Early Feasibility Testing and Engineering Development of the Transapical Approach for the HeartWare MVAD Ventricular Assist System

Abstract

Implantation of ventricular assist devices (VADs) for treatment of end-stage heart failure (HF) falls decidedly short of clinical demand, which exceeds 100,000 HF patients per year. VAD implantation often requires major surgical intervention with associated risk of adverse events and long recovery periods. To address these limitations, HeartWare, Inc. (Miami Lakes, FL) has developed a platform of miniature ventricular devices with progressively reduced surgical invasiveness and innovative patient peripherals. One surgical implant concept is a transapical version of the miniaturized left ventricular assist device (MVAD). The HeartWare MVAD Pump® is a small, continuous flow, full-support device that has a displacement volume of 22mL. A new cannula configuration has been developed for transapical implantation, where the outflow cannula is positioned across the aortic valve. The two primary objectives for this feasibility study were to evaluate anatomic fit and surgical approach and efficacy of the transapical MVAD configuration. Anatomic fit and surgical approach were demonstrated using human cadavers (n=4). Efficacy was demonstrated in acute (n =2) and chronic (n = 1) bovine model experiments and assessed by improvements in hemodynamics, biocompatibility, flow dynamics, and histopathology. Potential advantages of the MVAD Pump include flow support in the same direction as the native ventricle, elimination of cardiopulmonary bypass, and minimally-invasive implantation.

Interaction of a Transapical Miniaturized Ventricular Assist Device With the Left Ventricle: Hemodynamic Evaluation and Visualization in an Isolated Heart Setup

“…A tMVAD (HeartWare Inc., Miami Lakes, FL, USA) was used in this study (3,4). The MVAD is a small, continuous axial-flow, full-support device with a volume of 22 mL.…”

“…The investigation of this interaction is usually performed in silico, in vitro, and in vivo with acute and chronic animal models (1)(2)(3)(4)(5). The investigation of this interaction is usually performed in silico, in vitro, and in vivo with acute and chronic animal models (1)(2)(3)(4)(5).…”

Dynamic measurement of centering forces on transvalvular cannulas

“…24,25 However, miniaturization of VADs allows direct implantation into the cardiac chamber and allows the use of these pumps as conventional VADs with the outflow cannula passing through the aortic valve. 6 For transvalvular devices, the interaction with the aortic valve and especially centering in the aortic orifice seems to play an important role. In the centric position, the valve leaflets equally seal against the cannula, whereas an eccentric position of the cannula can push a leaflet to the side of the aorta and result in an increased mechanical load on the leaflets and backflow.…”

“…These devices typically pump blood through a cannula placed across the functioning aortic valve, also if the pump itself is placed extracorporeally . However, miniaturization of VADs allows direct implantation into the cardiac chamber and allows the use of these pumps as conventional VADs with the outflow cannula passing through the aortic valve …”

State of the Art of Mechanical Circulatory Support

“…It has a wide-blade design to reduce shear force on blood components while providing 1 to 7 L/min of blood flow. 35 This device can be implanted through various minimally invasive approaches that do not necessitate median sternotomy, 36 including a right mini-thoracotomy with placement of a novel inflow cannula through the superior pulmonary vein, into the left atrium, and through the mitral valve into the LV. 37 Clinical trials are anticipated in the near future and are hoped to provide further tools in the armamentarium against end-stage heart failure.…”