were no differences in guidewire and technical success rates between the groups. In-hospital MACCEs was significantly higher in Group 1 (Group 1 vs. Group 2 vs. Group 3: 3.4% vs. 1.7% vs. 1.5%, p = 0.001) and was especially driven by death (1.3% vs. 0.3% vs. 0.1%, p < 0.001) and stroke (0.7% vs. 0.2% vs. 0.2%, p = 0.007). Multivariate analysis showed that LVEF ≤ 35% (odds ratio [OR]; 1.58, 95% confidence interval [CI]; 1.04-2.41, p = 0.03) and New York Heart Association (NYHA) class ≥ 3 (OR; 2.01, 95% CI; 1.03-3.93, p = 0.04) were predictors of in-hospital MACCEs.

CONCLUSIONS

In-hospital MACCEs were significantly higher in patients with LVEF ≤ 35%. LVEF ≤;35% and NYHA class ≥ 3 were predictors of in-hospital MACCEs after CTO-PCI.

Risk Stratification by Coronary Perfusion Pressure in Left Ventricular Systolic Dysfunction Patients Undergoing Revascularization: A Propensity Score Matching Analysis

Background

Coronary perfusion pressure (CPP) and coronary artery stenosis are responsible for myocardial perfusion. However, how CPP-related survival outcome affects revascularization is unclear.

Objective

The aim of this study is to investigate the prognostic role of CPP in patients with left ventricular systolic dysfunction (LVSD) undergoing percutaneous coronary intervention (PCI) with complete revascularization (CR) or reasonable incomplete revascularization (RIR).

Methods

We retrospectively screened 6,076 consecutive patients in a registry. The residual synergy between percutaneous coronary intervention with Taxus and cardiac surgery (SYNTAX) score (rSS) was used to define CR (rSS = 0) and RIR (0<rSS≤8). Propensity score matching was performed to reduce bias between RIR and CR. The primary endpoint was all-cause mortality.

Results

In total, 816 patients with LVSD who underwent CR or RIR were enrolled. After a mean follow-up of 4.6 years, 134 patients died. Both CPP and RIR independently predicted mortality in the total population. After 1:1 matching, 175 pairs of RIR and CR were found in patients with CPP > 42 mmHg. Moreover, 101 pairs of RIR and CR were present in patients with CPP ≤ 42 mmHg. In patients with CPP > 42 mmHg, RIR was not significantly different from CR in long-term mortality [hazard ratio (HR) 1.20; 95% confidence interval (CI):0.70–2.07; p = 0.513]; However, in patients with CPP≤42 mmHg, RIR had a significantly higher mortality risk than CR (HR 2.39; 95% CI: 1.27–4.50; p = 0.007).

Conclusions

The CPP had a risk stratification role in selecting different revascularization strategies in patients with LVSD. When patients with LVSD had CPP > 42 mmHg, RIR was equivalent to CR in survival. However, when patients with LVSD had CPP ≤ 42 mmHg, RIR had a significantly higher mortality risk than CR.

Intracoronary Application of Super-Saturated Oxygen to Reduce Infarct Size Following Myocardial Infarction

Optimal medical therapy for secondary prevention following acute myocardial infarction reduces non-fatal ischaemic events. Intensive antithrombotic or lipid-lowering approaches have failed to significantly lower mortality. In the past, reduction of infarct size in patients undergoing primary percutaneous revascularisation for acute myocardial infarction had been considered as a surrogate outcome marker. However, infarct size measured by magnetic resonance imaging or SPECT is strongly associated with all-cause mortality and hospitalization for heart failure within the first year after an acute myocardial infarction. Intracoronary administration of super-saturated oxygen (SSO₂) immediately after revascularisation is an approach that can be used to reduce infarct size and, therefore, improve cardiovascular outcome in patients with acute myocardial infarction. In this article, we describe the modulation of pathophysiology by SSO₂, review the existing trial data and present our first impressions with the technique in real clinical practice.

Impaired Diastolic Function Predicts Improved Ischemic Myocardial Flow by Mechanical Left Ventricular Unloading in a Swine Model of Ischemic Heart Failure

