Original Fontan palliation and extracardiac conduit Fontan modification

The Fontan operation involves routing of systemic venous return directly into pulmonary circulation, bypassing the subpulmonary ventricle. The procedure has undergone several modifications since 1971, as illustrated in these schematics: A. The original Fontan procedure, which entailed anastomosis of the distal end of the right pulmonary artery to the superior vena cava; anastomosis of the right atrial appendage to the proximal end of right pulmonary artery by means of an aortic valve homograft; closure of atrial septal defect; insertion of a pulmonary valve homograft into the inferior vena cava; and ligation of the main pulmonary artery. B. Extracardiac conduit Fontan involving anastomosis of a vascular graft between the inferior vena cava and the pulmonary artery, which allows more uniform flow with less turbulence.