title: Growth and remodeling of canine common iliac vein in response to venous reflux and hypertension.
abstract: OBJECTIVE
  The passive properties of the venous wall are important for the compliance function of the venous system. The objective of this study was to quantify the passive biomechanical response and structural growth and remodeling of veins subjected to chronic venous reflux and hypertension.
  
  
  METHODS
  To investigate the effects of venous reflux on venous mechanics, the tricuspid valve was injured in a canine model by disrupting the chordae tendineae. The conventional inflation-extension protocol in conjunction with intravascular ultrasound was used to investigate the passive biomechanical response of both control common iliac veins (n = 9 dogs) and common iliac veins subjected to 8 weeks of venous reflux and hypertension (n = 9 dogs). The changes in vein wall thickness and constituent composition were quantified by multiphoton microscopy and histologic evaluation.
  
  
  RESULTS
  Biomechanical results indicate that the veins became less compliant when exposed to 8 weeks of chronic venous reflux and hypertension. The mechanical stiffening was found to be associated with a significant increase in wall thickness (P < .05) and collagen-to-elastin ratio (P < .05). After 8 weeks of chronic reflux and hypertension, the circumferential vein wall stress was significantly reduced (P < .05) because of wall thickening, although it was not restored to control levels.
  
  
  CONCLUSIONS
  The growth and remodeling of the venous wall reduces the wall stress, but the stress remains higher than at baseline at 8 weeks. The compliance of the veins also decreases because of the increase in wall thickness and remodeling of the microstructure of the venous wall. These findings provide insight into potential adaptations of the venous system in reflux and hypertension.
authors.affiliation: Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, Ind.
authors.forename: Margaret
authors.initials: M
authors.lastname: Brass
authors.affiliation: Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, Ind; Research and Development, 3DT Holdings, LLC, Indianapolis, Ind.
authors.forename: Zachary C
authors.initials: ZC
authors.lastname: Berwick
authors.affiliation: Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, Ind.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, Ind.
authors.forename: Huan
authors.initials: H
authors.lastname: Chen
authors.affiliation: Research Engineering, Cook Medical, Bloomington, Ind.
authors.forename: Joshua
authors.initials: J
authors.lastname: Krieger
authors.affiliation: Research Engineering, Cook Medical, Bloomington, Ind.
authors.forename: Sean
authors.initials: S
authors.lastname: Chambers
authors.affiliation: Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, Ind; Department of Surgery, Indiana University-Purdue University Indianapolis, Indianapolis, Ind; Department of Cellular and Integrative Physiology, Indiana University-Purdue University Indianapolis, Indianapolis, Ind. Electronic address: gkassab@calmi2.org.
authors.forename: Ghassan S
authors.initials: GS
authors.lastname: Kassab
mesh_terms: D000818:Animals; D003094:Collagen; D003187:Compliance; D004195:Disease Models, Animal; D004285:Dogs; D004549:Elastin; D005268:Femoral Vein; D006973:Hypertension; D007084:Iliac Vein / Q000473:pathology*; D013314:Stress, Mechanical; D014689:Venous Insufficiency
chemical_list: D003094:Collagen; D004549:Elastin