Background: Impact of mechanical left ventricular (LV) unloading on myocardial tissue perfusion and its regulating factors remain unclear. This study was conducted to elucidate the predictors of regional blood flow (RBF) improvement by mechanical LV unloading. Materials and Methods: One to four weeks after percutaneous induction of myocardial infarction (MI), Yorkshire pigs (n = 15) underwent mechanical LV unloading using Impella CP. Hemodynamic parameters were collected prior to LV unloading. RBF in infarct, border and remote myocardium were measured by fluorescent microsphere injections before and 120 min after LV unloading. Results: RBF showed variable responses to mechanical LV unloading. While infarct RBF improved in general (0.33 ± 0.13 to 0.42 ± 0.19 mL/min/g, p = 0.06), there were a few pigs that showed little improvement. Meanwhile, there were no clear trends in the border (1.07 ± 0.47 to 1.02 ± 0.65 mL/min/g, p = 0.73) and remote myocardial RBF (1.25 ± 0.52 to 1.23 ± 0.68 mL/min/g, p = 0.85). In the simple linear regression analysis, cardiac output, mean pulmonary arterial wedge pressure, mean left atrial pressure, minimum LV pressure, end-diastolic LV pressure, maximum dP/dt, slope of end-diastolic pressure-volume relationship (EDPVR) and end-diastolic wall stress were significantly associated with % change of infarct RBF. In the multiple regression model, slope of EDPVR and maximum dP/dt remained as independent predictors of infarct RBF change. Conclusion: Steeper EDPVR and lower maximum dP/dt were associated with increased blood perfusion in the infarct area after LV unloading. Our data suggests mechanical LV unloading is more beneficial in post-MI patients with high diastolic pressure associated with increased LV stiffness and in those with worse cardiac contractility.

Mitochondrial Metabolism in Myocardial Remodeling and Mechanical Unloading: Implications for Ischemic Heart Disease

Ischemic heart disease refers to myocardial degeneration, necrosis, and fibrosis caused by coronary artery disease. It can lead to severe left ventricular dysfunction (LVEF ≤ 35–40%) and is a major cause of heart failure (HF). In each contraction, myocardium is subjected to a variety of mechanical forces, such as stretch, afterload, and shear stress, and these mechanical stresses are clinically associated with myocardial remodeling and, eventually, cardiac outcomes. Mitochondria produce 90% of ATP in the heart and participate in metabolic pathways that regulate the balance of glucose and fatty acid oxidative phosphorylation. However, altered energetics and metabolic reprogramming are proved to aggravate HF development and progression by disturbing substrate utilization. This review briefly summarizes the current insights into the adaptations of cardiomyocytes to mechanical stimuli and underlying mechanisms in ischemic heart disease, with focusing on mitochondrial metabolism. We also discuss how mechanical circulatory support (MCS) alters myocardial energy metabolism and affects the detrimental metabolic adaptations of the dysfunctional myocardium.

Current Landscape of Temporary Percutaneous Mechanical Circulatory Support Technology

Mechanical circulatory support devices provide hemodynamic support to patients who present with cardiogenic shock. These devices work using different mechanisms to provide univentricular or biventricular support. There is a growing body of evidence supporting use of these devices as a goal for cardiac recovery or as a bridge to definitive therapy, but definitive, well-powered studies are still needed. Mechanical circulatory support devices are increasingly used using shock team and protocols, which can help clinicians in decision making, balancing operator and institutional experience and expertise. The aim of this article is to review commercially available mechanical circulatory support devices, their profiles and mechanisms of action, and the evidence available regarding their use.

Comparison of Mechanical Support with Impella or Extracorporeal Life Support in Post-Cardiac Arrest Cardiogenic Shock: A Propensity Scoring Matching Analysis

Our aim was to compare the outcomes of Impella with extracorporeal life support (ECLS) in patients with post-cardiac arrest cardiogenic shock (CS) complicating acute myocardial infarction (AMI). This was a retrospective study of patients resuscitated from out of hospital cardiac arrest (OHCA) with post-cardiac arrest CS following AMI (May 2015 to May 2020). Patients were supported either with Impella 2.5/CP or ECLS. Outcomes were compared using propensity score-matched analysis to account for differences in baseline characteristics between groups. 159 patients were included (Impella, n = 105; ECLS, n = 54). Hospital and 12-month survival rates were comparable in the Impella and the ECLS groups (p = 0.16 and p = 0.3, respectively). After adjustment for baseline differences, both groups demonstrated comparable hospital and 12-month survival (p = 0.36 and p = 0.64, respectively). Impella patients had a significantly greater left ventricle ejection-fraction (LVEF) improvement at 96 h (p < 0.01 vs. p = 0.44 in ECLS) and significantly fewer device-associated complications than ECLS patients (15.2% versus 35.2%, p < 0.01 for relevant access site bleeding, 7.6% versus 20.4%, p = 0.04 for limb ischemia needing intervention). In subgroup analyses, Impella was associated with better survival in patients with lower-risk features (lactate < 8.6 mmol/L, time from collapse to return of spontaneous circulation < 28 min, vasoactive score < 46 and Horowitz index > 182). In conclusion, the use of Impella 2.5/CP or ECLS in post-cardiac arrest CS after AMI was associated with comparable adjusted hospital and 12-month survival. Impella patients had a greater LVEF improvement than ECLS patients. Device-related access-site complications occurred more frequently in patients with ECLS than Impella support.

Long-term 5-year outcome of the randomized IMPRESS in severe shock trial: percutaneous mechanical circulatory support vs. intra-aortic balloon pump in cardiogenic shock after acute myocardial infarction

AIMS

To assess differences in long-term outcome and functional status of patients with cardiogenic shock (CS) treated by percutaneous mechanical circulatory support (pMCS) and intra-aortic balloon pump (IABP).

