title: Bidirectional superior cavopulmonary anastomosis improves mechanical efficiency in dilated atriopulmonary connections.
abstract: OBJECTIVE
  Few therapeutic options exist for patients with failing dilated atriopulmonary connections. We addressed the hypothesis that a bidirectional superior cavopulmonary anastomosis will improve the hemodynamic efficiency of dilated atriopulmonary connections while maintaining physiologic pulmonary flow distributions.
  
  
  METHODS
  Dilated atriopulmonary connections with and without a bidirectional superior cavopulmonary anastomosis were created in explanted sheep heart preparations and transparent glass models. A mechanical energy balance and flow visualization were performed for 6 flow rates (1-6 L/min), both with and without the bidirectional superior cavopulmonary anastomosis, and were then compared. A novel contrast echocardiographic technique was used to quantify inferior vena cava flow (hepatic venous return) distributions into the pulmonary arteries.
  
  
  RESULTS
  The rate of fluid-energy dissipation was 52% +/- 14% greater in the dilated atriopulmonary anastomosis than in the bidirectional superior cavopulmonary anastomosis model over the range of flow rates studied (P = 6.3E(-3)). Total venous return passing to the right pulmonary artery increased from 41% +/- 2% to 47% +/- 3% (P = 9.7E(-3)) and that for inferior vena cava flow decreased from and 42% +/- 3% to 12% +/- 4% (P = 3.3E(-4)) after addition of the bidirectional superior cavopulmonary anastomosis. Flow visualization confirmed more ordered atrial flow in the bidirectional cavopulmonary anastomosis model, resulting from a reduction of caval flow stream collision and interaction.
  
  
  CONCLUSIONS
  A bidirectional cavopulmonary anastomosis reduces fluid-energy dissipation in atriopulmonary connections, provides a physiologic distribution of total flow, and maintains some hepatic venous flow to each lung. This approach may be a technically simple alternative to atriopulmonary takedown procedures and conversions to total cavopulmonary connections in selected patients.
authors.affiliation: Cardiac Dynamics Laboratory, Division of Cardiology, Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA. alardo@mri.jhu.edu
authors.forename: A C
authors.initials: AC
authors.lastname: Lardo
authors.forename: S A
authors.initials: SA
authors.lastname: Webber
authors.forename: A
authors.initials: A
authors.lastname: Iyengar
authors.forename: P J
authors.initials: PJ
authors.lastname: del Nido
authors.forename: I
authors.initials: I
authors.lastname: Friehs
authors.forename: E G
authors.initials: EG
authors.lastname: Cape
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D004108:Dilatation, Pathologic / Q000209:etiology; D004452:Echocardiography; D006321:Heart / Q000502:physiology*; D006325:Heart Atria / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery; D018610:Heart Bypass, Right / Q000009:adverse effects / Q000379:methods*; D006439:Hemodynamics / Q000502:physiology; D018056:Hemorheology; D006503:Hepatic Veins / Q000000981:diagnostic imaging; D007834:Lasers; D008953:Models, Anatomic; D011651:Pulmonary Artery / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery; D011652:Pulmonary Circulation / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D012756:Sheep; D014682:Vena Cava, Inferior / Q000000981:diagnostic imaging