title: Control of respiration-driven retrograde flow in the subdiaphragmatic venous return of the Fontan circulation.
abstract: Respiration influences the subdiaphragmatic venous return in the total cavopulmonary connection (TCPC) of the Fontan circulation whereby both the inferior vena cava (IVC) and hepatic vein flows can experience retrograde motion. Controlling retrograde flows could improve patient outcomes. Using a patient-specific model within a Fontan mock circulatory system with respiration, we inserted a valve into the IVC to examine its effects on local hemodynamics while varying retrograde volumes by changing vascular impedances. A bovine valved conduit reduced IVC retrograde flow to within 3% of antegrade flow in all cases. The valve closed only under conditions supporting retrograde flow and its effects on local hemodynamics increased with larger retrograde volume. Liver and TCPC pressures improved only when the valve leaflets were closed whereas cycle-averaged pressures improved only slightly (<1 mm Hg). Increased pulmonary vascular resistance raised mean circulation pressures, but the valve functioned and cardiac output improved and stabilized. Power loss across the TCPC improved by 12%-15% (p < 0.05) with a valve. The effectiveness of valve therapy is dependent on patient vascular impedance.
authors.affiliation: From the *Mechanical and Bioengineering Engineering, Clemson University, Clemson, South Carolina; †Laboratory of Biological Structure Mechanics, Politecnico di Milano, Milan, Italy; and ‡Cardiothoracic Surgery, Great Ormond Street Hospital for Children, London, United Kingdom.
authors.forename: Marija
authors.initials: M
authors.lastname: Vukicevic
authors.forename: Timothy
authors.initials: T
authors.lastname: Conover
authors.forename: Michael
authors.initials: M
authors.lastname: Jaeggli
authors.forename: Jian
authors.initials: J
authors.lastname: Zhou
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Pennati
authors.forename: Tain-Yen
authors.initials: TY
authors.lastname: Hsia
authors.forename: Richard S
authors.initials: RS
authors.lastname: Figliola
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity; D002417:Cattle; D002648:Child; D005260:Female; D018729:Fontan Procedure; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008955:Models, Cardiovascular; D012119:Respiration