METHODS AND RESULTS

Long-term follow-up of the multicentre, randomized IMPRESS in Severe Shock trial (NTR3450) was performed 5-year after initial randomization. Between 2012 and 2015, a total of 48 patients with severe CS from acute myocardial infarction (AMI) with ST-segment elevation undergoing immediate revascularization were randomized to pMCS by Impella CP (n = 24) or IABP (n = 24). For the 5-year assessment, all-cause mortality, functional status, and occurrence of major adverse cardiac and cerebrovascular event (MACCE) were assessed. MACCE consisted of death, myocardial re-infarction, repeat percutaneous coronary intervention, coronary artery bypass grafting, and stroke. Five-year mortality was 50% (n = 12/24) in pMCS patients and 63% (n = 15/24) in IABP patients (relative risk 0.87, 95% confidence interval 0.47-1.59, P = 0.65). MACCE occurred in 12/24 (50%) of the pMCS patients vs. 19/24 (79%) of the IABP patients (P = 0.07). All survivors except for one were in New York Heart Association Class I/II [pMCS n = 10 (91%) and IABP n = 7 (100%), P = 1.00] and none of the patients had residual angina. There were no differences in left ventricular ejection fraction between the groups (pMCS 52 ± 11% vs. IABP 48 ± 10%, P = 0.53).

CONCLUSIONS

In this explorative randomized trial of patients with severe CS after AMI, there was no difference in long-term 5-year mortality between pMCS and IABP-treated patients, supporting previously published short-term data and in accordance with other long-term CS trials.

Early Experience with the HeartMate Percutaneous Heart Pump from the SHIELD II Trial

The HeartMate Percutaneous Heart Pump (PHP) is a novel circulatory support catheter delivering a self-expanding 24 French impeller across the aortic valve. The SHIELD II trial compares outcomes among heart failure patients undergoing high-risk percutaneous coronary intervention (HR-PCI) with the PHP versus Impella systems. The trial was halted in 2017 due to device malfunctions. We aimed to describe procedural, hemodynamic, and clinical outcomes among HR-PCI patients treated with PHP as part of the SHIELD II trial roll-in phase. Procedural, hemodynamic, and 90 day outcomes were assessed among patients undergoing HR-PCI with a left ventricular ejection fraction ≤35% and last patent coronary conduit, unprotected left main disease, or significant three vessel disease. The primary endpoint was the 90 day composite of cardiovascular death, myocardial infarction, stroke, repeat revascularization, major bleeding, new/worsening aortic regurgitation, and severe hypotension. Among 75 roll-in phase patients, PHP support duration was 101 ± 53 minutes with 2.5 ± 1.4 coronary lesions treated per patient. Compared with predevice values, the PHP system increased cardiac power and mean arterial pressure. Maximum recorded device flows were 0.4-6.2 L/minute with 26% (n = 19/73) and 9.6% (n = 7/73) of patients achieving peak flows above 3.5 or 5.0 L/minute, respectively. Five PHP device malfunction events (6.7%) were observed. At 90 days, the composite endpoint occurred in 24.3% (18/74) of patients. Early PHP experience demonstrated successful device performance in the majority of enrolled patients; however, unexpected malfunctions led to device revision. Completion of the SHIELD II trial will be required to confirm the safety and efficacy of this iteration of the PHP system in HR-PCI.

Left Ventricular Assist Devices for Acute Myocardial Infarct Size Reduction: Meta-analysis

We conducted a meta-analysis of preclinical studies that tested left ventricular assist device (LVAD) therapy for reducing myocardial infarct size in experimental acute myocardial infarction (AMI). Twenty-six articles were included with a total of 488 experimental animal subjects. The meta-analysis showed that infarct size was significantly decreased by LVAD support compared to control animals (SDM, - 2.19; 95% CI, - 2.70 to - 1.69; P < 0.001). The meta-regression analysis demonstrated a high degree of heterogeneity associated with time from coronary artery occlusion to LVAD support, which correlated positively with infarct size. Subgroup analysis suggested smaller infarct size in LVAD therapies that withdrew blood from left heart than those from right heart. The proportion of left ventricular support relative to total cardiac output was positively correlated with infarct size reduction in Impella studies. Thus, early initiation of LVAD after ischemia and effective left ventricular venting may be important factors to reduce infarct size in AMI.

Left ventricular unloading and the role of ECpella

The main reason for the emergency implantation of venoarterial extracorporeal membrane oxygenation (VA-ECMO) is the restoration of adequate systemic perfusion, while protecting the failing heart and promoting myocardial recovery are equally important goals. Following initial haemodynamic stabilization and often the urgent revascularization of the culprit lesion, the clinical focus is then directed towards the most efficient strategy for cardioprotection. Frequent echocardiography measurements may help to estimate the degree of unwanted left ventricular (LV) overloading during VA-ECMO. Additionally, the estimation of high LV filling pressures by Doppler echocardiography or their (in-)direct measurement using a dedicated surgical left atrial pressure line and conventional pulmonary artery catheter in a wedge position or a pigtail catheter in the left ventricle can be performed. Mechanical overload of the left ventricle is the major adverse effect and an obvious mechanistic and prognostic challenge of contemporary ECMO care. Many efforts are under way to overcome this phenomenon by LV unloading, which was effectively achieved by the current combined approach using an axial decompression device, while novel technical developments and approaches are tested and urgently anticipated. The aim of this report is to introduce in depth pathophysiological background, current concepts, and future perspectives in LV unloading strategies.

