Comparative analysis of survival rate and quality of life in axial-flow pump left ventricular assist devices (LVADs)

BACKGROUND

The rising heart failure rates globally show the pressing demand for treatment progress, especially in Left Ventricular Assist Devices (LVADs). Axial-flow pump LVADs are gaining notice for their small size, few moving parts, and potential for miniaturization, providing a vital option for heart transplants during donor shortages.

OBJECTIVES

Despite several studies on LVADs, there is a notable lack of research specifically comparing axial-flow pumps with similar technology. This gap hinders the identification of the most optimal technology to guide development efforts and meet patient needs. This study aims to comprehensively compare the most commonly used axial-flow pumps and provide a detailed analysis focusing on survival rates and quality of life parameters.

METHODS

As a developer of axial-flow pumps (LVADs), our group conducted a systematic review of the current axial-flow pump LVADs. We analyzed studies comparing these devices, focusing on key metrics such as survival rates and quality of life.

RESULTS

The HeartMate 2 and Jarvik 2000 show superior survival rates (up to 86.9 % at 6 months, 96.3 % at 3 years) and (6-month survival 67 %-91 %) respectively, compared to the other axial flow pumps LVAD. The results underscore the importance of choosing the optimal device and informing the direction of future developments.

CONCLUSION

In this paper, we aim to inform future studies to enhance their effectiveness and advance the overall performance of these devices, ultimately benefiting patients and developers. This review furnishes evidence-based recommendations for the most appropriate axial-flow pumps based on survival rates and quality of life parameters.

Effect of RVAD Cannulation Length on Right Ventricular Thrombosis Risk: An In Silico Investigation

Left ventricular assist devices (LVADs) have been used off-label as long-term support of the right heart due to the lack of a clinically approved durable right VAD (RVAD). Whilst various techniques to reduce RVAD inflow cannula protrusion have been described, the implication of the protrusion length on right heart blood flow and subsequent risk of thrombosis remains poorly understood. This study investigates the influence of RVAD diaphragmatic cannulation length on right ventricular thrombosis risk using a patient-specific right ventricle in silico model validated with particle image velocimetry. Four cannulation lengths (5, 10, 15 and 25 mm) were evaluated in a one-way fluid-structure interaction simulation with boundary conditions generated from a lumped parameter model, simulating a biventricular supported condition. Simulation results demonstrated that the 25-mm cannulation length exhibited a lower thrombosis risk compared to 5-, 10- and 15-mm cannulation lengths due to improved flow energy distribution (25.2%, 24.4% and 17.8% increased), reduced stagnation volume (72%, 68% and 49% reduction), better washout rate (13.0%, 11.6% and 9.1% faster) and lower blood residence time (6% reduction). In the simulated scenario, our findings suggest that a longer RVAD diaphragmatic cannulation length may be beneficial in lowering thrombosis risk; however, further clinical studies are warranted.

HeartMate-3 Ventricular Assist Devices Versus the Total Artificial Heart for Biventricular Support: A Single-Center Series

INTRODUCTION

The SynCardia total artificial heart (TAH) is the only device approved for biventricular support. Continuous flow ventricular assist devices (VAD) in a biventricular configuration (BiVAD) have been used with variable results. The purpose of this report was to examine differences in patient characteristics and outcomes between two HeartMate-3 (HM-3) VADs in comparison with TAH support.

METHODS

All patients who received durable biventricular mechanical support from November 2018 to May 2022 at The Mount Sinai Hospital (New York) were considered. Baseline clinical, echocardiographic, hemodynamic, and outcome data were extracted. Primary outcomes were postoperative survival and successful bridge-to-transplant (BTT).

RESULTS

A total of 16 patients received durable biventricular mechanical support during the study period, of which 6 (38%) patients received two HM-3 VAD pumps as BiVAD support and 10 (62%) patients received a TAH. Overall, TAH patients had a lower median lactate ( p < 0.05) at baseline compared to those on HM-3 BiVAD support yet had higher operative morbidity, lower 6-month survival ( p < 0.05), and a higher rate of renal failure (80 vs . 17%; p = 0.03). However, survival declined to the same rate at 1 year (50%) and was largely because of extracardiac adverse events related to underlying comorbidities (particularly, renal failure and diabetes, p < 0.05). Successful BTT was achieved in 3 out of 6 HM-3 BiVAD patients and in 5 out of 10 TAH patients.

