Generation Ventricular Assist Device Research Articles

Sensorless measurement of biological information in a magnetically levitated artificial heart and its application to QOL improvement technology

Heart disease is the leading cause of death in men and women around the world and it is a significant problem that requires remedy. Heart failure is where the heart is not pumping blood around the body as effectively as it should. Importantly, heart failure does not mean that the heart has stopped working, but it does require support in order to get it working better. Over the past few decades, there have been many innovations to help address the problems with heart failure, including developing ventricular assist devices (VADs). A VAD is a mechanical pump that is placed inside the body to support heart function and blood flow in heart patients. It works by taking blood from a lower chamber in the heart and pumping it to the body and vital organs, in the same way that a healthy heart would. Dr Wataru Hijikata is an expert in mechanical engineering and technology with a focus on healthcare outcomes. He explains that the first generation of VADs was a pulsatile flow type, but because of the complicated mechanical structure, the size of them was large and they had low durability. He notes that the second generation VAD was a continuous flow type. Because the blood flow was generated by the rotation of an impeller, the mechanical structure was simple and the size was small. However, the bearings to support the rotating impeller led to low durability. 'Third generation VADs are continuous flow types with contactless support of the impeller by magnetic bearing or hydrodynamic bearings,' Hijikata outlines. Owing to the contactless support technology, the durability of VADs has been enhanced and the size of the device is small. 'However, while there has been significant progress over the years, VADs are still far from perfect and there is much room for improvement,' he concludes. With that in mind, a team of researchers based at the Department of Mechanical Engineering in the Tokyo Institute of Technology, Japan, is investigating a means of improving VADs.

Third Generation Ventricular Assist Device: Mid-Term Outcomes of the HeartWare HVAD in Pediatric Patients.

The HeartWare HVAD is a small, third generation continuous flow pump that is intracorporeally placed for support of a failing ventricle in adult patients. This device is small in size when compared to other left ventricular assist devices and can therefore be used in smaller sized pediatric patients. We present our initial experience using the HVAD as a bridge to heart transplantation in the pediatric population. We performed a retrospective, single center, nonrandomized review of 17 pediatric patients who underwent HVAD implantation between June 2013 and March 2016. The primary endpoints evaluated in this study were overall survival to heart transplantation, ongoing device support, or death. In this patient cohort, nine (53%) of 17 patients were male. The median age of the patients was 13.4 ± 3.8 (range 5-17) years. The median body surface area was 1.4 ± 0.4(0.7-2) m2 . Etiologies of heart failure requiring HVAD support were dilated cardiomyopathy (n = 8), myocarditis (n = 5) and noncompaction cardiomyopathy (n = 4). The overall mean length of HVAD support was 254 ± 298 (range 2-804) days. A successful outcome (bridge to transplant and ongoing mechanical support) was achieved in 13 patients (76.5%). Of the 13 patients, nine (69.2%) were bridged to heart transplantation and four continue to receive support (30.7%) and are eligible for transplantation. Post-transplant survival has been 100%, with a mean follow-up of 296 ± 264.5 (range 18-785) days. The most common complication was pump thrombosis (23.5%) in follow-up. Four patients (23.5%) experienced no complications. The HVAD continuous flow ventricular assist device can be safely used to bridge pediatric patients to cardiac transplantation. Favorable outcomes of this device are comparable to the adult population. This analysis demonstrated safe and effective implantation of the HVAD System in a child with a BSA of 0.7 m2 .

Pediatric ventricular assist devices.

The domain of pediatric ventricular assist device (VAD) has recently gained considerable attention. Despite the fact that, historically, the practice of pediatric mechanical circulatory support (MCS) has lagged behind that of adult patients, this gap between the two groups is narrowing. Currently, the Berlin EXCOR VAD is the only pediatric-specific durable VAD approved by the U.S Food and Drug Administration (FDA). The prospective Berlin Heart trial demonstrated a successful outcome, either bridge to transplantation (BTT), or in rare instances, bridge to recovery, in approximately 90% of children. Also noted during the trial was, however, a high incidence of adverse events such as embolic stroke, bleeding and infection. This has incentivized some pediatric centers to utilize adult implantable continuous-flow devices, for instance the HeartMate II and HeartWare HVAD, in children. As a result of this paradigm shift, the outlook of pediatric VAD support has dramatically changed: Treatment options previously unavailable to children, including outpatient management and even destination therapy, have now been becoming a reality. The sustained demand for continued device miniaturization and technological refinements is anticipated to extend the range of options available to children-HeartMate 3 and HeartWare MVAD are two examples of next generation VADs with potential pediatric application, both of which are presently undergoing clinical trials. A pediatric-specific continuous-flow device is also on the horizon: the redesigned Infant Jarvik VAD (Jarvik 2015) is undergoing pre-clinical testing, with a randomized clinical trial anticipated to follow thereafter. The era of pediatric VADs has begun. In this article, we discuss several important aspects of contemporary VAD therapy, with a particular focus on challenges unique to the pediatric population.