A novel intra-ventricular assist device enhances cardiac performance in normal and acutely failing isolated porcine hearts

Background:

We recently demonstrated that a novel intra-ventricular membrane pump (IVMP) was able to increase the pump function of isolated beating porcine hearts. In follow-up, we now investigated the impact of the IVMP on myocardial oxygen consumption and total mechanical efficiency (TME) and assessed the effect of IVMP-support in acutely failing hearts.

Methods:

In 10 ex vivo beating porcine hearts, we studied hemodynamic parameters, as well as arterial and coronary venous oxygen content. We assessed cardiac power (CP), myocardial oxygen consumption (MVO₂), and TME (CP divided by MVO₂) under baseline conditions and during IVMP-support. Additionally, five isolated hearts were subjected to global hypoxia to investigate the effects of IVMP-support on CP under conditions of acute heart failure.

Results:

Under physiological conditions, baseline CP was 0.36 ± 0.10 W, which increased to 0.65 ± 0.16 W during IVMP-support (increase of 85% ± 24, p < 0.001). This was accompanied by an increase in MVO2 from 18.6 ± 6.2 ml/min at baseline, to 22.3 ± 5.0 ml/min during IVMP-support (+26 ± 31%, p = 0.005). As a result, TME (%) increased from 5.9 ± 1.2 to 8.8 ± 1.8 (50 ± 22% increase, p < 0.001). Acute hypoxia-induced cardiac pump failure reduced CP by 35 ± 6%, which was fully restored to baseline levels during IVMP-support in all hearts.

Conclusion:

IVMP-support improved mechanical efficiency under physiological conditions, as the marked increase in cardiac performance only resulted in a modest increase in oxygen consumption. Moreover, the IVMP rapidly restored cardiac performance under conditions of acute pump failure. These observations warrant further study, to evaluate the effects of IVMP-support in in vivo animal models of acute cardiac pump failure.

Timing of Impella implantation and outcomes in cardiogenic shock or high-risk percutaneous coronary revascularization

Objective

To evaluate the role of the microaxial percutaneous mechanical circulatory support device (Impella® pump) implantation pre‐percutaneous coronary intervention (PCI) versus during/after PCI in cardiogenic shock (CS) and high‐risk PCI populations.

Background

A better understanding of the safety and effectiveness of the Impella and the role of timing of this support initiation in specific clinical settings is of utmost clinical relevance.

Methods

A total of 365 patients treated with Impella 2.5/CP in the 17 centers of the IMP‐IT Registry were included. Through propensity‐score weighting (PSW) analysis, 1‐year clinical outcomes were assessed separately in CS and HR‐PCI patients, stratified by timing of Impella support.

Results

Pre‐procedural insertion was associated with an improvement in 1‐year survival in patients with CS due to acute myocardial infarction (AMI) treated with PCI (p = .04 before PSW, p = .009 after PSW) and HR‐PCI (p < .01 both before and after PSW). Among patients undergoing HR‐PCI, early Impella support was also associated with a lower rate of the composite of mortality, re‐hospitalization for heart failure, and need for left‐ventricular assist device/heart transplantation at 1‐year (p = .04 before PSW, p = .01 after PSW). Furthermore, Impella use during/after PCI was associated with an increased in‐hospital life‐threatening and severe bleeding among patients with AMI‐CS receiving PCI (7 vs. 16%, p = .1) and HR‐PCI (1 vs. 9%, p = .02).

Conclusions

Our findings suggested a survival benefit and reduced rates of major bleeding when a pre‐PCI Impella implantation instead of during‐after procedure was used in the setting of HR‐PCI and AMI‐CS.

Intensive care unit management of percutaneous mechanical circulatory supported patients: the role of imaging

The clinical management of patients on Impella support requires multimodality monitoring and imaging. Upon intensive care unit admission, echocardiography is essential to ensure correct pump positioning/guide repositioning, to monitor acute myocardial infarction/device-related cardiac complications and to evaluate baseline left and right ventricular function. Over time, the echocardiographic assessment of myocardial viability has become an essential target for guiding mechanical circulatory support escalation and long-term strategies. The recognition and grading of any valvular dysfunction and damage in Impella patients are challenging, as the device interferes with the colour Doppler signal, and the loading conditions of the left ventricle are modified by the pump. Valvular disease in such patients is often secondary, and correct identification is pivotal for future therapeutic strategies. The emerging use of newer techniques, including speckle-tracking echocardiography, is of increasing interest in the imaging of critically ill patients.