CONCLUSION

In our single center experience, similar outcomes were observed among patients BTT with HM-3 BiVAD compared to those BTT on TAH support despite lower Interagency Registry for Mechanically Assisted Circulatory Support level.

Long-term assist device patients admitted to ICU: Tips and pitfalls

Left ventricular assist device (LVAD) therapy is well-established in the treatment of end-stage cardiac failure. Indications are bridge to transplant (BTT), bridge to candidacy (BTC), bridge to recovery (BTR), and destination therapy (DT). The durability and adverse event (AE) rate of LVADs have improved over the years. However, due to donor shortage, the duration of support in the BTT population has increased tremendously; similarly, DT patients are on the device for a long time. Consequently, the number of readmissions of long-term LVAD patients has increased. In cases of severe AEs, intensive care unit (ICU) treatment can be necessary. Infectious complications are the most common AE. Furthermore, embolic or hemorrhagic strokes can occur due to foreign surfaces, acquired von Willebrand syndrome, and anticoagulation treatment. Another consequence of the coagulative status, in combination with the continuous flow, are gastrointestinal bleeding events. Moreover, in most patients, an isolated LVAD is implanted, and this involves the risk of late right heart failure. Adjustment of pump speed and optimization of the volume status can help solve this issue. Malignant arrhythmias, pre-existing or de novo after LVAD implantation, can be a life-threatening AE. Antiarrhythmic medical therapy or ablation are potential treatment options. As for specific LVADs, the Medtronic HeartWare™ ventricular assist device (HVAD) is not manufactured and distributed currently; however, 4000 patients are still on the device. Pump thrombosis can occur, wherein thrombolytic therapy is the first-line treatment option. Additionally, the HVAD can fail to restart after controller exchange due to technical issues, and precautions must be taken. The Momentum 3 trial showed superior survival without pump exchange or disabling stroke in patients treated with the HeartMate 3^Ⓡ (HM3; Abbott, Abbott Park, IL, USA) device in comparison to the HeartMate II (HMII). However, in a few cases, a twisted graft or bio debris formation between the outflow graft and bend relief could be observed, causing outflow graft obstruction. Patients on LVADs are still heart failure patients, in many cases with comorbidities. Therefore, many situations can occur requiring ICU treatment. Ethical aspects should always be the focus when taking care of these patients.

Evaluation of Centrifugal Blood Pump Performances for Biventricular Support in Virtual Simulation Model

BACKGROUND

Despite the advances in the left ventricular assist device (LVAD), there are still situations that require a biventricular assist device (BVAD) system. The purpose of this study was to explore and compare the system performance interactions with the HeartMate3 (HM3) and HeartWare (HVAD) in a BVAD configuration using the virtual mock loop (VML) simulation tool.

METHODS

The VML simulation tool is an in silico implementation of a lumped parameter model of the cardiovascular system with mechanical circulatory support. Patients with ejection fractions of 60%, 20%, and 15% were simulated in VML, and the HVAD and HM3 in a BVAD with ventricular cannulation were applied to simulated conditions. Pump speeds that restored baseline normal hemodynamics were determined. To determine the optimal speeds for BVAD, the left and right arterial pressures (LAP, RAP) were plotted.

RESULTS

In the HVAD, LAP and RAP balanced at 11 mm Hg with LVAD 3,500 rpm, right ventricular assist device (RVAD) 2,200 rpm; at 13 mm Hg with LVAD 3,000 rpm, RVAD 1,700 rpm; and at 14 mm Hg with LVAD 2,500 rpm, RVAD 1,300 rpm. For the HM3, at 8 mm Hg with LVAD 7,000 rpm, RVAD 5,000 rpm; at 9 mm Hg with LVAD 6,000 rpm, RVAD 4,300 rpm; and at 9.5 mm Hg with LVAD 5,000 rpm, RVAD 3,500 rpm.

CONCLUSION

The RVAD/LVAD speed ratios required for atrial balance were approximately 0.6 for the HVAD and 0.7 for the HM3. However, the HVAD required RVAD speeds below its range of operation.

Contemporary outcomes of continuous-flow biventricular assist devices

Background

Significant right ventricular failure (RVF) complicating left ventricular assist device (LVAD) placement has been reported at 10-30%. Although primarily indicated for left ventricular failure, ventricular assist devices (VADs) have become utilized in a biventricular setup to combat right ventricular failure (RVF) following LVAD implantation. With the advent of continuous-flow LVADs (CF-LVADs) superseding their pulsatile predecessors, the shift towards CF-biventricular assist devices (CF-BiVADs) come with the prospect of improved outcomes over previous pulsatile BiVADs. We aim to review the literature and determine the outcomes of CF-BiVAD recipients.

