title: Ultrasound measurement of brachial artery elasticity prior to hemodialysis access placement: a pilot study.
abstract: OBJECTIVE
  Successful hemodialysis requires reliable vascular access that can deliver adequate blood flow. An arteriovenous fistula is preferred for access because of its longevity and low frequency of complications, but up to 60% of arteriovenous fistulas created surgically are never suitable for hemodialysis because of nonmaturation (insufficient vascular dilatation). Decreased arterial elasticity may impair dilatation, thereby affecting fistula maturation. This study evaluated the feasibility of brachial artery elasticity measurement in patients with chronic kidney disease obtained during routine pre-operative mapping ultrasound (US) imaging before hemodialysis access placement and compared the measurements to those obtained in healthy volunteers.
  
  
  METHODS
  Brachial artery functional US studies were collected from 75 patients undergoing routine preoperative mapping for hemodialysis access and 50 healthy volunteers. Vascular strain was calculated from the change in intima-media thickness between end systole and end diastole, and vascular stress was estimated from the pulse pressure. Assuming a linear elastic medium, the elastic modulus was estimated as the ratio of vascular stress to strain.
  
  
  RESULTS
  Elastic modulus measurements were significantly higher in patients than in volunteers (130 versus 100 kPa; P = .01). With combined volunteer and patient data, there was a significant correlation between elasticity and systolic blood pressure (R2 = 0.23; P < .001). Elasticity was correlated with age in volunteers but not in patients (R2 = 0.14; P = .017; R2 < .001; P = .829, respectively).
  
  
  CONCLUSIONS
  This analysis of clinical arterial vessel biomechanics shows that a noninvasive US measurement can detect elastic modulus differences between patients with chronic kidney disease and healthy individuals. Future studies will correlate the elastic modulus with histologic characteristics and eventual arteriovenous fistula maturation, which may provide supplemental information on arterial biomechanical properties as a useful addition to current predictors of fistula success.
authors.affiliation: MBA, Department of Biomedical Engineering, University of Alabama at Birmingham, G082 Volker Hall, 1670 University Blvd, Birmingham, AL 35294-0019, USA.
authors.forename: Anna G
authors.initials: AG
authors.lastname: Sorace
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Robbin
authors.forename: Heidi
authors.initials: H
authors.lastname: Umphrey
authors.forename: Carl A
authors.initials: CA
authors.lastname: Abts
authors.forename: Joel L
authors.initials: JL
authors.lastname: Berry
authors.forename: Mark E
authors.initials: ME
authors.lastname: Lockhart
authors.forename: Michael
authors.initials: M
authors.lastname: Allon
authors.forename: Kenneth
authors.initials: K
authors.lastname: Hoyt
mesh_terms: D000328:Adult; D000368:Aged; D000714:Anastomosis, Surgical / Q000379:methods*; D001916:Brachial Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D006435:Renal Dialysis / Q000379:methods*; D051436:Renal Insufficiency, Chronic / Q000000981:diagnostic imaging* / Q000503:physiopathology* / Q000534:rehabilitation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018084:Ultrasonography, Interventional / Q000379:methods