Early Impella Support in Postcardiac Arrest Cardiogenic Shock Complicating Acute Myocardial Infarction Improves Short- and Long-Term Survival

OBJECTIVES

Early mechanical circulatory support with Impella may improve survival outcomes in the setting of postcardiac arrest cardiogenic shock after out-of-hospital cardiac arrest complicating acute myocardial infarction. However, the optimal timing to initiate mechanical circulatory support in this particular setting remains unclear. Therefore, we aimed to compare survival outcomes of patients supported with Impella 2.5 before percutaneous coronary intervention (pre-PCI) with those supported after percutaneous coronary intervention (post-PCI).

DESIGN

Retrospective single-center study between September 2014 and December 2019 admitted to the Cardiac Arrest Center in Marburg, Germany.

PATIENTS

Out of 2,105 patients resuscitated from out-of-hospital cardiac arrest due to acute myocardial infarction with postcardiac arrest cardiogenic shock between September 2014 and December 2019 and admitted to our regional cardiac arrest center, 81 consecutive patients receiving Impella 2.5 during admission coronary angiogram were identified.

OUTCOMES/MEASUREMENTS

Survival outcomes were compared between those with Impella support pre-PCI to those with support post-PCI.

MAIN RESULTS

A total of 81 consecutive patients with infarct-related postcardiac arrest shock supported with Impella 2.5 during admission coronary angiogram were included. All patients were in profound cardiogenic shock requiring catecholamines at admission. Overall survival to discharge and at 6 months was 40.7% and 38.3%, respectively. Patients in the pre-PCI group had a higher survival to discharge and at 6 months as compared to patients of the post-PCI group (54.3% vs 30.4%; p = 0.04 and 51.4% vs 28.2%; p = 0.04, respectively). Furthermore, the patients in the early support group demonstrated a greater functional recovery of the left ventricle and a better restoration of the end-organ function when Impella support was initiated prior to percutaneous coronary intervention.

CONCLUSIONS

Our results suggest that the early initiation of mechanical circulatory support with Impella 2.5 prior to percutaneous coronary intervention is associated with improved hospital and 6-month survival in patients with postcardiac arrest cardiogenic shock complicating acute myocardial infarction.

Door-to-unload: left ventricular unloading before reperfusion in ST-elevation myocardial infarction

ST-elevation myocardial infarction treatment in the modern era has focused on minimizing time of ischemia by reducing door-to-balloon time to limit infarct size and improve survival. Although there have been significant improvements in minimizing time to coronary reperfusion, the incidence of heart failure following a myocardial infarction has remained high. Preclinical studies have shown that unloading the left ventricle for 30 min prior to coronary reperfusion can reduce infarct size and promote myocardial recovery. The DTU-STEMI randomized prospective trial will test the hypothesis that left ventricular unloading for at least 30 min prior to coronary reperfusion will improve infarct size and heart failure-related events as compared with the current standard of care.

Impella percutaneous left ventricular assist device as mechanical circulatory support for cardiogenic shock: A retrospective analysis from a tertiary academic medical center

OBJECTIVES

To describe hemodynamic efficacy and clinical outcomes of Impella percutaneous left ventricular assist device (pLVAD) in patients with cardiogenic shock (CS).

BACKGROUND

Percutaneous LVADs are increasingly used in CS management. However, device-related outcomes and optimal utilization remain active areas of investigation.

METHODS

All CS patients receiving pLVAD as mechanical circulatory support (MCS) between 2011 and 2017 were identified. Clinical characteristics and outcomes were analyzed. A multivariable logistic regression model was created to predict MCS escalation despite pLVAD. Outcomes were compared between early and late implantation.

RESULTS

A total of 115 CS patients (mean age 63.6 ± 13.8 years; 69.6% male) receiving pLVAD as MCS were identified, the majority with CS secondary to acute myocardial infarction (AMI; 67.0%). Patients experienced significant cardiac output improvement (median 3.39 L/min to 3.90 L/min, p = .002) and pharmacological support reduction (median vasoactive-inotropic score [VIS] 25.4 to 16.4, p = .049). Placement of extracorporeal membrane oxygenation (ECMO) occurred in 48 (41.7%) of patients. Higher pre-pLVAD VIS was associated with subsequent MCS escalation in the entire cohort and AMI subgroup (OR 1.27 [95% CI 1.02-1.58], p = .034 and OR 1.72 [95% CI 1.04-2.86], p = .035, respectively). Complications were predominantly access site related (bleeding [9.6%], vascular injury [5.2%], and limb ischemia [2.6%]). In-hospital mortality was 57.4%, numerically greater survival was noted with earlier device implantation.

CONCLUSIONS

Treatment with pLVAD for CS improved hemodynamic status but did not uniformly obviate MCS escalation. Mortality in CS remains high, though earlier device placement for appropriately selected patients may be beneficial.

