Fontan Procedure in Single Ventricle Patients: Identifying and managing the failing Fontan circulation

Abstract

The introduction of the strategy of staged surgical palliation, with the Fontan operation as the final stage, has enabled the survival of almost five generations of children born with congenital heart defects that result in a functional single ventricle. However, as these survivors reach adulthood, it has become increasingly apparent that they will likely face deterioration of their circulation over time, leading to premature attrition. Despite so, their long-term prognosis is poorly delineated and the process of late Fontan failure poorly understood, which therefore prevents effective intervention.

This project aims to expand the overall understanding of the process of late Fontan failure in patients living with a Fontan circulation. It will allow for better risk stratification of the surviving population through the identification of important predictors of late Fontan failure and death in this population. It will delineate the roles of surgical intervention including Fontan conversion and use of mechanical circulatory support in the Fontan circulation. The impact of arrhythmia and permanent pacing on Fontan physiology will also be explored. Lastly, we will evaluate the mechanisms of late death in the Fontan population, to identify any modifiable factors that may help prevent late attrition.

This thesis will demonstrate that: (i) Majority of patients living with an atriopulmonary (AP) Fontan remain alive with preserved function in the 2nd-3rd decades post Fontan completion (ii) Fontan conversion is a viable surgical option for patients with an AP Fontan when recommended in a timely manner. (iii) Permanent ventricular pacing is likely detrimental to Fontan physiology and may lead to poorer late survival. (iv) The long-term transplant-free survival of contemporary patients living with a Fontan circulation will likely be determined by the management of Fontan-related complications, and (v) patients with a lateral tunnel (LT) or extracardiac conduit (ECC) Fontan circulation with underlying cardiac deficits should be considered for reintervention to avoid late death secondary to Fontan circulatory failure.

It is through growth in our understanding of the pathophysiology of late Fontan failure that will permit us to provide the necessary care and infrastructure for these surviving patients to live their best lives.