Methods

A systematic review was performed to determine the outcomes of CF-BiVADs. Pre-operative demographics and device configuration data was collected. Primary outcomes evaluated were short-term survival, long-term survival, duration of support, and survival to transplant. Secondary outcomes evaluated included intensive care unit (ICU) and hospital length of stay (ICU-LOS and HLOS, respectively), pump thrombosis, pump exchange. Median and interquartile range was reported where appropriate. A major limitation was the likely overlap of cohorts across publications, which may have contributed to some selection bias.

Results

Of 1,282 screened, 12 publications were evaluated. Sample size ranged from 4 to 93 CF-BiVAD recipients, and follow-up ranged from 6 to 24 months. Mean age ranged from 34 to 52 years old. Forty-five percent of CF-BiVADs had right atrial (RA-) inflow cannulation, with the remaining being right ventricular (RV). Thirty-day survival was a median of 90% (IQR 82-97.8%) and 12-month survival was a median of 58.5% (IQR 47.5-62%). Where reported, rate of pump thrombosis (predominantly the right VAD) was a median of 31% (IQR 14-36%), although pump exchange was only 9% (IQR 1.5-12.5%).

Conclusions

RVF post-LVAD implantation is a high morbidity and mortality complication. There is no on-label continuous-flow RVAD currently available. Thus, the modifications of LVADs for right ventricular support to combat pump thrombosis has resulted in various techniques. BiVAD recipients are predominantly transplant candidates, and complications of pump thrombosis and driveline infection whilst on wait-list are of great consequence. This study demonstrates the need for an on-label CF-BiVAD.

Conventional and alternative sites for left ventricular assist device inflow and outflow cannula placement

Left ventricular assist device (LVAD) therapy is a well accepted and effective strategy to treat advanced heart failure. The miniaturized third-generation centrifugal pumps HeartWare HVAD (Medtronic, Dublin, Ireland) and HeartMate 3 (Abbott, Illinois, USA) are the two most commonly implanted systems in the contemporary era. Their design has allowed clinicians to pioneer several alternate and less invasive implantation techniques to tackle a broad spectrum of clinical scenarios. A brief review and discussion of alternative surgical techniques for both inflow and outflow cannula insertion, in the contemporary LVAD surgery era, are herein reported.

Durable Continuous-Flow Mechanical Circulatory Support: State of the Art

Implantable mechanical circulatory support (MCS) systems for ventricular assist device (VAD) therapy have emerged as an important strategy due to a shortage of donor organs for heart transplantation. A growing number of patients are receiving permanent assist devices, while fewer are undergoing heart transplantation (Htx). Continuous-flow (CF) pumps, as devices that can be permanently implanted, show promise for the treatment of both young and old patients with heart failure (HF). Further improvement of these devices will decrease adverse events, enable pulse modulation of continuous blood flow, and improve automatic remote monitoring. Ease of use for patients could also be improved. We herein report on the current state of the art regarding implantable CF pumps for use as MCS systems in the treatment of advanced refractory HF.

Long-term biventricular support following myocardial infarction from anterior descending coronary artery damage due to stabbing: A case report

BACKGROUND

The use of dual continuous-flow assist devices for biventricular support remains novel with only small case series or reports documenting outcomes.

METHODS

We describe a 21-year-old woman suffered stabbing with damage of coronary artery with subsequent myocardial infarction and severe postinfarction heart failure with impaired right ventricular function. The patient underwent implantation of two continuous-flow ventricular assist devices.

RESULTS

The early postoperative period was followed by severe respiratory insufficiency and an asthenic syndrome, which required prolonged intensive care and mechanical ventilation. After prolonged hospital stay, she was discharged home waiting for heart transplantation.

CONCLUSIONS

With the continuing miniaturization of pump designs, less invasive, more durable and cost-effective pumps have become available for dual assist device therapy in in these critically ill heart failure patients.

