Blood flow dynamics in the total cavopulmonary connection long-term after Fontan completion

Abstract

Long-term survival for univentricular heart patients with a Fontan circulation is nowadays excellent, with the majority of patients expecting to reach adulthood. Nevertheless, a general attrition rate remains present and the majority of Fontan patients will be faced with significant morbidity. However, no Fontan patient is the same and there is a need for better understanding which patients will do worse, ideally by (early) identification of adverse factors that can be optimized. In this thesis, the role of flow efficiency in the TCPC was thoroughly investigated leading to multiple new insights. A novel three-dimensional blood flow MR sequence (3D flow MRI) was developed and shown to be superior to conventional 2D and 4D flow MRI sequences which could potentially lead to a more widespread use. Adverse flow patterns associated with reduced flow efficiency were shown at multiple areas within the TCPC which were related to adverse energetics. Increased 4D flow MRI derived energetics in turn are associated with reduced exercise capacity and increased levels of liver fibrosis/venous congestion. A focus on conduit size adequacy demonstrated that the currently used 16-20mm extracardiac conduits become undersized for teenage and adolescent Fontan patients. Undersized conduits proved to be an important factor leading to reduced flow efficiency, especially during exercise conditions. Achievement of optimal blood flow in Fontan patients may ultimately lead to improved long-term outcome.