The Fontan is the final common pathway for most single ventricle lesions. It is not a durable circulation and many Fontan patients eventually present for advanced heart failure therapies including mechanical circulatory support. While there have been advancements in available durable devices, many pediatric patients have size, anatomical, and physiologic constraints that make placement of adult ventricular assist devices challenging. And, Fontan failure comes in different varieties, including failure with preserved systolic function. This subset of patients requires either a subpulmonary assist device or a total artificial heart. Unique operative maneuvers, including atrial cannulation and atrioventricular valve manipulation have allowed many failing Fontan patients to be bridged to transplant after recovery of end-organ dysfunction and improved nutrition. The Advanced Cardiac Therapies Improving Outcomes Network is a multicenter learning network of pediatric hospitals implanting, managing, and studying ventricular assist devices in children and adults with congenital heart disease. This network is advancing the knowledge of outcomes and approaches to mechanical circulatory support in those with congenital heart disease, including Fontans. The congenital heart disease community continues to work toward and hope for a smaller durable device that will help this complex cohort of patients.