The role of continuous flow ventricular assist device for destination therapy in children: Can it work or is it a bridge too far?

Abstract

The field of mechanical circulatory support for children has shown tremendous growth and evolution over the last decade. This is in part due to the worldwide epidemic of heart failure in adults—a prevalence of 23million and counting [1,2] feeding the burgeoningmarket for ventricular assist device (VAD) design and development. Device design in children has been markedly more challenging due to the biotechnical demands of device miniaturization and the limited market field in children compared to adults. Based on most recent data from the International Society of Heart and Lung Transplantation, over 550 children underwent heart transplantation worldwide in 2011, of which 20% required mechanical circulatory support in the form of a VAD or total artificial heart as a bridge to transplantation [3]. This suggests a market for pediatric specific VADs in the hundreds of devices per year, as opposed to the tenfold higher demand for VADs in adults. As such, the substantial growth of pediatric VAD support can be in large part attributed to the adoption of newer generation intracorporeal continuous flow (CF) VADs designed for adults, but small enough for implantation in children and adolescents. The advent of CF VADs is an important milestone in the history of mechanical circulatory support. To fully appreciate the pivotal role of CF VAD in the progression of circulatory support for both children and adults, one must have an understanding of the predecessor devices. The last 40 years has seen 3 generations of VADs. The first generation of implantable VADs were volume displacement pulsatile flow (PF) devices, such as the HeartMate XVE® in 1998 (Thoratec Inc.; Plesanton, California, US). These devices had significant limitations secondary to its large size, need for extensive surgical dissections, poor pumpdurability andhigh thromboembolic, bleeding and infection event rate. Its large size precluded applicability to children. Appreciating the need for long