Intraaortic Balloon Pump vs Peripheral Ventricular Assist Device Use in the United States

BACKGROUND

The objective of this study was to characterize practical use trends and outcomes for intraaortic balloon pump (IABP) and percutaneous left ventricular assist device (pVAD) use in cardiogenic shock at a national level.

METHODS

An analysis of all adult patients admitted nonelectively for cardiogenic shock from January 2008 through December 2017 was performed using the National Inpatient Sample. Trends of inpatient IABP and pVAD use were analyzed using survey-weighted estimates and the modified Cochran-Armitage test for significance. Multivariable regression models and inverse probability of treatment weights were used to perform risk-adjusted analyses of pVAD mortality, a composite of adverse events (AE), and resource use, with IABP as reference.

RESULTS

Of an estimated 774,310 patients admitted with cardiogenic shock, 143,051 received a device: IABP, 127,792 (16.5%); or pVAD, 15,259 (2.0%). IABP use decreased (23.8% to 12.7%; P for trend <.001), whereas pVAD implantation increased significantly during the study period (0.2% to 4.5%; P for trend <.001). Inverse probability of treatment weights demonstrated significantly higher odds of mortality with pVAD (odds ratio, 1.9; 95% confidence interval, 1.7 to 2.2), but not AE (odds ratio, 1.1; 95% confidence interval, 0.96 to 1.27), compared with IABP. After risk adjustment, pVAD use was associated with an additional $15,202 (P < .001) in cost for survivors and $29,643 for nonsurvivors (P < .001).

CONCLUSIONS

Over the study period, the rate of pVAD use for cardiogenic shock significantly increased. Compared with IABP, pVAD use was associated with increased mortality, higher costs, and several AEs. Multi-institutional clinical trials with rigorous inclusion criteria are warranted to evaluate the clinical utility of pVADs in the modern era.

Impaired left ventricular global longitudinal strain is associated with elevated left ventricular filling pressure after myocardial infarction

Left ventricular (LV) global longitudinal strain (GLS) has emerged as a significant prognostic marker in patients after myocardial infarction (MI). Although elevated LV filling pressure after MI might alter GLS, direct evidence for this is lacking. This study aimed to clarify the association between GLS and LV filling pressure in a large animal MI model. A total of 104 Yorkshire pigs underwent both echocardiographic and hemodynamic assessments 1-4 wk after induction of large anterior MI. GLS was measured in the apical four-chamber view using a semiautomated speckle-tracking software. LV pressure-volume relationship was invasively measured using a high-fidelity pressure-volume catheter. GLS >-14% was considered impaired. Compared with pigs with LV ejection fraction (LVEF) >40% and preserved GLS (n = 29), those with LVEF >40% and impaired GLS (n = 37) and those with LVEF ≤40% (n = 38) had significantly higher LV end-diastolic pressure (15.5 ± 5.5 vs. 19.7 ± 5.8 and 19.6 ± 6.6 mmHg; P = 0.008 and P = 0.026, respectively) and higher LV mean diastolic pressure (7.1 ± 2.9 vs. 10.4 ± 4.5 and 11.1 ± 5.4 mmHg; P = 0.013 and P = 0.002, respectively). GLS was modestly correlated with τ (r = 0.21, P = 0.039) and slope of LV end-diastolic pressure-volume relationship (r = 0.43, P < 0.001). Impaired GLS was associated with higher LV end-diastolic and mean-diastolic pressures after adjusting for LVEF and baseline characteristics (P = 0.026 and P = 0.001, respectively). Impaired GLS assessed by speckle-tracking echocardiography was associated with elevated LV filling pressure after MI. GLS has an incremental diagnostic value for detecting elevated LV filling pressure and may be particularly useful for evaluating post-MI patients with preserved LVEF.NEW & NOTEWORTHY Strain analysis was performed in 104 pigs after MI, and its relationship to invasive hemodynamic measurements was studied. Impaired longitudinal strain was associated with high ventricular filling pressure independent of LVEF in post-MI setting. Global longitudinal strain is a potential prognostic marker after MI.

Novel Porcine Model of Coronary Dissection Reveals the Impact of Impella on Dissected Coronary Arterial Hemodynamics

