What Did We Learn about VADs in 2022?

This is our 9th annual literature review on mechanical circulatory support devices. Our previous reports were well received by the readers. In this paper, we summarized the most interesting and important, from our standpoint, publications from 2022. There may be some slight overlap with the end of 2021 because some papers were published online first, and the year of the publication changed when they became available in print. For the sixth time, we wrote a section on extracorporeal membrane oxygenation (ECMO) which primarily addresses new developments in veno-arterial ECMO. Readers who wish to supplement this review, argue with the author’s statements or express their opinions are encouraged to do so by sending letters to the editor at [email protected]

An evaluation of continuous-flow left ventricular assist devices and the incidence of stroke in patients awaiting heart transplantation

Continuous-flow left ventricular assist devices provide mechanical circulatory assistance for patients suffering from end-stage heart failure that are awaiting or ineligible for heart transplantation. Although actuarial survival and quality of life with these devices is comparable to allograft transplant, they are associated with severe adverse events, including cerebrovascular accidents. Recent advances in continuous-flow technology aim to mitigate the risk of stroke by including design features that minimize flow stasis, turbulence and endothelial dysfunction, as well as promote near-normal pulse pressures. The proposed study is a multicenter, prospective, randomized clinical trial that aims to compare the stroke-free survival and associated incidence and risk of cerebrovascular accidents between three continuous-flow left ventricular assist devices in patients with refractory, end-stage heart failure planning to undergo bridge-to-transplant or destination therapy. Patients will be randomized to receive one of three devices (HeartMate II, Thoratec Corporation, Pleasanton, CA; HeartWare HVAD, HeartWare International Inc., Framingham, MA; HeartMate III, Thoratec Corporation, Pleasanton, CA). Patients will be monitored for stroke-free survival and incidence of cerebrovascular accident for 24 months post-implantation. Investigators will compare stroke-free survival with Kaplan-Meier survival curves and log-rank testing; in addition, investigators will examine each device’s level of risk for causing a cerebrovascular accident with chi square and odds ratio analysis. The data from this study will be used to guide treatment paradigms, device assignment and future development of technologies that mitigate stroke risk in this high-risk population

Fluid Dynamics in the HeartMate 3: Influence of the Artificial Pulse Feature and Residual Cardiac Pulsation

Ventricular assist devices (VADs), among which the HeartMate 3 (HM3) is the latest clinically approved representative, are often the therapy of choice for patients with end‐stage heart failure. Despite advances in the prevention of pump thrombosis, rates of stroke and bleeding remain high. These complications are attributed to the flow field within the VAD, among other factors. One of the HM3’s characteristic features is an artificial pulse that changes the rotor speed periodically by 4000 rpm, which is meant to reduce zones of recirculation and stasis. In this study, we investigated the effect of this speed modulation on the flow fields and stresses using high‐resolution computational fluid dynamics. To this end, we compared Eulerian and Lagrangian features of the flow fields during constant pump operation, during operation with the artificial pulse feature, and with the effect of the residual native cardiac cycle. We observed good washout in all investigated situations, which may explain the low incidence rates of pump thrombosis. The artificial pulse had no additional benefit on scalar washout performance, but it induced rapid variations in the flow velocity and its gradients. This may be relevant for the removal of deposits in the pump. Overall, we found that viscous stresses in the HM3 were lower than in other current VADs. However, the artificial pulse substantially increased turbulence, and thereby also total stresses, which may contribute to clinically observed issues related to hemocompatibility

A Historical Review of Mechanical Circulatory Support

Meaningful and contemporary data regarding the clinical use of mechanical circulatory support (MCS) is founded on the work conducted in the 1950s when a “heart-lung” machine was incorporated to provide support during surgical interventions. Following this milestone, the need to support artificial circulation in patients with heart failure initiated an investigational and legislative collaboration to implement the mission-oriented Artificial Heart Program in the United States during the 1960s. In the subsequent decades, technological discoveries have integrated a series of mechanical systems employed as therapeutic options for short- and long-term artificial circulation in children and adults with advanced heart failure. Since their clinical application, MCS devices have been employed as a bridge to transplantation in over 4000 patients globally. In recent years, the adverse effects and economic burden of MCS have been counterbalanced by the harmonization of therapeutic protocols, the inclusion of multidisciplinary insight, and the allowance of families and patients to participate in shared decision making to address candidacy. In this chapter, we provide a review of the historical aspects of MCS, a therapeutic option for overcoming complexities encountered in reestablishing adequate hemodynamic states and providing a reasonable quality of life

The Effects of Ambulatory Accelerations on the Stability of a Magnetically Suspended Impeller for an Implantable Blood Pump

National Institute for Health Research. Grant Number: II-LB-1111-2000

Heart Transplantation in the Era of the Left Ventricular Assist Devices

Orthotopic heart transplant is recognized as the gold standard for the treatment of end-stage heart disease. However, there is a perennial shortage of donor organs. Left ventricular assist devices (LVAD) represent a revolutionary tool for temporizing heart failure that is refractory to medical management until a suitable organ becomes available. This review highlights the LVAD as a tool for bridging to transplant. The history of the LVAD and its use in heart transplantation is described, as well as the current indications for use in the general heart transplant candidate as well as for selected subpopulations. It also highlights the major complications of LVAD use, advancements in the field, and selected current controversies related to the LVAD as bridge-to-transplant therapy

Cellular and Molecular Mechanisms Activated by a Left Ventricular Assist Device

Left ventricular assist devices (LVADs) represent the final treatment for patients with end-stage heart failure (HF) not eligible for transplantation. Although LVAD design has been further improved in the last decade, their use is associated with different complications. Specifically, inflammation, fibrosis, bleeding events, right ventricular failure, and aortic valve regurgitation may occur. In addition, reverse remodeling is associated with substantial cellular and molecular changes of the failing myocardium during LVAD support with positive effects on patients’ health. All these processes also lead to the identification of biomarkers identifying LVAD patients as having an augmented risk of developing associated adverse events, thus highlighting the possibility of identifying new therapeutic targets. Additionally, it has been reported that LVAD complications could cause or exacerbate a state of malnutrition, suggesting that, with an adjustment in nutrition, the general health of these patients could be improved