Biventricular Assist Devices: A Technical Review

Shaun D. Gregory, Daniel Timms, Nicholas Gaddum, David G. Mason, John F. Fraser

The optimal treatment option for end stage heart failure is transplantation; however, the shortage of donor organs necessitates alternative treatment strategies such as mechanical circulatory assistance. Ventricular assist devices (VADs) are employed to support these cases while awaiting cardiac recovery or transplantation, or in some cases as destination therapy. While left ventricular assist device (LVAD) therapy alone is effective in many instances, up to 50% of LVAD recipients demonstrate clinically significant postoperative right ventricular failure and potentially need a biventricular assist device (BiVAD). In these cases, the BiVAD can effectively support both sides of the failing heart. This article presents a technical review of BiVADs, both clinically applied and under development. The BiVADs which have been used clinically are predominantly first generation, pulsatile, and paracorporeal systems that are bulky and prone to device failure, thrombus formation, and infection. While they have saved many lives, they generally necessitate a large external pneumatic driver which inhibits normal movement and quality of life for many patients. In an attempt to alleviate these issues, several smaller, implantable second and third generation devices that use either immersed mechanical blood bearings or hydrodynamic/magnetic levitation systems to support a rotating impeller are under development or in the early stages of clinical use. Although these rotary devices may offer a longer term, completely implantable option for patients with biventricular failure, their control strategies need to be refined to compete with the inherent volume balancing ability of the first generation devices. The BiVAD systems potentially offer an improved quality of life to patients with total heart failure, and thus a viable alternative to heart transplantation is anticipated with continued development.