2019 EACTS Expert Consensus on long-term mechanical circulatory support

Long-term mechanical circulatory support (LT-MCS) is an important treatment modality for patients with severe heart failure. Different devices are available, and many-sometimes contradictory-observations regarding patient selection, surgical techniques, perioperative management and follow-up have been published. With the growing expertise in this field, the European Association for Cardio-Thoracic Surgery (EACTS) recognized a need for a structured multidisciplinary consensus about the approach to patients with LT-MCS. However, the evidence published so far is insufficient to allow for generation of meaningful guidelines complying with EACTS requirements. Instead, the EACTS presents an expert opinion in the LT-MCS field. This expert opinion addresses patient evaluation and preoperative optimization as well as management of cardiac and non-cardiac comorbidities. Further, extensive operative implantation techniques are summarized and evaluated by leading experts, depending on both patient characteristics and device selection. The faculty recognized that postoperative management is multidisciplinary and includes aspects of intensive care unit stay, rehabilitation, ambulatory care, myocardial recovery and end-of-life care and mirrored this fact in this paper. Additionally, the opinions of experts on diagnosis and management of adverse events including bleeding, cerebrovascular accidents and device malfunction are presented. In this expert consensus, the evidence for the complete management from patient selection to end-of-life care is carefully reviewed with the aim of guiding clinicians in optimizing management of patients considered for or supported by an LT-MCS device.

Mechanical circulatory support for the right ventricle in combination with a left ventricular assist device

Introduction: Right heart failure (RHF) in patients with a left ventricular assist device (LVAD) carries a poor prognosis although the treatment strategy including mechanical circulatory support for the failing right ventricle (RV) has not been well established. Areas covered: In this review, we describe an overview of RHF post-LVAD implant including natural history, prevalence, pathophysiology, outcomes, and challenges to predict RHF post-LVAD implant. Then, we focus on right ventricular assist devices (RVADs) and their clinical outcomes. Recently developed percutaneous RVADs are the major advance in this field. Finally, we discuss future perspectives to overcome limitations of the current treatment options. Expert opinion: In the absence of dedicated RVAD system RHF post-LVAD implant may have been undertreated. Now that dedicated percutaneous RVADs have emerged, surgeons are encouraged to use these new devices to improve outcomes of LVAD therapy. As experience accumulates, we should be able to establish the best possible strategy to treat early RHF post-LVAD implant. Late RHF is another form of RHF post-LVAD implant and has been underappreciated. Further research is mandatory to clarify the mechanism and risk factors. There are still unmet needs for a dedicated implantable RVAD for a subset of patients who need long-term RV support.

Temporary mechanical circulatory support for refractory heart failure: the German Heart Center Berlin experience

Background

Temporary mechanical circulatory support (MCS) offers a valuable option for treatment of refractory heart failure. We present our experience with selected MCS devices in cardiogenic shock of different etiologies.

Methods

We retrospectively studied patients who were treated in our institution between 01/2016 and 07/2018. Patients receiving only veno-arterial extracorporeal membrane oxygenation (VA-ECMO) support were excluded. Left ventricular support patients received Impella; right ventricular support was conducted using Levitronix CentriMag.

Results

Thirty-seven patients received an Impella left ventricular assist device (LVAD). Etiology was: acute on chronic ischemic cardiomyopathy (ICMP; n=12), acute myocardial infarction (AMI; n=11), dilated cardiomyopathy (DCMP; n=7) and toxic cardiomyopathy (TCMP; n=2). Two patients presented with postcardiotomy shock and acute myocarditis, respectively. In one case, Takotsubo cardiomyopathy was diagnosed. Impella was used solely in 28 patients (Impella group) with an in-hospital survival of 37%. In nine patients, Impella was used in combination with extracorporeal life support (ECLS) implantation (ECMELLA group)-in-hospital survival was 33%. In the Impella group six patients recovered, six received a long-term VAD and 16 died on device. In the ECMELLA group one patient recovered, three received a long-term VAD and five died. The majority of CentriMag implantations as a right ventricular assist device (RVAD) were necessary after LVAD implantation (n=52); of these patients, 14 recovered, eight received long-term VAD and 30 died. The remaining 17 patients were supported by RVAD due to AMI (n=7); postcardiotomy (n=7); right heart failure after heart transplantation (n=2) and ICMP (n=1). Six of these patients recovered, two required long-term VAD and nine died.

Conclusions

Survival after MCS implantation for left as well as right heart failure in cardiogenic shock remains low, but is superior to that of patients without mechanical support. Short-term MCS remains an option of choice if right, left or biventricular support is needed.