title: Assessment of micro-mechanical variations in experimental arteriovenous fistulae using atomic force microscopy.
abstract: OBJECTIVE
  This study presents a method to quantify micro-stiffness variations in experimental arteriovenous fistulae (AVF).
  
  
  METHODS
  AVF created by anastomosing the superficial epigastric vein to the femoral artery in Sprague-Dawley rats were allowed to remodel for 21 days before being harvested and preserved in culture medium. A custom atomic force microscope was used to measure microvascular stiffness (Young's modulus) in three areas of the AVF: the inflow artery, the juxta-anastomotic area, and the outflow vein. Morphometric measurements and collagen and elastin contents were also determined.
  
  
  RESULTS
  Atomic force microscopy indentation revealed an increased stiffness in the juxta-anastomotic area of the AVF compared to the outflow vein and inflow artery. The juxta-anastomotic area was also significantly stiffer than the contralateral vein. The lack of elasticity (higher Young's modulus) of the juxta-anastomotic region was associated with a thicker vascular wall that was rich in collagen but poor in elastin.
  
  
  CONCLUSIONS
  This study demonstrates for the first time the feasibility of using atomic force microscopy to measure local stiffness variations in experimental AVF. This technique could be instrumental in advancing our understanding of how micro-spatial organization of the AVF wall determines the overall biomechanical performance of this type of vascular access.
authors.affiliation: Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, Florida - USA.
authors.forename: Tyler
authors.initials: T
authors.lastname: Laurito
authors.affiliation: Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, Florida - USA.
authors.forename: Vivian
authors.initials: V
authors.lastname: Sueiras
authors.affiliation: DeWitt Daughtry Family Department of Surgery, University of Miami Miller School of Medicine, Miami, Florida - USA.
authors.forename: Natasha
authors.initials: N
authors.lastname: Fernandez
authors.affiliation: DeWitt Daughtry Family Department of Surgery, University of Miami Miller School of Medicine, Miami, Florida - USA.
authors.forename: Luis A
authors.initials: LA
authors.lastname: Escobar
authors.affiliation: DeWitt Daughtry Family Department of Surgery, University of Miami Miller School of Medicine, Miami, Florida - USA.
authors.forename: Laisel
authors.initials: L
authors.lastname: Martinez
authors.affiliation: Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, Florida - USA.|DeWitt Daughtry Family Department of Surgery, University of Miami Miller School of Medicine, Miami, Florida - USA.
authors.forename: Fotios
authors.initials: F
authors.lastname: Andreopoulos
authors.affiliation: Section of Interventional Nephrology, University of Miami Miller School of Medicine, Miami, Florida - USA.
authors.forename: Loay H
authors.initials: LH
authors.lastname: Salman
authors.affiliation: DeWitt Daughtry Family Department of Surgery, University of Miami Miller School of Medicine, Miami, Florida - USA.
authors.forename: Roberto I
authors.initials: RI
authors.lastname: Vazquez-Padron
authors.affiliation: Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, Florida - USA.
authors.forename: Noël M
authors.initials: NM
authors.lastname: Ziebarth
mesh_terms: D000818:Animals; D001166:Arteriovenous Shunt, Surgical; D001696:Biomechanical Phenomena; D003094:Collagen / Q000378:metabolism; D055119:Elastic Modulus; D004549:Elastin / Q000378:metabolism; D005263:Femoral Artery / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D018625:Microscopy, Atomic Force; D023421:Models, Animal; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow; D013997:Time Factors; D066253:Vascular Remodeling; D059289:Vascular Stiffness; D014680:Veins / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery*
chemical_list: D003094:Collagen; D004549:Elastin