title: Greater asymmetric wall shear stress in Sievers' type 1/LR compared with 0/LAT bicuspid aortic valves after valve-sparing aortic root replacement.
abstract: OBJECTIVE
  To evaluate the role of commissure orientation on downstream blood flow patterns and ascending aortic wall shear stress (WSS) in patients with bicuspid aortic valves (BAV) after valve-sparing aortic root replacement (V-SARR).
  
  
  METHODS
  Nineteen BAV patients after V-SARR (9 Sievers' type 1/LR [type 1 valve with fusion of the left and right cusps] and 10 Sievers' type 0/LAT ["naturally perfect"; type 0 valve without the presence of a raphe, and with the 2 commissures oriented right-anterior-to-left-posterior]) were imaged using time-resolved 3-D phase contrast magnetic resonance imaging. A control group of 5 unoperated tricuspid aortic valve patients were used for comparison purposes. Wall shear stress and eccentricity of flow normalized to aortic diameter were measured in planes placed perpendicular to the axis of the ascending aorta at the level of the sinotubular junction (proximal ascending), main pulmonary artery (mid-ascending), and origin of the brachiocephalic (distal ascending).
  
  
  RESULTS
  The ratio of WSS along the outer curvature to that along the inner curvature was greater in Sievers' type 1/LR patients compared with Sievers' type 0/LAT patients in the proximal (3.8 ± 1.6 vs 2.1 ± 0.9, P = .009) and mid- ascending aorta (4.5 ± 2.4 vs 2.4 ± 1.3, P = .027). Relative to control normal tricuspid patients, Sievers' type 1/LR BAV patients had a higher WSS ratio in the mid-ascending aorta (4.5 ± 2.4 vs 1.2 ± 1.2, P = .007). Conversely, WSS in Sievers' type 0/LAT patients was not different than in normal tricuspid patients.
  
  
  CONCLUSIONS
  After V-SARR, BAV cusp morphology has a major impact on the pattern of blood flow and WSS in the ascending aorta.
authors.affiliation: Division of Cardiac, Thoracic, and Vascular Surgery, New York Presbyterian Hospital, Columbia University Medical Center, New York, NY.
authors.forename: Elizabeth H
authors.initials: EH
authors.lastname: Stephens
authors.affiliation: Department of Radiology, Stanford University School of Medicine, Stanford, Calif.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Hope
authors.affiliation: Department of Cardiovascular Surgery, Heart Center, University of Freiburg, Freiburg, Germany.
authors.forename: Fabian A
authors.initials: FA
authors.lastname: Kari
authors.affiliation: Department of Cardiothoracic Surgery, Linköping University Hospital, Linköping, Sweden.
authors.forename: John-Peder Escobar
authors.initials: JP
authors.lastname: Kvitting
authors.affiliation: Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, Calif.
authors.forename: David H
authors.initials: DH
authors.lastname: Liang
authors.affiliation: Department of Radiology, Stanford University School of Medicine, Stanford, Calif.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Herfkens
authors.affiliation: Department of Cardiovascular and Thoracic Surgery, Stanford University School of Medicine, Stanford, Calif. Electronic address: dcm@stanford.edu.
authors.forename: D Craig
authors.initials: DC
authors.lastname: Miller
mesh_terms: D000328:Adult; D001021:Aortic Valve / Q000002:abnormalities* / Q000503:physiopathology / Q000601:surgery; D000082882:Bicuspid Aortic Valve Disease; D005260:Female; D006349:Heart Valve Diseases / Q000503:physiopathology* / Q000601:surgery*; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D012039:Regional Blood Flow; D013314:Stress, Mechanical; D055815:Young Adult
keywords: 4D flow MRI; Bicuspid aortic valve; thoracic aorta; valve-sparing aortic root replacement