title: Valvular function of peripheral veins after hyperemic dilation.
abstract: OBJECTIVE
  We wanted to answer the question of whether physiological dilation of normal extremity veins can induce temporary valvular leakage and reflux.
  
  
  METHODS
  Directional flow was recorded in 22 forearm and popliteal veins by Doppler duplex scanning after distal compression. Reflux was assessed by valve closure time and calculation of a "reflux index," the ratio of backward to forward flow areas.
  
  
  RESULTS
  Hyperemia and enhanced flow did not increase but lowered reflux. During control conditions the mean reflux ratio (backward/forward flow area) of 21 veins was 0.058 and decrease to 0.028 (p < 0.05). Reflux was slightly longer in patients in the erect position in the popliteal vein, compared to forearm veins (with the patients in the sitting position). Significantly increased reflux occurred during hyperemia in only one deep forearm vein (valve closure time 0.92 seconds).
  
  
  CONCLUSIONS
  Most veins of the upper (forearm) and lower extremity (popliteal vein) were competent even after a maneuver that induced venodilation and an increase in blood flow (exercise hyperemia or postocclusion reactive hyperemia). Veins with an inherent valvular weakness can be identified by a hyperemia test with duplex flow analysis.
authors.affiliation: Department of Clinical Physiology, University Hospital, Linköping.
authors.forename: J
authors.initials: J
authors.lastname: Andersson
authors.forename: A
authors.initials: A
authors.lastname: Thurin
authors.forename: O
authors.initials: O
authors.lastname: Thulesius
mesh_terms: D000293:Adolescent; D000328:Adult; D001783:Blood Flow Velocity; D005542:Forearm / Q000098:blood supply*; D006801:Humans; D006940:Hyperemia / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011152:Popliteal Vein / Q000000981:diagnostic imaging / Q000503:physiopathology*; D011187:Posture; D012039:Regional Blood Flow; D013997:Time Factors; D018616:Ultrasonography, Doppler, Duplex; D014664:Vasodilation; D014680:Veins / Q000000981:diagnostic imaging / Q000503:physiopathology; D014689:Venous Insufficiency / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology