title: Computational fluid dynamics in patients with continuous-flow left ventricular assist device support show hemodynamic alterations in the ascending aorta.
abstract: OBJECTIVE
  Increased use of continuous-flow left ventricular assist devices for long-term mechanical support necessitates a better understanding of hemodynamic changes in the native heart and the ascending aorta. By using patient-specific computational models, correlations of potentially adverse hemodynamic conditions with the orientation of the left ventricular assist device outflow graft and their relationship with aortic insufficiency and ischemic events were investigated.
  
  
  METHODS
  Computed hemodynamic parameters, including wall shear stress, pressure in the ascending aorta, and dissipation of turbulent energy, were correlated with the orientation of the left ventricular assist device graft outflow in 5 patients (4 with the HeartMate II device [Thoratec Corp, Pleasanton, Calif] and 1 with the HeartWare Ventricular Assist Device [HeartWare Inc, Framingham, Mass]; 3 patients experienced moderate aortic insufficiency, and 2 patients experienced ischemic events). Hemodynamic conditions for aortic insufficiency and ischemic events were differentiated by linear discriminant analysis.
  
  
  RESULTS
  Positive correlations between left ventricular assist device outflow graft orientation and wall shear stress, pressure, and turbulent energy dissipation in the ascending aorta were found (R(2) > 0.68). Linear discriminant analysis indicated a relationship of the velocity magnitude of retrograde flow toward the aortic root with aortic insufficiency and of the turbulent energy and wall shear stress with ischemic events.
  
  
  CONCLUSIONS
  Computational fluid dynamic simulations using clinical image data indicate altered hemodynamic conditions after left ventricular assist device implantation. Consequently, the left ventricular assist device outflow graft should be placed so the jet of blood is aimed toward the lumen of the aortic arch to avoid turbulences that will increase wall shear stress and retrograde pressure of the aortic root. Further investigations are warranted to confirm these findings in a larger patient cohort.
authors.affiliation: Methodist DeBakey Heart & Vascular Center, Houston Methodist Hospital, Houston, Tex. Electronic address: CKarmonik@tmhs.org.
authors.forename: Christof
authors.initials: C
authors.lastname: Karmonik
authors.affiliation: Methodist DeBakey Heart & Vascular Center, Houston Methodist Hospital, Houston, Tex; Department of Radiology University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, Ohio.
authors.forename: Sasan
authors.initials: S
authors.lastname: Partovi
authors.affiliation: Methodist DeBakey Heart & Vascular Center, Houston Methodist Hospital, Houston, Tex.
authors.forename: Matthias
authors.initials: M
authors.lastname: Loebe
authors.affiliation: Department of Cardiac Surgery, University Hospital of Heidelberg, Heidelberg, Germany.
authors.forename: Bastian
authors.initials: B
authors.lastname: Schmack
authors.affiliation: Department of Cardiac Surgery, University Hospital of Heidelberg, Heidelberg, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Weymann
authors.affiliation: Methodist DeBakey Heart & Vascular Center, Houston Methodist Hospital, Houston, Tex.
authors.forename: Alan B
authors.initials: AB
authors.lastname: Lumsden
authors.affiliation: Department of Cardiac Surgery, University Hospital of Heidelberg, Heidelberg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Karck
authors.affiliation: Department of Cardiac Surgery, University Hospital of Heidelberg, Heidelberg, Germany.
authors.forename: Arjang
authors.initials: A
authors.lastname: Ruhparwar
mesh_terms: D001011:Aorta / Q000503:physiopathology*; D001022:Aortic Valve Insufficiency / Q000503:physiopathology*; D003198:Computer Simulation; D006353:Heart-Assist Devices; D006439:Hemodynamics; D006801:Humans; D057446:Hydrodynamics; D008955:Models, Cardiovascular; D012189:Retrospective Studies