title: Local mechanical and structural properties of healthy and diseased human ascending aorta tissue.
abstract: OBJECTIVE
  This study investigates the mechanics and histology of healthy and dilated human ascending aortas (AA). The regional variation in mechanical response and tissue structure were compared.
  
  
  METHODS
  Rings of human AA from healthy (n=5), dilated tricuspid aortic valve (TAV, n=5), and dilated bicuspid aortic valve (BAV, n=6) patients were mechanically tested. Each aortic ring was sectioned into quadrants-anterior, posterior, medial (inner curvature) and lateral (outer curvature). Low- and high-stress elastic moduli were calculated from the equibiaxial stress strain curve to determine the local mechanical properties. Histological analysis was used to quantify the percent composition of elastin, collagen, and smooth muscle cells.
  
  
  RESULTS
  BAV tissue was thinnest and contained the largest percent composition of collagen. Both TAV and BAV tissue had significantly less elastin than healthy tissue. At low strain in the circumferential direction, TAV tissue was on average the least stiff. The elastic modulus was dependent on quadrant and tissue type but not direction (isotropic). Generally, the lateral quadrant tissue was the stiffest and the medial quadrant the least stiff. There were no apparent local variations in the tissue histology.
  
  
  CONCLUSIONS
  Local variations in tissue thickness and mechanical properties were evident in all samples analyzed and may be linked to the type of aortic valve present.
authors.affiliation: Department of Chemical Engineering, McGill University, Montreal, Quebec, Canada.
authors.forename: Nusrat
authors.initials: N
authors.lastname: Choudhury
authors.forename: Olivier
authors.initials: O
authors.lastname: Bouchot
authors.forename: Leonie
authors.initials: L
authors.lastname: Rouleau
authors.forename: Dominique
authors.initials: D
authors.lastname: Tremblay
authors.forename: Raymond
authors.initials: R
authors.lastname: Cartier
authors.forename: Jagdish
authors.initials: J
authors.lastname: Butany
authors.forename: Rosaire
authors.initials: R
authors.lastname: Mongrain
authors.forename: Richard L
authors.initials: RL
authors.lastname: Leask
mesh_terms: D000328:Adult; D000368:Aged; D001011:Aorta / Q000473:pathology / Q000503:physiopathology*; D001021:Aortic Valve / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D003094:Collagen / Q000378:metabolism; D004108:Dilatation, Pathologic / Q000473:pathology / Q000503:physiopathology*; D055119:Elastic Modulus; D004548:Elasticity / Q000502:physiology; D004549:Elastin / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D013314:Stress, Mechanical; D014261:Tricuspid Valve / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*
chemical_list: D003094:Collagen; D004549:Elastin