Creation of the Fontan circulation in sheep: a survival model

Patients with a single ventricle survive thanks to the Fontan palliation. Nevertheless, there is a growing number of Fontan patients with progressive heart failure. To validate therapeutic options in these patients, we developed a chronic Fontan large animal model.

A Fontan circulation was surgically created in 15 sheep. The superior vena cava was anastomosed end-to-side to the pulmonary artery. The inferior vena cava was connected to the pulmonary artery by an ePTFE conduit, and the inferior vena cava-right atrium junction was ligated.

Total cavopulmonary connection was successfully performed in all 15 animals. After creation of the Fontan circulation, central venous pressure increased from 4 [interquartile range (IQR) 3-6] mmHg to 16 (IQR 14-17) mmHg, mean arterial blood pressure decreased from 68 (IQR 54-75) mmHg to 52 (IQR 50-61) mmHg and cardiac output decreased from 5.1 (IQR 4.6-6.8) l/min to 1.7 (IQR 1.3-2.7) l/min. Five animals were electively sacrificed after a follow-up period of 21 weeks.

These results demonstrate that it is feasible to create a chronic animal model with unsupported Fontan circulation. This animal model not only opens perspectives to investigate the pathophysiology of the failing Fontan circulation, but also provides the possibility to study therapeutic options such as the effect of mechanical circulatory support in the failing Fontan physiology.