title: Spectral and profile analysis of Doppler recording following below-knee arterial distal bypasses.
abstract: BACKGROUND
  Arterial below knee distal bypasses are associated with a high risk of thrombosis as compared to proximal bypasses. We assumed that before the bypass occludes, in the early postsurgical period, measurable velocity changes, and/or the presence of high intensity transient signals (HITS) would occur.
  
  
  METHODS
  
  
  
  METHODS
  institutional reference center, hospitalized patients.
  
  
  METHODS
  satisfactory Doppler recording was obtained in 51 among 61 consecutive patients (32 males, 19 females, height: 165+/-7 cm, weight: 68+/-12 kg) suffering lower extremity arterial disease, that underwent saphenous (n=33), prosthetic (n=4) or sequential (n=14) below knee bypasses. We performed a spectral and profile analysis of a single postsurgical 2 hour Doppler recording at the ankle level and analyzed Doppler derived indices and clinical risk factors in the evaluation of the risk of bypass occlusion within 7 days following surgery.
  
  
  RESULTS
  Primary patency at day 7 was observed in 41 of the 51 operated patients. The presence of HITS was found in approximately 30% of the patients and provided no information on the risk of thrombosis. No clinical variable was significantly associated with an increased risk of thrombosis. Whatever the duration of recording, the presence of a diastolic forward flow and wide systolic velocity changes were poor indicators of bypass thrombosis risk. On 512 beat recordings, a mean systolic velocity below 1630 Hz and a standard deviation of the resistance index >0.095 were associated with a 6.74 [1.6-28.4] (p<0.01) and 14.5 [3.6-58.9] (p<0.001) times increases in the risk of bypass occlusion respectively, compared with subjects that do not fulfill each criteria.
  
  
  CONCLUSIONS
  Periods of transient asymptomatic no-flow-reflow events may be observed before the bypass irreversibly occludes. Prolonged Doppler recording should be preferred to short term analyses, to allow for the detection of these transient events and may provide potential indices for future research.
authors.affiliation: Department of Vascular Investigations, CHU, Angers, France.
authors.forename: P
authors.initials: P
authors.lastname: Abraham
authors.forename: M
authors.initials: M
authors.lastname: Eudo
authors.forename: J
authors.initials: J
authors.lastname: Picquet
authors.forename: J L
authors.initials: JL
authors.lastname: Saumet
authors.forename: B
authors.initials: B
authors.lastname: Vielle
authors.forename: B
authors.initials: B
authors.lastname: Enon
mesh_terms: D000465:Algorithms; D001157:Arterial Occlusive Diseases / Q000601:surgery*; D001783:Blood Flow Velocity; D001807:Blood Vessel Prosthesis / Q000009:adverse effects; D016009:Chi-Square Distribution; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007866:Leg / Q000098:blood supply*; D008297:Male; D011446:Prospective Studies; D012372:ROC Curve; D012306:Risk; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013927:Thrombosis / Q000209:etiology; D013997:Time Factors; D018615:Ultrasonography, Doppler, Color; D014654:Vascular Patency