Ventricular Recovery and Pump Explantation in Patients Supported by Left Ventricular Assist Devices: A Systematic Review

Deactivation of LVAD support for myocardial recovery-surgical perspectives

Left ventricular assist devices (LVADs) are excellent therapies for advanced heart failure patients either bridged to transplant or for lifetime use. LVADs also allow for reverse remodeling of the failing heart that is often associated with functional improvement. Indeed, growing enthusiasm exists to better understand this population of patients, whereby the LVAD is used as an adjunct to mediate myocardial recovery. When patients achieve benchmarks suggesting that they no longer need LVAD support, questions related to the discontinuation of LVAD therapy become front and center. The purpose of this review is to provide a surgical perspective on the practical and technical issues surrounding LVAD deactivation.

Percutaneous Decommissioning 11 Years After Initial CF-LVAD Placement

An 80-year-old man with severe nonischemic cardiomyopathy status post left ventricular assist device (LVAD) placement 11 years prior presented for recurrent LVAD alarms from internal driveline fracture. Given his partial myocardial recovery and his preference to avoid surgical procedures, percutaneous LVAD decommissioning was performed by occlusion of the outflow graft and subsequently driveline removal. (Level of Difficulty: Advanced.)

Initial clinical validation of a hybrid in silico—in vitro cardiorespiratory simulator for comprehensive testing of mechanical circulatory support systems

Simulators are expected to assume a prominent role in the process of design—development and testing of cardiovascular medical devices. For this purpose, simulators should capture the complexity of human cardiorespiratory physiology in a realistic way. High fidelity simulations of pathophysiology do not only allow to test the medical device itself, but also to advance practically relevant monitoring and control features while the device acts under realistic conditions. We propose a physiologically controlled cardiorespiratory simulator developed in a mixed in silico-in vitro simulation environment. As inherent to this approach, most of the physiological model complexity is implemented in silico while the in vitro system acts as an interface to connect a medical device. As case scenarios, severe heart failure was modeled, at rest and at exercise and as medical device a left ventricular assist device (LVAD) was connected to the simulator. As initial validation, the simulator output was compared against clinical data from chronic heart failure patients supported by an LVAD, that underwent different levels of exercise tests with concomitant increase in LVAD speed. Simulations were conducted reproducing the same protocol as applied in patients, in terms of exercise intensity and related LVAD speed titration. Results show that the simulator allows to capture the principal parameters of the main adaptative cardiovascular and respiratory processes within the human body occurring from rest to exercise. The simulated functional interaction with the LVAD is comparable to the one clinically observed concerning ventricular unloading, cardiac output, and pump flow. Overall, the proposed simulation system offers a high fidelity in silico-in vitro representation of the human cardiorespiratory pathophysiology. It can be used as a test bench to comprehensively analyze the performance of physically connected medical devices simulating clinically realistic, critical scenarios, thus aiding in the future the development of physiologically responding, patient-adjustable medical devices. Further validation studies will be conducted to assess the performance of the simulator in other pathophysiological conditions.

Left Ventricular Assist Device as a Bridge to Recovery: Single Center Experience of Successful Device Explantation

Continuous-flow left ventricular assist devices (CF-LVAD) have been shown to enhance reverse remodeling and myocardial recovery in certain patients allowing for device removal. We sought to analyze the characteristics and describe outcomes of patients who underwent CF-LVAD explantation at a large academic center. We retrospectively identified all patients who underwent CF-LVAD explants due to recovery from 2006 to 2019. Patient baseline characteristics and data on pre- and postexplant evaluation were collected and analyzed. Of 421 patients who underwent CF-LVAD implantation, 13 underwent explantation (3.1%). Twelve HeartMate II and one HeartWare LVAD were explanted. All patients had nonischemic cardiomyopathy. Median time from heart failure diagnosis to LVAD implant was 12 months (interquartile range [IQR], 2-44) and the median time supported on LVAD was 22 months (IQR, 11-28). Two patients died within 30 days of explant. Three additional patients died during the follow-up period and all were noted to be nonadherent to medical therapy. After a mean follow-up duration of 5 years, overall survival was 52%. Mean pre-explant ejection fraction was 49%, which decreased at most recent follow-up to 32%. Mean pre-explant left ventricular internal diameter in diastole (LVIDD) was 4.37 cm and increased to 5.52 cm at most recent follow-up. Continuous-flow left ventricular assist device explantation is feasible and safe in select patients.

Percutaneous approach to left ventricular assist device decommissioning

OBJECTIVE

To assess the outcomes of a single-center experience with percutaneous left ventricular assist device (LVAD) decommissioning.

BACKGROUND

Patients with LVADs may eventually require their removal, either due to recovery of left ventricular function or recurrent complications. Traditionally, withdrawal of LVAD support has been managed with surgical device explantation, which carries significant procedural risks. Transcatheter LVAD decommissioning, with outflow graft occlusion and driveline transection, has recently been described as an alternative to surgical removal.

METHODS

Here, we report on a retrospective cohort of five consecutive cases treated with transcatheter LVAD decommissioning.

RESULTS

The procedure was effective in all cases, and no patient experienced procedure-related complications. At midterm follow-up, the three patients who had myocardial function recovery were alive and had not experienced heart failure-related symptoms or complications.

CONCLUSION

Percutaneous LVAD decommissioning appears to be a safe and effective approach to LVAD treatment discontinuation.

Left Ventricular Hemodynamics and Relationship with Myocardial Recovery and Optimization in Patients Supported on CF-LVAD Therapy

BACKGROUND

Despite interest in left ventricular (LV) recovery, there is an absence of data on the relationship between intrinsic LV hemodynamics and both reverse remodeling on continuous flow left ventricular assist device (CF-LVAD) therapy. We hypothesized that markers of intrinsic LV function would be associated with remodeling, optimization, and outcomes.

METHODS

Patients with continuous flow LVADs between 2015 and 2019 who underwent combined left and right heart catheterization (LHC/RHC) ramp protocol at a single institution were enrolled. Patients were stratified by response to CF-LVAD therapy: full responders (FR), partial responders (PR), or non-responders (NR) per Utah-Inova criteria. Hemodynamic data, including LV hemodynamics of peak LV dP/dt and tau (τ) were obtained at each phase. One-year heart failure hospitalization-free survival was the primary endpoint.

RESULTS

Among 61 patients included in the current study 38 (62%) were classified as NR, 14 (23%) PR, and 9 (15%) FR. Baseline LV dP/dt and τ varied by response status (P≤.02) and generally correlated with reverse remodeling on linear regression. Biventricular filling pressures varied with τ and there was an interaction effect of speed on the relationship between τ and PCWP (P=.04). Lastly, τ was a prognostic marker and associated with one-year HF-hospital free survival (OR 1.04, 95%CI 1.00-1.07, P=.02 per ms increase).

CONCLUSIONS

Significant correlations between τ and LV dP/dt and reverse remodeling were noted with tau serving as a prognostic marker. Higher LVAD speed was associated with a greater reliance on LVAD for unloading. Future work should focus on defining the optimal level of LVAD support in relation to LV recovery.

Left Ventricular Assist Device Reinsertion for Recurrence of End-Stage Heart Failure Eleven Years after Device Removal: Case Report

After demonstrated myocardial recovery in patients with durable left ventricular assist device (LVAD) support, the device may occasionally be explanted. A 38-year-old female with nonischemic cardiomyopathy underwent implantation of an LVAD as a bridge-to-transplant therapy. After one year, the patient demonstrated sufficient myocardial recovery allowing the LVAD to be explanted. A Teflon felt strip plug was created and placed within the apical sewing ring to occlude the opening into the left ventricle. Eleven years later, the patient presented with recurrence of severe heart failure. Due to morbid obesity, the patient was not a heart transplant candidate. Therefore, a second LVAD was implanted with a concomitant gastric sleeve procedure. When the plug was surgically removed from the sewing ring, no thrombus was observed; however, the ventricular surface was completely endothelialized. The patient recovered without any complications, was discharged from the hospital, and is currently listed for a heart transplant. This case demonstrates remission from heart failure lasting for more than a decade. If a second LVAD is needed due to exacerbation of severe heart failure, it can be safely introduced through the previous sewing ring after removing the Teflon plug.

