title: Energy loss and coronary flow simulation following hybrid stage I palliation: a hypoplastic left heart computational fluid dynamic model.
abstract: OBJECTIVE
  The theoretical differences in energy losses as well as coronary flow with different band sizes for branch pulmonary arteries (PA) in hypoplastic left heart syndrome (HLHS) remain unknown. Our objective was to develop a computational fluid dynamic model (CFD) to determine the energy losses and pulmonary-to-systemic flow rates. This study was done for three different PA band sizes.
  
  
  METHODS
  Three-dimensional computer models of the hybrid procedure were constructed using the standard commercial CFD softwares Fluent and Gambit. The computer models were controlled for bilateral PA reduction to 25% (restrictive), 50% (intermediate) and 75% (loose) of the native branch pulmonary artery diameter. Velocity and pressure data were calculated throughout the heart geometry using the finite volume numerical method. Coronary flow was measured simultaneously with each model. Wall shear stress and the ratio of pulmonary-to-systemic volume flow rates were calculated. Computer simulations were compared at fixed points utilizing echocardiographic and catheter-based metric dimensions.
  
  
  RESULTS
  Restricting the PA band to a 25% diameter demonstrated the greatest energy loss. The 25% banding model produced an energy loss of 16.76% systolic and 24.91% diastolic vs loose banding at 7.36% systolic and 17.90% diastolic. Also, restrictive PA bands had greater coronary flow compared with loose PA bands (50.2 vs 41.9 ml/min). Shear stress ranged from 3.75 Pascals with restrictive PA banding to 2.84 Pascals with loose banding. Intermediate PA banding at 50% diameter achieved a Qp/Qs (closest to 1) at 1.46 systolic and 0.66 diastolic compared with loose or restrictive banding without excess energy loss.
  
  
  CONCLUSIONS
  CFD provides a unique platform to simulate pressure, shear stress as well as energy losses of the hybrid procedure. PA banding at 50% provided a balanced pulmonary and systemic circulation with adequate coronary flow but without extra energy losses incurred.
authors: School of Aerospace Systems, University of Cincinnati, Cincinnati, OH, USA. jeffrey.shuhaiber@gmail.com
authors: Jeffrey H
authors: JH
authors: Shuhaiber
authors: Justin
authors: J
authors: Niehaus
authors: William
authors: W
authors: Gottliebson
authors: Shaaban
authors: S
authors: Abdallah
mesh_terms: D001783:Blood Flow Velocity; D006348:Cardiac Surgical Procedures; D003198:Computer Simulation; D003326:Coronary Circulation; D004734:Energy Metabolism; D020342:Finite Element Analysis; D006439:Hemodynamics; D006801:Humans; D018636:Hypoplastic Left Heart Syndrome / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery*; D021621:Imaging, Three-Dimensional; D008955:Models, Cardiovascular; D009716:Numerical Analysis, Computer-Assisted; D010166:Palliative Care; D011651:Pulmonary Artery / Q000503:physiopathology / Q000601:surgery*; D011652:Pulmonary Circulation; D013314:Stress, Mechanical; D016896:Treatment Outcome
keywords: Computational fluid dynamics; Haemodynamics; Hypoplastic left heart syndrome; Navier–Stokes equations; Simulations
references: Semin Thorac Cardiovasc Surg. 2007 Fall;19(3):238-44
references: 17983951
references: Ann Thorac Surg. 2008 Jun;85(6):2063-70; discussion 2070-1
references: 18498821
references: Interact Cardiovasc Thorac Surg. 2005 Aug;4(4):352-5
references: 17670429
references: J Anat. 1987 Apr;151:107-15
references: 3654345
references: J Thorac Cardiovasc Surg. 1988 Nov;96(5):682-95
references: 3184963
references: Ann Thorac Surg. 2002 Sep;74(3):805-10; discussion 810
references: 12238843
references: N Engl J Med. 2010 May 27;362(21):1980-92
references: 20505177
references: J Thorac Cardiovasc Surg. 2008 Aug;136(2):312-320.e2
references: 18692636
references: Pediatrics. 1985 Nov;76(5):829-33
references: 2932675
references: J Thorac Cardiovasc Surg. 1981 Oct;82(4):511-9
references: 6168869
references: J Thorac Cardiovasc Surg. 2007 Jun;133(6):1653-4
references: 17532977
references: Acta Paediatr Scand. 1986 Jul;75(4):563-8
references: 3751552
references: Ann Thorac Surg. 2009 Sep;88(3):830-7; discussion 837-8
references: 19699907