Invited commentary

Abstract

The Fontan circulation has undergone important technical changes throughout the years. The right atrium to pulmonary artery (PA) connection has made place for the total cavopulmonary connection (TCPC), first of the lateral tunnel type and thereafter of the extracardiac conduit type. As the Fontan circulation has no right-sided ventricular driving force, all situations that cause energy loss should be avoided. The flow path must be streamlined as much as possible. Collision of caval vein flows, sharp bends, ridges, and expansions result in energy losses. A T-junction of the lateral tunnel or the extracardiac conduit and the PA is inferior in terms of energy preservation than a junction that is more curved toward one PA and thus more streamlined. In vitro models and computational fluid dynamics (CFD) studies have supported and stimulated the ongoing surgical improvements of the Fontan circulation. Several groups (Bove, de Leval and coworkers, Yoganathan and coworkers) have been working in this field for many years. They have demonstrated that an extracardiac TCPC with the inferior vena cava flow more directed toward the left PA is theoretically the optimal situation with the least loss of kinetic energy. In the article by Soerensen and colleagues [1Soerensen D.D. Pekkan K. de Zélicourt D. et al.Introduction of a new optimized total cavopulmonary connection.Ann Thorac Surg. 2007; 83: 2182-2190Abstract Full Text Full Text PDF PubMed Scopus (88) Google Scholar], further improvements of the cavopulmonary connections are presented. An innovative model of bifurcated caval veins connecting equally to both PAs is even more streamlined than the now best available technique, which is an extracardiac TCPC with offsetting of the vena cava to PA connections. The authors have demonstrated with the use of in vitro studies and CFD calculations that their prototype has lower energy losses while an even distribution of inferior caval flow to both PAs (hepatic factor) is preserved. The advantages of this model become even more evident when higher exercise conditions are mimicked by increasing the flows. Although the bifurcated vena cava model may be superior in terms of energy preservation, the road toward clinical implication is long and full of obstacles. Will it be easy to perform this procedure in a young child? Will the risk of thrombosis be increased? What will happen with growth? These are just some of the questions that immediately arise. However, as the theoretical advantages are evident, these obstacles should be considered as challenges for further study. Introduction of a New Optimized Total Cavopulmonary ConnectionThe Annals of Thoracic SurgeryVol. 83Issue 6PreviewSeveral variations of the total cavopulmonary connection (TCPC) have been investigated for favorable fluid mechanics and flow distribution. This study presents a hemodynamically optimized TCPC configuration code-named “OptiFlo.” Featuring bifurcated vena cava (superior venacava to inferior vena cava SVC/IVC), it was designed to lower the fluid mechanical power losses in the connection and to ensure proper hepatic blood perfusion to both lungs. Full-Text PDF