title: Mechanical characteristics of lyophilized human saphenous vein valves.
abstract: OBJECTIVE
  We investigated the mechanical characteristics of lyophilized human saphenous vein valves to determine their suitability for use as allogeneic transplants to treat chronic venous insufficiency.
  
  
  METHODS
  Fresh cadaveric veins were lyophilized in vacuum bottles within 24 hours of harvest and were stored at room temperature. The veins were reconstituted in saline solution and then were placed in an in vitro flow circuit for evaluation. At varied flow rates, pressures proximal and distal to valves during prograde and retrograde flow were measured. Valve closure times were determined with Doppler examination and spectral analysis. The valves were also stressed to 350 mm Hg on a separate apparatus.
  
  
  RESULTS
  All pressures proximal and distal to the valves remained less than 10 mm Hg during prograde flow. A pressure gradient developed immediately on the reversal of flow. Pressure as high as 200 mm Hg applied against the closed valves was not transmitted beyond the valve. Valve closure times had a mean of 0.31 +/- 0.03 seconds and 0.21 +/- 0.01 seconds for the Doppler examination and spectral analysis, respectively. All valves withstood stress pressures to 350 mm Hg.
  
  
  CONCLUSIONS
  The in vitro mechanical characteristics of the valves of lyophilized veins are similar to known values for normal in vivo valves.
authors.affiliation: Department of Surgery, University of Tennessee Medical Center, Knoxville 37920, USA.
authors.forename: T R
authors.initials: TR
authors.lastname: Reeves
authors.forename: J L
authors.initials: JL
authors.lastname: Cezeaux
authors.forename: J E
authors.initials: JE
authors.lastname: Sackman
authors.forename: D C
authors.initials: DC
authors.lastname: Cassada
authors.forename: M B
authors.initials: MB
authors.lastname: Freeman
authors.forename: S L
authors.initials: SL
authors.lastname: Stevens
authors.forename: M H
authors.initials: MH
authors.lastname: Goldman
mesh_terms: D005612:Freeze Drying; D018056:Hemorheology; D006801:Humans; D066298:In Vitro Techniques; D011312:Pressure; D012501:Saphenous Vein / Q000000981:diagnostic imaging / Q000502:physiology* / Q000637:transplantation; D018608:Ultrasonography, Doppler