Bleeding in continuous flow left ventricular assist device recipients: an acquired vasculopathy?
Durable mechanical circulatory support (MCS) has long held appeal as a solution to the growing imbalance between donor availability for heart transplantation and the increasing population of advanced heart failure (HF) as—unlike donor organs—it can be produced and utilized on demand. Despite steady and at times remarkable progress over the past half century, MCS did not become a reality until the advent of the continuous flow left ventricular assist devices (CF LVAD) in the early 2000s. It is now clear that CF LVADs improve not only survival but also functional capacity and quality of life in medically refractory HF. This has translated into exponential growth in CF LVAD utilization and for the first time in 2012, this therapy outpaced heart transplantation. While there will be continued refinement to this technology over the coming years, the overall principle will remain unchanged—a rotary pump with only one moving part to propel blood from the ventricle to the aorta. For this reason, the issue of hemocompatibility, i.e., the consequences of blood elements interfacing with the device during transit, will continue to challenge the field. Hemo(mal)compatibility during CF LVAD has to balance two opposing effects: device thrombosis and mucosal bleeding. While device thrombosis in an intravascular cavitary device was predictable and remains of concern, mucosal bleeding during CF LVAD was unanticipated and remains poorly understood.