Adult patients with univentricular physiology after Fontan palliation: prevalence and percutaneous closure of veno-venous collaterals

Abstract Background The Fontan operation resulted in improved survival of patients with congenital heart defects not equipped to sustain a biventricular circulation. Long-term complications are common. Veno-venous collaterals (VVC) can have both potentially beneficial and adverse physiological effects. The aim of this study was to evaluate the prevalence of VVC in adult Fontan patients and describe the percutaneous treatment strategy and the short term follow-up. Methods In this single-centre retrospective observational cohort study, consecutive adult Fontan patients under follow-up in the period between 2017-2023 were included. Results From a cohort of 51 Fontan patients, 14 (28%) underwent a percutaneous closure of VVC (71% female, mean age at intervention 24±4 years). Mean follow-up duration was 2.2±1.1 years. Indications were symptoms and/or significant exercise-related hypoxia. Ten patients (71%) had a systemic left ventricle, and 79% had an extracardiac tunnel (median conduit size 16[16-20]mm). Mean Fontan pressure was 10±4mmHg. Seven patients (50%) had Fontan-associated liver disease. A total of 24 VVC were occluded using coils and/or vascular plugs. No periprocedural complications occurred. The VVC originated from right-sided tributaries of the vena cava inferior (36%), superior vena cava (28%) or both (36%), with the majority draining directly into the pulmonary venous circulation. Eight patients (57%) reported a reduction of symptoms. Mean saturation in rest improved significantly, yet saturation during maximal exercise remained unchanged (94±3 to 97±3%, p=0.002 and 88±3 to 91±4%, p=0.103, respectively). Conclusions VVC are highly prevalent in the adult Fontan population and typically connect the right-sided tributaries of the vena cava inferior and/or superior with the pulmonary veins. Low Fontan pressures do not exclude the presence of VVC. Percutaneous closure of VVC is technically feasible and safe and is associated with reduction of symptoms and a significant rise in resting peripheral oxygen saturation. These results warrant further studies.