The ethics of explantation

BACKGROUND

With the increased use of implanted medical devices follows a large number of explantations. Implants are removed for a wide range of reasons, including manufacturing defects, recovery making the device unnecessary, battery depletion, availability of new and better models, and patients asking for a removal. Explantation gives rise to a wide range of ethical issues, but the discussion of these problems is scattered over many clinical disciplines.

METHODS

Information from multiple clinical disciplines was synthesized and analysed in order to provide a comprehensive approach to the ethical issues involved in the explantation of medical implants.

RESULTS

Discussions and recommendations are offered on pre-implantation information about a possible future explantation, risk-benefit assessments of explantation, elective explantations demanded by the patient, explantation of implants inserted for a clinical trial, patient registers, quality assurance, routines for investigating explanted implants, and demands on manufacturers to prioritize increased service time in battery-driven implants and to market fewer but more thoroughly tested models of implants.

CONCLUSION

Special emphasis is given to the issue of control or ownership over implants, which underlies many of the ethical problems concerning explantation. It is proposed that just like transplants, implants that fulfil functions normally carried out by biological organs should be counted as supplemented body parts. This means that the patient has a strong and inalienable right to the implant, but upon explantation it loses that status.

Experience with a standardized protocol to predict successful explantation of left ventricular assist devices

OBJECTIVE

Patients with a continuous-flow left ventricular assist device may show recovery of myocardial function with unloading. Identifying candidates for and predicting clinical and hemodynamic stability after left ventricular assist device explantation remain challenging.

METHODS

Retrospective analysis of patients who underwent evaluation for left ventricular assist device explantation following a standardized protocol from January 2016 to March 2020. Patients who met screening criteria underwent echocardiography under "baseline," "minimal net flow," and "pump stop" conditions. If the protocol criteria were met, right heart catheterization with left ventricular assist device stoppage and occlusion of the outflow graft with a balloon catheter were performed. In patients with pulmonary capillary wedge pressure less than 16 mm Hg, explantation was performed under "pump stop" conditions.

RESULTS

A total of 544 patients were screened. Of these, 57 (10.5%) underwent a total of 73 echocardiography under "baseline" "minimal net flow" and "pump stop" conditions and 46 underwent left ventricular assist device stoppage and occlusion of the outflow graft with balloon catheter maneuvers. Complications during the procedure were rare. Ultimately, 21 patients (3.9%) underwent explantation. The left ventricular ejection fraction at baseline was 55.5% ± 6.5%. The mean pulmonary capillary wedge pressure was 8.1 ± 2.6 mm Hg and increased to 10.7 ± 2.9 mm Hg under left ventricular assist device stoppage and occlusion of the outflow graft with a balloon catheter. A nonischemic cause of cardiomyopathy was more likely to be found in patients who underwent explantation (20/21 patients [95%], P = .020). The survival 1 year after explantation was 95.2%, with 1 death occurring 222 days after left ventricular assist device explantation. At follow-up (median 24.9 months [interquartile range, 16.4-43.1 months]), patients were in New York Heart Association class 1 (61.9%), 2 (28.6%), and 3 (9.5%).

CONCLUSIONS

Our 4-year experience with a standardized protocol for left ventricular assist device explantation showed a low rate of adverse events. If all criteria are met, explantation can be performed safely and with an excellent survival and functional class.

Left ventricular assist device recovery: does duration of mechanical support matter?

