title: Designing the optimal Total Cavopulmonary Connection: pulsatile versus steady flow experiments.
abstract: BACKGROUND
  The Total Cavopulmonary Connection (TCPC), used for repair of patients with single ventricle physiology, creates a passive system of blood flow into the pulmonary circulation where enhanced energy efficiency may lead to improved long term patient outcomes. Previous numerical and in vitro studies using steady flow have shown that incorporation of SVC (superior vena cava) and IVC (inferior vena cava) offsets lead to decreased energy losses. We hypothesize that the optimal TCPC offset design found in these previous steady flow experiments may not be the optimal design in pulsatile flow situations.
  
  
  METHODS
  3-D finite volume numerical models were used to simulate flow through the total cavopulmonary connection. We ran steady and pulsatile flow experiments through 4 TCPC designs each with different SVC to IVC offsets (0.1/4, 1/2, 1 diameter offsets). The total energy (power) loss for each TCPC model was calculated.
  
  
  RESULTS
  In steady flow experiments, % difference in energy loss between the most optimal and least optimal design was 26%. In contrast, in pulsatile flow experiments the % difference was only 8%.
  
  
  CONCLUSIONS
  Our results demonstrate the improvements in energy loss seen using SVC-IVC offsets in steady flow experiments do not necessarily translate to pulsatile flow situations. Overall there was lower differences in efficiency between all TCPC designs in the pulsatile flow experiments. These results emphasize the need for further studies to fully define the relationship between energy losses and TCPC vessel architecture in non-steady flow physiologic situations.
authors.affiliation: Cardiovascular Flow Dynamics Laboratory, University of Colorado, The Children's Hospital, Denver, Colorado, USA. degroff.curt@tchden.org
authors.forename: Curt G
authors.initials: CG
authors.lastname: DeGroff
authors.forename: Robin
authors.initials: R
authors.lastname: Shandas
mesh_terms: D001783:Blood Flow Velocity; D002319:Cardiovascular System; D018729:Fontan Procedure / Q000379:methods*; D006439:Hemodynamics; D006801:Humans; D008962:Models, Theoretical; D012039:Regional Blood Flow; D013997:Time Factors