title: Regional mechanical properties of human pulmonary root used for the Ross operation.
abstract: OBJECTIVE
  Significant dilation of the pulmonary autograft after the Ross operation is problematic and requires reoperation. Autograft remodeling occurs in response to the immediate rise in pressure and consequent wall stress. The stress-strain response of the pulmonary root plays an important role in understanding the structural and functional changes of the autograft following the Ross procedure. At present, limited data are available on the mechanical properties of fresh human pulmonary roots; hence, the study aim was to determine the regional mechanical properties of human pulmonary roots.
  
  
  METHODS
  Eighteen fresh healthy specimens of human pulmonary root were obtained from the California Transplant Donor Network (Oakland, CA, USA). Five regions of the pulmonary root--anterior and posterior pulmonary artery (PA), and each of the three sinuses--were subjected to displacement-controlled equibiaxial stretch testing within 24 h of cross-clamp time. Comparisons between the different regions of the pulmonary root were made based on tissue stiffness at physiologic stress. Histologic analyses were also performed of the fibrous structures of the PA and sinuses.
  
  
  RESULTS
  Human PA and sinuses demonstrated a nonlinear response to loading, with no directional dependency to biaxial loading. The anterior PA was significantly more compliant than the posterior PA and the three sinuses in both circumferential and longitudinal directions (p < 0.04). However, there was no significant difference between the stiffness of the posterior PA and that of the three sinuses (p > 0.43), or among the three sinuses (p > 0.30) in the two directions. A tight, more dense weave of elastin was found in the anterior PA than in either the posterior PA or the sinuses.
  
  
  CONCLUSIONS
  Significant inherent differences in compliance were demonstrated among different regions of the human pulmonary root. These regional differences may impact upon pulmonary autograft remodeling following the Ross operation, and also influence late autograft dilation.
authors.affiliation: Department of Surgery, University of California at San Francisco Medical Center (UCSF), San Francisco, CA 94143-0118, USA.
authors.forename: Ali N
authors.initials: AN
authors.lastname: Azadani
authors.forename: Sam
authors.initials: S
authors.lastname: Chitsaz
authors.forename: Peter B
authors.initials: PB
authors.lastname: Matthews
authors.forename: Nicolas
authors.initials: N
authors.lastname: Jaussaud
authors.forename: James
authors.initials: J
authors.lastname: Leung
authors.forename: Liang
authors.initials: L
authors.lastname: Ge
authors.forename: Elaine E
authors.initials: EE
authors.lastname: Tseng
mesh_terms: D000328:Adult; D001021:Aortic Valve / Q000502:physiology*; D001022:Aortic Valve Insufficiency / Q000601:surgery*; D001696:Biomechanical Phenomena / Q000502:physiology; D003094:Collagen / Q000502:physiology; D003187:Compliance / Q000502:physiology; D004549:Elastin / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D008875:Middle Aged; D008955:Models, Cardiovascular; D011651:Pulmonary Artery / Q000033:anatomy & histology / Q000502:physiology* / Q000637:transplantation*; D013314:Stress, Mechanical; D014182:Transplantation, Autologous
chemical_list: D003094:Collagen; D004549:Elastin