Heart failure is a widespread condition in the United States that is predicted to significantly increase in prevalence in the next decade. Many heart failure patients are given a left ventricular assist device (LVAD) while they wait for a heart transplant, while those that are not able to undergo a heart transplant may be given an LVAD permanently. However, past studies have observed a small subset of heart failure patients that recovered cardiac function of their native heart after being placed on an LVAD. As a result, some patients have been able to have their LVAD explanted and no longer needed a heart transplant. In this review, we analyzed the data of 15 studies that observed recovery of cardiac function in LVAD patients in order to investigate the effects that duration of LVAD support has on patient outcomes. From our review, we identified that there may be negative consequences of prolonged duration of mechanical support such as myocardial atrophy and abnormal calcium cycling as well as circumstances that may allow for a longer duration of LVAD support such as in patients using a continuous-flow LVAD, non-ischemic cardiomyopathy patients, and the specific pharmacological therapy.

Review and reflections about pulsatile ventricular assist devices from history to future: concerning safety and low haemolysis-still needed

Since the first use of a ventricular assist device in 1963 many extracorporeal and implantable pulsatile blood pumps have been developed. After the invention of continuous flow blood pumps the implantable pulsatile pumps are not available anymore. The new rotary pumps spend a better quality of life because many of the patients can go home. Nevertheless, the extracorporeal pulsatile pumps have some advantages. They are low-cost systems, produce less haemolysis and heart-recovery can be tested easily. Pump failure is easy to realize because the pumps can be observed visually. Pump exchange can be done easily without any chirurgic surgery. As volume displacement pumps they can produce high blood pressure, so they are the only ones suitable for pediatric patients. Therefore, they are indispensable for clinical use today and in the future. In this work, nearly all pulsatile blood pumps used in clinical life are described.

Utilization and Outcomes of Temporary Mechanical Circulatory Support for Graft Dysfunction After Heart Transplantation

Graft dysfunction is the main cause of early mortality after heart transplantation. In cases of severe graft dysfunction, temporary mechanical circulatory support (TMCS) may be necessary. The aim of this systematic review was to examine the utilization and outcomes of TMCS in patients with graft dysfunction after heart transplantation. Electronic search was performed to identify all studies in the English literature assessing the use of TMCS for graft dysfunction. All identified articles were systematically assessed for inclusion and exclusion criteria. Of the 5,462 studies identified, 41 studies were included. Among the 11,555 patients undergoing heart transplantation, 695 (6.0%) required TMCS with patients most often supported using venoarterial extracorporeal membrane oxygenation (79.4%) followed by right ventricular assist devices (11.1%), biventricular assist devices (BiVADs) (7.5%), and left ventricular assist devices (LVADs) (2.0%). Patients supported by LVADs were more likely to be supported longer (p = 0.003), have a higher death by cardiac event (p = 0.013) and retransplantation rate (p = 0.015). In contrast, patients supported with BiVAD and LVAD were more likely to be weaned off support (p = 0.020). Overall, no significant difference was found in pooled 30 day survival (p = 0.31), survival to discharge (p = 0.19), and overall survival (p = 0.51) between the subgroups. Temporary mechanical circulatory support is an effective modality to support patients with graft dysfunction after heart transplantation. Further studies are needed to establish the optimal threshold and strategy for TMCS and to augment cardiac recovery and long-term survival.

Left ventricular assist device-induced reverse remodeling: it's not just about myocardial recovery

INTRODUCTION

The abnormal structure, function and molecular makeup of dilated cardiomyopathic hearts can be partially normalized in patients supported by a left ventricular assist device (LVAD), a process called reverse remodeling. This leads to recovery of function in many patients, though the rate of full recovery is low and in many cases is temporary, leading to the concept of heart failure remission, rather than recovery. Areas covered: We summarize data indicative of ventricular reverse remodeling, recovery and remission during LVAD support. These terms were used in searches performed in Pubmed. Duplication of topics covered in depth in prior review articles were avoided. Expert commentary: Although most patients undergoing mechanical circulatory support (MCS) show a significant degree of reverse remodeling, very few exhibit sufficiently improved function to justify device explantation, and many from whom LVADs have been explanted have relapsed back to the original heart failure phenotype. Future research has the potential to clarify the ideal combination of pharmacological, cell, gene, and mechanical therapies that would maximize recovery of function which has the potential to improve exercise tolerance of patients while on support, and to achieve a higher degree of myocardial recovery that is more likely to persist after device removal.