Background: Coronary artery dissection (CAD) sometimes accompanies unstable hemodynamics and requires mechanical cardiac support. Meanwhile, mechanical cardiac support may influence coronary hemodynamics in CAD. No study has examined the impact of Impella left ventricular (LV) support on CAD. Materials and Methods: CAD was induced in eight Yorkshire pigs by injuring the left anterior descending artery (LAD) using a 0.018-in. stiff guidewire and/or deep engagement of a blunt-cut coronary guiding catheter. After the creation of CAD, hemodynamic parameters, coronary pressure, and flow as well as coronary angiograms were acquired before and after maximum LV support using the Impella CP. Result: CADs with a large flap were successfully created by deep engagement of a blunt-tip guiding catheter with forceful contrast injection. One animal (#8) exhibited thrombolysis in myocardial infarction (TIMI)-1 flow, while the others (animals #1-#7) showed TIMI-2/3 flow. In TIMI-2/3 animals, maximal Impella support increased mean coronary pressure (108.4 ± 22.5 to 124.7 ± 28.0 mmHg, P < 0.001) with unchanged mean coronary flow velocity (63.50 ± 28.66 to 48.32 ± 13.30 cm/s, P = 0.17) of the LAD distal to the dissection. The LV end-diastolic pressure (20.6 ± 6.6 vs. 12.0 ± 3.4 mmHg, P = 0.032), LV end-diastolic volume (127 ± 32 vs. 97 ± 26 ml, P = 0.015), stroke volume (68 ± 16 vs. 48 ± 14 ml, P = 0.003), stroke work (5,744 ± 1,866 vs. 4,424 ± 1,650 mmHg·ml, P = 0.003), and heart rate (71.4 ± 6.6 vs. 64.9 ± 9.3/min, P = 0.014) were all significantly reduced by Impella support, indicating effective unloading of the LV. In the TIMI-1 animal (animal #8), maximal Impella support resulted in further delay in angiographic coronary flow and reduced distal coronary pressure (22.9-17.1 mmHg), together with increased false-lumen pressure. Conclusion: Impella support effectively unloaded the LV and maintained the hemodynamics in a novel porcine model of CAD. Coronary pressure distal to the dissection was increased in TIMI-2/3 animals after Impella support but decreased in the animal with initial TIMI-1 flow.

Large Animal Models of Heart Failure: A Translational Bridge to Clinical Success

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Preclinical large animal models play a critical and expanding role in translating basic science findings to the development and clinical approval of novel cardiovascular therapeutics.

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This state-of-the-art review outlines existing methodologies and physiological phenotypes of several HF models developed in large animals. A comprehensive list of porcine, ovine, and canine models of disease are presented, and the translational importance of these studies to clinical success is highlighted through a brief overview of recent devices approved by the FDA alongside associated clinical trials and preclinical animal reports.

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Increasing the use of large animal models of HF holds significant potential for identifying new mechanisms underlying this disease and providing valuable information regarding the safety and efficacy of new therapies, thus, improving physiological and economical translation of animal research to the successful treatment of human HF.

Preclinical large animal models of heart failure (HF) play a critical and expanding role in translating basic science findings to the development and clinical approval of novel therapeutics and devices. The complex combination of cardiovascular events and risk factors leading to HF has proved challenging for the development of new treatments for these patients. This state-of-the-art review presents historical and recent studies in porcine, ovine, and canine models of HF and outlines existing methodologies and physiological phenotypes. The translational importance of large animal studies to clinical success is also highlighted with an overview of recent devices approved by the Food and Drug Administration, together with preclinical HF animal studies used to aid both development and safety and/or efficacy testing. Increasing the use of large animal models of HF holds significant potential for identifying the novel mechanisms underlying the clinical condition and to improving physiological and economical translation of animal research to successfully treat human HF.

Comparison of Hemodynamic Support by Impella vs. Peripheral Extra-Corporeal Membrane Oxygenation: A Porcine Model of Acute Myocardial Infarction

Objectives: Several mechanical circulatory assist devices are used to treat critically ill patients requiring hemodynamic support during post-myocardial infarction or cardiogenic shock. However, little guidance is available to choose an appropriate device to match a particular patient's needs. An increased understanding of hemodynamic effects of the pump systems and their impact on myocardial pre-/afterload might help to better understand their behavior in different clinical settings. Methods: This was an open-labeled, randomized acute animal experiment. A model of acute univentricular myocardial injury by temporary balloon occlusion was used. The experiment was carried out in 10 juveniles female Piétrain pigs. The animals were randomized to mechanical hemodynamic support either by peripheral veno-arterial (VA-)ECMO or Impella CP. Results: While both devices were able to provide flows above 3 L/min and maintain sufficient end-organ perfusion, support by Impella resulted in a significantly more pronounced immediate effect on myocardial unloading: At the onset of device support, the remaining native cardiac output was reduced by 23.5 ± 15.3% ECMO vs. 66.2 ± 36.2% (Impella, p = 0.021). Native stroke volume was significantly decreased by Impella support compared to ECMO, indicating less mechanical work being conducted by the Impella-supported hearts despite similar total assisted cardiac output. Conclusions: Peripheral VA-ECMO and the transaortic Impella pump resulted in contrasting hemodynamic fingerprints. Both devices provided sufficient hemodynamic support and reduce left ventricular end-diastolic pressure in the acute setting. Treatment with the Impella device resulted in a more effective volume unloading of the left ventricle. A significant reduction in myocardial oxygen consumption equivalent was achieved by both devices: The Impella device resulted in a left-shift of the pressure-volume loop and a decreased pressure-volume-area (PVA), while VA-ECMO increased PVA but decreased heart rate. These data highlight the importance of specifically targeting heart rate in the management of AMI patients on hemodynamic support.

