title: Long-term arterial adaptation to high blood flow in the feeding artery of vascular access for hemodialysis.
abstract: OBJECTIVE
  Arteries continuously respond to changing tissue demands and to hemodynamic conditions by altering their diameter and wall structure. The relatively slow dilatation of the feeding artery of vascular accesses continues at least two years after access creation with a continuous decrease in wall shear rate (WSR), which however, remains highly supra-physiological. The aim of this study was to test the hypothesis that after a longer time period the WSR returns to its baseline value.
  
  
  METHODS
  In a cross-sectional study patients with arteriovenous fistulae were classified into four  groups according to the access vintage (from new access to accesses older than six years). The WSR, cross-sectional area, and mean circumferential wall stress were measured and compared between groups.
  
  
  RESULTS
  WSR decreased from group 1 (fistula < ninety days old) to group 4 (fistulae > six years old) with a concomitant increase in internal diameter. Patients with the oldest access had normal WSR values (compared to the contralateral brachial artery) and the largest internal diameter of the feeding artery. In diabetic patients the absolute values of WSR were higher and internal diameter was lower compared to nondiabetic patients.
  
  
  CONCLUSIONS
  Brachial artery WSR is normal in accesses older than six years with an increased internal diameter and wall cross-sectional area as compared to "younger" accesses. This suggests a process of vascular remodeling with an increase in vascular wall mass and normalization of WSR to physiologic values at the price of increased mean cross-sectional wall stress.
authors.affiliation: Third Department of Internal Medicine,General University Hospital and First Faculty of Medicine, Charles University, Prague, Czech Republic. Vladimir.Tuka@vfn.cz
authors.forename: Vladimir
authors.initials: V
authors.lastname: Tuka
authors.forename: Jan
authors.initials: J
authors.lastname: Malik
authors.forename: Eva
authors.initials: E
authors.lastname: Chytilova
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Kudlicka
authors.forename: Marcela
authors.initials: M
authors.lastname: Slavikova
authors.forename: Edwin
authors.initials: E
authors.lastname: Wijnen
authors.forename: Jan H M
authors.initials: JH
authors.lastname: Tordoir
authors.forename: Simon
authors.initials: S
authors.lastname: Van Hooland
mesh_terms: D000222:Adaptation, Physiological; D000368:Aged; D000369:Aged, 80 and over; D001166:Arteriovenous Shunt, Surgical; D001783:Blood Flow Velocity; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D005060:Europe; D005260:Female; D006439:Hemodynamics; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012039:Regional Blood Flow; D006435:Renal Dialysis; D013314:Stress, Mechanical; D013997:Time Factors; D014463:Ultrasonography; D034941:Upper Extremity / Q000098:blood supply*