title: Computational analysis of hybrid Norwood circulation with distal aortic arch obstruction and reverse Blalock-Taussig shunt.
abstract: BACKGROUND
  The hemodynamics characteristics of the hybrid Norwood (HN) procedure differ from those of the conventional Norwood and are not fully understood. We present a multiscale model of HN circulation to understand local hemodynamics and effects of aortic arch stenosis and a reverse Blalock-Taussig shunt (RBTS) on coronary and carotid perfusion.
  
  
  METHODS
  Four 3-dimensional models of four HN anatomic variants were developed, with and without 90% distal preductal arch stenosis and with and without a 4-mm RBTS. A lumped parameter model of the circulation was coupled to a local 3-dimensional computational fluid dynamics model. Outputs from the lumped parameter model provided waveform boundary conditions for the computational fluid dynamics model.
  
  
  RESULTS
  A 90% distal arch stenosis reduced pressure and net flow-rate through the coronary and carotid arteries by 30%. Addition of the RBTS completely restored pressure and flow rate to baseline in these vessels. Zones of flow stagnation, flow reversal, and recirculation in the presence of stenosis were rendered more orderly by addition of the RBTS. In the absence of stenosis, presence of the shunt resulted in extensive zones of disturbed flow within the RBTS and arch.
  
  
  CONCLUSIONS
  We found that a 4-mm × 21-mm RBTS completely compensated for the effects of a 90% discrete stenosis of the distal aortic arch in the HN. Placed preventatively, the RBTS and arch displayed zones with thrombogenic potential showing recirculation and stagnation that persist for a substantial fraction of the cardiac cycle, indicating that anticoagulation should be considered with a prophylactic RBTS.
authors.affiliation: Department of Mechanical, Materials and Aerospace Engineering, College of Engineering and Computer Science, the University of Central Florida, Orlando, Florida, USA.
authors.forename: Andres
authors.initials: A
authors.lastname: Ceballos
authors.forename: I Ricardo
authors.initials: IR
authors.lastname: Argueta-Morales
authors.forename: Eduardo
authors.initials: E
authors.lastname: Divo
authors.forename: Ruben
authors.initials: R
authors.lastname: Osorio
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Caldarone
authors.forename: Alain J
authors.initials: AJ
authors.lastname: Kassab
authors.forename: William M
authors.initials: WM
authors.lastname: Decampli
mesh_terms: D001013:Aorta, Thoracic / Q000503:physiopathology*; D001024:Aortic Valve Stenosis / Q000503:physiopathology*; D058366:Blalock-Taussig Procedure; D006801:Humans; D021621:Imaging, Three-Dimensional; D008955:Models, Cardiovascular; D058327:Norwood Procedures; D012039:Regional Blood Flow