Failing Fontan cardiovascular support: Review

Abstract

Background Although all congenital heart defects (CHD) present unique challenges, univentricular CHD are especially challenging given the difficulty of passively perfusing pulmonary blood flow. Three surgical procedures are required within the first years of life, with the final completing a Fontan circulation in which the inferior vena cava is connected to the pulmonary artery and previously connected superior vena cava. This allows passive venous return to the pulmonary circulation then flow into the single ventricle for systemic circulation. Methods Although a Fontan provides successful palliation for two to three decades, many complications can arise as pulmonary resistance must remain low to allow adequate forward flow. Eventually, the failing Fontan circulation requires temporary support as the patient awaits a heart transplant. We reviewed PubMed, Google Scholar, and U. Kentucky library for different techniques evaluated to support a failing Fontan circulation. Results Multiple technologies have been developed as a bridge to transplant to decrease morbidity. Innovative types of extracorporeal membrane oxygenation, ventricular assist devices, and total artificial hearts have been attempted in laboratory settings as well as in Fontan patients with varying degrees of success. This article emphasizes the strengths and weaknesses of each technology in the context of Fontan physiology. Conclusion The end game for these patients remains a heart transplant. Without easy access to donors, each of the options discussed is a potential bridge to limit morbidity and mortality until a suitable donor heart becomes available.

Pediatric Ventricular Assist Devices

“…Once failure symptomatology starts, transplant waitlist mortality is high [6]. Several limited options exist for supporting failing Fontan physiology including VAD implantation [6,26].…”

“…Also, the HeartMate 2 supported a sheep for 2 hours when placed in the cavopulmonary graft. Implantation of the HeartWare HVAD in three Fontan patients for 5 to 9 months were successful bridge to transplant [26]. However, in 2021, the HeartWare device was recalled and not currently available for implantation [5].…”

“…However, in 2021, the HeartWare device was recalled and not currently available for implantation [5]. One case demonstrated the Berlin Heart provided biventricular support for a failing Fontan circulation [26]. HeartMate 3 implantation in a CHD Fontan patient is usually performed after multiple previous staged palliative operations [6].…”

“…One of the physiologic challenges after insertion of VAD into the ventricle is off-loading, but can also concomitantly increase Fontan pressures, which can lead to a worsening clinical situation. It does appear that continuous devices are more beneficial than pulsatile devices given the reliance of the circulation on passive pulmonary flow [26]. Careful consideration is needed of the underlying etiology for a failing Fontan, such as ventricular failure, elevated pulmonary artery pressures, or enddiastolic pressures.…”