Initial Clinical Experience of Total Cardiac Replacement with Dual Heartmate-II^® Axial Flow Pumps for Severe Biventricular Heart Failure

Introduction

Continuous flow pumps are commonly used to support patients with acute cardiogenic shock and are increasingly used for chronic support in heart failure patients. In the past, pulsatile long-term left ventricular assist devices (LVADs), such as the Novacor and HeartMate-I, provided adequate cardiac support yet they were subject to complications including eventual device failure and infections. With improvements in technology and migration towards axial or continuous flow devices, device miniaturization has become possible, thereby leading to improved anatomical fitting, less vibration and driving noise, and more efficient power consumption. Furthermore, device durability, anti-thrombogenicity, and physiological adaptation to continuous flow pumps appear to be clinically feasible not only for bridge-to-transplant but also for extended longer-term support, namely “destination therapy.”^{1, 2}

In cases of severe biventricular heart failure, right heart support may be required in addition to left heart support. Using a biventricular assist device (BiVAD) to treat biventricular heart failure is one reasonable option;³ however, its clinical feasibility remains controversial.⁴ Another acceptable option for treating biventricular heart failure is total cardiac replacement with a total artificial heart (TAH).⁵ According to clinical results reported by the INTERMACS Study group, the Syncardia pulsatile TAH (Syncardia Systems, Inc., Tucson, AZ, USA) whose implantation resulted in lower postoperative complications and better bridge-to-transplant rates compared to conventional BiVAD implants.⁶

As a similar technology transition from pulsatile to nonpulsatile LVAD, nonpulsatile mechanical circulatory support may be applicable for total cardiac replacement as well, i.e., continuous flow TAH. Unlike the conventional pulsatile TAH driven by pneumatic compression, a continuous flow total artificial heart (CFTAH) would generate absolutely no pulsatility at all. To bring CFTAH into the clinical arena, flow control including the right and left flow balance, inflow suction prevention, and overall physiological adaptation are still remaining issues to be solved.⁷ Dr. O.H. Frazier (Texas Heart Institute, Houston, TX) reported the first animal study experiences using a CFTAH implant as a total heart replacement — with two HeartMate II^® axial flow LVADs — in 2009, which followed a study using dual Jarvik 2000 pumps in 2005.^{8, 9} The animals implanted with the CFTAH in these studies maintained normal physiological parameters for up to seven weeks following device implant. These earlier results were encouraging and suggested the potential future role of a CFTAH for treating biventricular heart failure.

This case report describes our initial clinical experience of total cardiac replacement (complete resection of the heart) with dual HeartMate II^® (HM II) axial flow pumps (Thoratec Corporation, Pleasanton, CA, USA) for treating severe biventricular heart failure.