title: Early biomechanical changes in lower extremity vein grafts--distinct temporal phases of remodeling and wall stiffness.
abstract: BACKGROUND
  The geometric and biomechanical changes that contribute to vein graft remodeling are not well established. We sought to measure patterns of adaptation in lower extremity vein grafts and assess their correlation with clinical outcomes.
  
  
  METHODS
  We conducted a prospective, longitudinal study of patients undergoing infrainguinal reconstruction with autogenous conduit. In addition to standard duplex surveillance, lumen diameter (of a defined index segment of the conduit) and pulse wave velocity (PWV) were assessed by ultrasound imaging at surgery and at 1, 3, and 6 months postoperatively. Graft dimensions and wall stiffness were correlated with clinical outcomes.
  
  
  RESULTS
  There were 92 patients and 96 limbs in this study. On average, vein graft lumen diameter increased during the first month of implantation from 0.37 +/- .01 cm to 0.45 +/- 0.02 cm (mean +/- SEM; P = .002), representing a relative change of +21.6% (median +/- 14%; range, -31 to +67%) during this period. Of the entire cohort, 72% of grafts demonstrated appreciable dilation of the index segment during the first month. Index segment lumen diameter did not change appreciably beyond 1 month, with the notable exception of arm vein conduits, which showed continued tendency to dilate. PWV increased during the first 6 months (17.2 +/- 1.2 m/s to 23.2 +/- 2.4 m/s; P = .008), reflecting a nearly 40% increase in conduit stiffness (2.0 +/- .6 Mdynes/cm to 3.3 +/- .8 Mdynes/cm, P = .01). The greatest relative increase (25%) in PWV occurred from months 1 to 3. Loss of primary patency occurred in 24 cases (19 revisions, 5 occlusions), with a mean reintervention time of 7.6 months. Grafts that demonstrated early positive remodeling (lumen dilatation) had a trend of increased primary patency (P = .08, log rank). Among the grafts that failed, a trend was noted toward greater wall stiffness at 1 month, 2.7 vs 1.5 Mdynes (P = .08).
  
  
  CONCLUSIONS
  Vein graft remodeling appears to involve at least two distinct temporal phases. Outward remodeling of the lumen occurs early, and wall stiffness changes occur in a more delayed fashion. Early outward remodeling may be important for successful vein graft adaptation.
authors.affiliation: Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Owens
authors.forename: Nicole
authors.initials: N
authors.lastname: Wake
authors.forename: Jeffrey G
authors.initials: JG
authors.lastname: Jacot
authors.forename: Marie
authors.initials: M
authors.lastname: Gerhard-Herman
authors.forename: Peter
authors.initials: P
authors.lastname: Gaccione
authors.forename: Michael
authors.initials: M
authors.lastname: Belkin
authors.forename: Mark A
authors.initials: MA
authors.lastname: Creager
authors.forename: Michael S
authors.initials: MS
authors.lastname: Conte
mesh_terms: D000368:Aged; D000792:Angiography; D001157:Arterial Occlusive Diseases / Q000175:diagnosis / Q000601:surgery*; D001783:Blood Flow Velocity / Q000502:physiology; D004548:Elasticity; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011150:Popliteal Artery; D011446:Prospective Studies; D012501:Saphenous Vein / Q000000981:diagnostic imaging / Q000502:physiology* / Q000637:transplantation*; D016896:Treatment Outcome; D018616:Ultrasonography, Doppler, Duplex; D014654:Vascular Patency / Q000502:physiology*