title: Carotid artery stent type influences duplex ultrasonography derived peak systolic velocity: findings of an in-vitro model.
abstract: OBJECTIVE
  The goal of this study is to evaluate the effect of stenting on Doppler ultrasonography (DU) [velocity] signals in an in-vitro carotid model.
  
  
  BACKGROUND
  Considerable debate exists about whether DU overestimates velocity signals and thus the degree of stenosis in previously stented carotid arteries.
  
  
  METHODS
  Constant, pulsatile flow was simulated with an experimental circulatory system containing a nonstenotic ovine internal carotid artery segment. Peak systolic velocity (PSV) and peak diastolic velocity were measured with an intravascular flow wire (FW) and DU. Velocities were evaluated at five predetermined locations within the vessel immediately prior to and following stent placement.
  
  
  RESULTS
  Eleven stents were implanted. DU-derived PSV increased significantly following placement of the X-Act stent (80+/-26 cm/sec [pre] vs. 102+/-29 cm/sec [post], P=0.02), while FW-derived PSV (65+/-23 cm/sec [pre] vs. 66+/-9 cm/sec [post], P=0.93) did not change. The Precise stent did not influence PSV with either method (DU: 76+/-28 cm/sec [pre] vs. 72+/-35 cm/sec [post], P=0.95;), while the Acculink stent showed a trend towards a reduction in DU (69+/-37 cm/sec [pre] vs. 51+/-10 cm/sec [post], P=0.075) and FW (50+/-27 cm/sec [pre] vs. 40+/-12 cm/sec [post], P=0.14) derived PSV. Peak diastolic velocity revealed similar trends as PSV signals depending on the type of stent used.
  
  
  CONCLUSIONS
  Stent type may have significant impact on DU derived velocity signals. DU seems to overestimate PSV in carotid arteries treated with the X-Act stent, but not with the Precise or Acculink stent. Larger scale clinical comparison of various stent types and their impact on DU are needed in order to clarify the value of DU surveillance following carotid artery stenting.
authors.affiliation: Section of Cardiology, Rush University Medical Center, Chicago, Illinois 60612, USA. christian_spies@rush.edu
authors.forename: Christian
authors.initials: C
authors.lastname: Spies
authors.forename: Ripple
authors.initials: R
authors.lastname: Doshi
authors.forename: Jocelyn
authors.initials: J
authors.lastname: Spoon
authors.forename: R Jeffrey
authors.initials: RJ
authors.lastname: Snell
mesh_terms: D000800:Angioplasty, Balloon / Q000295:instrumentation*; D000818:Animals; D016477:Artifacts; D001783:Blood Flow Velocity; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging* / Q000503:physiopathology; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000628:therapy; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008875:Middle Aged; D011474:Prosthesis Design; D011673:Pulsatile Flow; D015203:Reproducibility of Results; D012756:Sheep; D015607:Stents; D013599:Systole; D018616:Ultrasonography, Doppler, Duplex