Is Implantation of a Left Ventricular Assist Device in Patients With Critical or Impending Cardiogenic Shock an Absolute Contraindication? Looking Back at Our Past Experience Trying to Identify Contraindicative Risk Factors

Poor survival has been demonstrated after ventricular assist device (VAD) implantation for Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) profile 1 and 2 patients compared with more stable levels. However, risk factors within this high-risk cohort have not been determined so far. The aim of the present study was to identify risk factors associated with this very high mortality rate. Between February 1993 and January 2013, 298 patients underwent VAD implantation in our institution. One hundred nine patients were in INTERMACS level 1 and 49 patients were in INTERMACS level 2 and were therefore defined as hemodynamically critical (overall 158 patients). Assist devices implanted were: HVAD HeartWare n = 18; Incor n = 11; VentrAssist n = 2; DeBakey n = 22; and pulsatile systems n = 105. After cumulative support duration of 815.35 months, Kaplan-Meier analysis revealed a survival of 63.9, 48.8, and 40.3% at 1, 6, and 12 months, respectively. Cox regression analyses identified age > 50 (P = 0.001, odds ratio [OR] 2.48), white blood cell count > 13.000/μL (P = 0.01, OR 2.06), preoperative renal replacement therapy (P = 0.001, OR 2.63), and postcardiotomy failure (P < 0.001, OR 2.79) as independent predictors of mortality. Of note, last generation VADs were not associated with significantly better 6-month survival (P = 0.59). Patients without the aforementioned risk factors could yield a survival of 79.2% at 6 months. This single-center experience shows that VAD implantation in hemodynamically unstable patients generally results in poor early outcome, even in third-generation pumps. However, avoiding the aforementioned risk factors could result in improved outcome.

One Hundred and Counting: A Centre Specific Report on Outcomes of Old Generation Vs. New Generation Ventricular Assist Devices

Since May 2002, St. Paul's Hospital has implanted 121 ventricular assist devices (VADs) into 113 patients. February 2008 saw the implementation of the new generation of continuous flow VADs which were smaller, more reliable and easier for patients to use. We will present an overview of outcomes seen in our centre to date and provide some insights that may stimulate future nursing research.

Design Method of a Foldable Ventricular Assist Device for Minimally Invasive Implantation

To date, ventricular assist devices (VADs) have become accepted as a therapeutic solution for end-stage heart failure patients when a donor heart is not available. Newer generation VADs allow for a significant reduction in size and an improvement in reliability. However, the invasive implantation still limits this technology to critically ill patients. Recently, expandable/deployable devices have been investigated as a potential solution for minimally invasive insertion. Such a device can be inserted percutaneously via peripheral vessels in a collapsed form and operated in an expanded form at the desired location. A common structure of such foldable pumps comprises a memory alloy skeleton covered by flexible polyurethane material. The material properties allow elastic deformation to achieve the folded position and withstand the hydrodynamic forces during operation; however, determining the optimal geometry for such a structure is a complex challenge. The numerical finite element method (FEM) is widely used and provides accurate structural analysis, but computation time is considerably high during the initial design stage where various geometries need to be examined. This article details a simplified two-dimensional analytical method to estimate the mechanical stress and deformation of memory alloy skeletons. The method was applied in design examples including two popular types of blade skeletons of a foldable VAD. Furthermore, three force distributions were simulated to evaluate the strength of the structures under different loading conditions experienced during pump operation. The results were verified with FEM simulations. The proposed two-dimensional method gives a close stress and deformation estimation compared with three-dimensional FEM simulations. The results confirm the feasibility of such a simplified analytical approach to reveal priorities for structural optimization before time-consuming FEM simulations, providing an effective tool in the initial structural design stage of foldable minimally invasive VADs.

Ventricular assist devices: initial orientation.

Ventricular assist device (VAD) technology has come from large pulsatile-flow devices with a high rate of technical malfunctions to small continuous flow (cf) devices. Mechanical circulatory support (MCS) systems may be used as short-, mid- or long-term support. Especially if mid- or long-term support is anticipated left VADs (LVADs) have been reported with excellent one and two year survival rates and improved quality of life (QoL). Timing of implantation, patient selection, assessing function of the right ventricular and surgical considerations regarding surgical access side, valve pathology and exit side of the percutaneous lead remain crucial issues for the outcome. In contrast VADs designed for children especially for all age groups, are still underrepresented but increased experience with existing pediatric VADs as well as introduction of second and third generation VADs into in the pediatric age group, offer new perspectives.

Executive Summary for the National Heart, Lung, and Blood Institute Working Group on Next Generation Ventricular Assist Devices for Destination Therapy

Executive Summary for the National Heart, Lung, and Blood Institute Working Group on Next Generation Ventricular Assist Devices for Destination Therapy

Implantation Technique for the HeartSaver Left Ventricular Assist Device

Implantation Technique for the HeartSaver Left Ventricular Assist Device