AN IMPLANTABLE BLOOD PUMP FOR ADULT CONGENITAL HEART DISEASE PATIENTS WITH A FAILED FONTAN CIRCULATION

Background: For children born with congenital cardiac malformations resulting in a single functional ventricle, the Fontan operation has provided palliation such that children are increasingly surviving into adulthood. The Fontan circulation allows systemic venous blood to bypass the pulmonary ventricle and flow directly into the pulmonary arteries, and it utilizes the functioning single ventricle only to provide the systemic (left-sided) cardiac output. Due to improvements in operative procedures, timing, staging, and management, early mortality is now less than 5% and survival at 20 years is 85%. However, morbidity is significant due to venous congestion and elevated pulmonary vascular resistance, progressive ventricular dysfunction, dysrhythmias, hypoxemia, and protein-losing enteropathy.As more patients with Fontan palliation grow into adulthood, there is an increasing need for means to support patients with failing Fontan physiology. The debilitating nature of Fontan failure, and the onset at a young age, is expected to result in significant healthcare costs. Heart transplantation is currently the only viable option, but the morbidity of the failing Fontan makes these patients suboptimal candidates for heart transplantation, and competition for available donor organs remains a limitation.Objective: The objective of this project is to develop a small implantable blood pump, called the Fontan Circulation Assist Device (FCAD), to provide long-term mechanical right heart support for patients who have had the Fontan surgical palliation (primarily for single ventricle congenital heart defects) and who exhibit progressive Fontan failure.Rationale: Implantable mechanical blood pumps are increasingly used to provide long-term support for the failing left ventricle in adults with end-stage heart failure. Referred to as Left Ventricular Assist Devices (LVADs), over 2500 durable LVADs are implanted each year in the United States, with an actuarial survival of 70% at 3 years. We propose to adapt this technology to the specific requirements of the failed Fontan circulation so that patients may return to an active lifestyle and improved quality of life.Uniqueness: There are a number of mechanical blood pumps under development for short-term Fontan support. These are usually catheter-based devices, meaning that a catheter, cable, or drive cable must exit the vena cava, from the femoral or jugular vein. This is acceptable in an acute hospital setting but not as a long-term system. Our group has extensive experience in developing fully implantable blood pump systems, which are powered wirelessly, and designed for multi-year use. The proposed device would be the first blood pump designed for long-term support of the right-sided circulation. The FCAD has two opposing inlet ports for the superior and inferior cavae, and two outlet ports for the left and right pulmonary arteries. Prototypes have been designed, built, and tested. A reduced size pump has also been designed.Impact: Based on the well-documented improvements in quality of life and multi-year survival for patients with LVADs, it is reasonable to expect that similar results can be obtained with the FCAD.Relevance to Fiscal Year 2015 Peer Reviewed Medical Research Program Topic Area: Congenital Heart Disease. Research on the transition of care of congenital heart disease patients from pediatric to adult providers in the Military Health System. Research on the ability of patients with congenital heart disease to join or remain on active duty.Specific Aim 1: Miniaturize and optimize the FCAD with the goals of minimizing hemolysis, thrombosis, pump size, and power consumption. Computational fluid dynamics will be used to evaluate the effect of key design variables on performance, and velocity results will be validated using experimental fluid dynamics. Candidate designs will be built and tested in vitro and in vivo to validate computational results.Specific Aim 2: Validate the biocompatibility of pump designs in vivo in the sheep model. Acute studies and 30-day chronic studies will be used. The primary objective is to assess thrombosis potential, through measurement of coagulation parameters and platelet activation, pump surface analysis, and necropsy.Specific Aim 3: Perform limited reliability assessment with initial in vitro reliability testing of the FCAD pump.