Collaborative Cardiac Care: A Comprehensive Heart Team Approach to Multiple Severe Vascular Conditions

Left main artery coronary disease represents the highest risk lesion of ischemic heart disease. Revascularization can be accomplished by surgery or percutaneous interventions. This study highlights the case of a patient with severe multiple peripheral vascular conditions and complex coronary anatomy treated with percutaneous coronary intervention using mechanical circulatory support. (Level of Difficulty: Intermediate.)

Echocardiographic Left Ventricular Mass Estimation: Two-Dimensional Area-Length Method is Superior to M-Mode Linear Method in Swine Models of Cardiac Diseases

Echocardiography offers rapid and cost-effective estimations of left ventricular (LV) mass, but its accuracy in patients with cardiac disease remains unclear. LV mass was measured by M-mode-based linear method and two-dimensional echocardiography (2DE)-based area-length method in pig models and correlation with actual LV weight was assessed. Twenty-six normal, 195 ischemic heart disease (IHD), and 33 non-IHD HF pigs were included. A strong positive linear relationship to the actual LV weight was found with 2DE-based area-length method (r = 0.82, p < 0.001), whereas a moderate relationship was found with M-mode method in the overall population (r = 0.68, p < 0.001). Two correlation coefficients were significantly different (p < 0.001), and were driven mainly by incremental overestimation of LV mass in heavier hearts using the M-mode method. IHD and LV dilation were the factors contributing to overestimation using M-mode method. 2DE-based area-length method provides a better estimation of LV weight in swine models of HF, particularly in those with IHD.

Acute Left Ventricular Unloading Reduces Atrial Stretch and Inhibits Atrial Arrhythmias

BACKGROUND

Left atrium (LA) physiology is influenced by changes in left ventricular (LV) performance and load.

OBJECTIVES

The purpose of this study was to define the effect of acute changes in LV loading conditions on LA physiology in subacute myocardial infarction (MI).

METHODS

MI was percutaneously induced in 19 Yorkshire pigs. One to 2 weeks after MI, 14 pigs underwent acute LV unloading using a percutaneous LV assist device, Impella. The remaining 5 pigs underwent acute LV loading by percutaneous induction of aortic regurgitation. A pressure-volume catheter was inserted into the LA using a percutaneous transseptal approach, and LA pressure-volume loops were continuously monitored. Atrial arrhythmia inducibility was examined by burst-pacing of the right atrium. Nicotinamide adenine dinucleotide phosphate oxidase (NOX) levels and ryanodine receptor phosphorylation were examined in LA tissues to study the potential effect of stretch-dependent oxidative stress.

RESULTS

MI resulted in reduced LV ejection fraction and increased LV end-diastolic pressure with concomitant increase in LA pressure and volumes. Acute LV unloading resulted in a reduction of LV end-diastolic pressure, which led to proportional decreases in mean LA pressure and maximum LA volume. LA pressure-volume loops exhibited a pump flow-dependent, left-downward shift. This was associated with reduced LA passive stiffness, suggesting the alleviation of the LA stretch that was present after MI. Prior to acute unloading of the LV, 71% of the pigs were arrhythmia-inducible; LV unloading reduced this to 29% (p = 0.02). Time to spontaneous termination of atrial arrhythmias was decreased from median 55 s (range 5 to 300 s) to 3 s (range 0 to 59 s). In contrast, acute LV loading with aortic regurgitation increased LA pressure without a significant effect on arrhythmogenicity. Molecular analysis of LA tissue revealed that NOX2 expression was increased after MI, whereas acute LV unloading reduced NOX2 levels and diminished ryanodine receptor phosphorylation.

CONCLUSIONS

Acute LV unloading relieves LA stretch and reduces atrial arrhythmogenicity in subacute MI.

Clinical scenarios for use of transvalvular microaxial pumps in acute heart failure and cardiogenic shock - A European experienced users working group opinion

For patients with myocardial infarct-related cardiogenic shock (CS), urgent percutaneous coronary intervention is the recommended treatment strategy to limit cardiac and systemic ischemia. However, a specific therapeutic intervention is often missing in non-ischemic CS cases. Though drug treatment with inotropes and/or vasopressors may be required to stabilize the patient initially, their ongoing use is associated with excess mortality. Coronary intervention in unstable patients often leads to further hemodynamic compromise either during or shortly after revascularization. Support devices like the intra-aortic balloon pump failed to improve clinical outcomes in infarct-related CS. Currently, more powerful and active hemodynamic support devices unloading the left ventricle such as transvalvular microaxial pumps are available and are being increasingly used. However, as for other devices large randomized trials are not yet available, and device use is based on registry data and expert consensus. In this article, a multidisciplinary group of experienced users of transvalvular microaxial pumps outlines the pathophysiological background on hemodynamic changes in CS, the available mechanical support devices, and current guideline recommendations. Furthermore, different hemodynamic situations in several case-based scenarios are used to illustrate candidate settings and to provide the theoretic and scientific rationale for left-ventricular unloading in these scenarios. Finally, organization of shock networks, monitoring, weaning, and typical complications and their prevention are discussed.