title: Bicuspid aortic cusp fusion morphology alters aortic three-dimensional outflow patterns, wall shear stress, and expression of aortopathy.
abstract: BACKGROUND
  Aortic 3-dimensional blood flow was analyzed to investigate altered ascending aorta (AAo) hemodynamics in bicuspid aortic valve (BAV) patients and its association with differences in cusp fusion patterns (right-left, RL versus right-noncoronary, RN) and expression of aortopathy.
  
  
  RESULTS
  Four-dimensional flow MRI measured in vivo 3-dimensional blood flow in the aorta of 75 subjects: BAV patients with aortic dilatation stratified by leaflet fusion pattern (n=15 RL-BAV, mid AAo diameter=39.9±4.4 mm; n=15 RN-BAV, 39.6±7.2 mm); aorta size controls with tricuspid aortic valves (n=30, 41.0±4.4 mm); healthy volunteers (n=15, 24.9±3.0 mm). Aortopathy type (0-3), systolic flow angle, flow displacement, and regional wall shear stress were determined for all subjects. Eccentric outflow jet patterns in BAV patients resulted in elevated regional wall shear stress (P<0.0125) at the right-anterior walls for RL-BAV and right-posterior walls for RN-BAV in comparison with aorta size controls. Dilatation of the aortic root only (type 1) or involving the entire AAo and arch (type 3) was found in the majority of RN-BAV patients (87%) but was mostly absent for RL-BAV patients (87% type 2). Differences in aortopathy type between RL-BAV and RN-BAV patients were associated with altered flow displacement in the proximal and mid AAo for type 1 (42%-81% decrease versus type 2) and distal AAo for type 3 (33%-39% increase versus type 2).
  
  
  CONCLUSIONS
  The presence and type of BAV fusion was associated with changes in regional wall shear stress distribution, systolic flow eccentricity, and expression of BAV aortopathy. Hemodynamic markers suggest a physiological mechanism by which the valve morphology phenotype can influence phenotypes of BAV aortopathy.
authors.affiliation: Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL (R.M., A.J.B., SS., P.E., J. Collins, J. Carr, M.M.); Division of Cardiology, Northwestern University, Chicago, IL (P.K.); Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Canada (P.W.M.F.); Division of Cardiothoracic Surgery, Northwestern University, Chicago, IL (P.W.M.F., S.C.M., P.M.)); and Department Biomedical Engineering, McCormick School of Engineering, Northwestern University, Chicago, IL (M.M.).
authors.forename: Riti
authors.initials: R
authors.lastname: Mahadevia
authors.forename: Alex J
authors.initials: AJ
authors.lastname: Barker
authors.forename: Susanne
authors.initials: S
authors.lastname: Schnell
authors.forename: Pegah
authors.initials: P
authors.lastname: Entezari
authors.forename: Preeti
authors.initials: P
authors.lastname: Kansal
authors.forename: Paul W M
authors.initials: PW
authors.lastname: Fedak
authors.forename: S Chris
authors.initials: SC
authors.lastname: Malaisrie
authors.forename: Patrick
authors.initials: P
authors.lastname: McCarthy
authors.forename: Jeremy
authors.initials: J
authors.lastname: Collins
authors.forename: James
authors.initials: J
authors.lastname: Carr
authors.forename: Michael
authors.initials: M
authors.lastname: Markl
mesh_terms: D000328:Adult; D000368:Aged; D001011:Aorta / Q000473:pathology* / Q000503:physiopathology*; D001018:Aortic Diseases / Q000453:epidemiology / Q000473:pathology* / Q000503:physiopathology*; D001021:Aortic Valve / Q000473:pathology / Q000503:physiopathology; D000082882:Bicuspid Aortic Valve Disease; D001783:Blood Flow Velocity; D005260:Female; D006330:Heart Defects, Congenital / Q000453:epidemiology / Q000473:pathology* / Q000503:physiopathology*; D006349:Heart Valve Diseases / Q000453:epidemiology / Q000473:pathology* / Q000503:physiopathology*; D006439:Hemodynamics; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D013314:Stress, Mechanical; D055815:Young Adult
keywords: aortic diseases; bicuspid aortic valve; hemodynamics; magnetic resonance imaging