title: Microbubble-augmented ultrasound declotting of thrombosed arteriovenous dialysis grafts in dogs.
abstract: OBJECTIVE
  Transcutaneous low-frequency ultrasound (LFUS) can effectively lyse clots in the presence of microbubbles. This study was designed to test the commercially available human albumin microspheres injectable suspension octafluoropropane formulation, Optison, to establish efficacy and assess US parameters of intensity and wave modes in a canine model of a thrombosed arteriovenous (dialysis) graft.
  
  
  METHODS
  Arteriovenous grafts in five dogs were cannulated, temporarily ligated, and thrombosed. Different declotting techniques were randomized to treat nine groups. Control groups involved direct saline (4.5 mL) clot injection in 0.5-1.0-mL increments. One group underwent peripheral intravenous microbubble injection (13.5 mL). Six groups underwent direct incremental clot injection of 4.5 mL of microspheres with LFUS for 30 minutes in 3-5-minute increments with use of various intensity settings in continuous-wave and pulsed-wave (PW) modes. At each increment, angiography was used to grade flow, declotting, and overall success.
  
  
  RESULTS
  One hundred four procedures showed success in all 24 high-intensity PW modes (1.2-2.0 W/cm(2)); only one of 20 control experiments was successful (P <.0001). Medium-intensity modes yielded intermediate success rates. Lowest-intensity direct-injection groups and intravenous and control groups ranked lower. Results at 30 minutes were better than at 15 minutes (P <.0001).
  
  
  CONCLUSIONS
  LFUS with direct injection of microbubbles is effective in lysing moderate-sized clots and recanalizing thrombosed arteriovenous grafts. It best succeeds at the higher range of intensity settings tested in PW mode. Further development is justified.
authors.affiliation: Department of Radiology, University of Arkansas for Medical Sciences, 4301 West Markham, Slot 556, Little Rock, Arkansas 72205-7199, USA. culpwilliamc@uams.edu
authors.forename: William C
authors.initials: WC
authors.lastname: Culp
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Porter
authors.forename: Timothy C
authors.initials: TC
authors.lastname: McCowan
authors.forename: Paula K
authors.initials: PK
authors.lastname: Roberson
authors.forename: Charles A
authors.initials: CA
authors.lastname: James
authors.forename: W Jean
authors.initials: WJ
authors.lastname: Matchett
authors.forename: Mohammed
authors.initials: M
authors.lastname: Moursi
mesh_terms: D000418:Albumins; D000818:Animals; D001166:Arteriovenous Shunt, Surgical; D001807:Blood Vessel Prosthesis; D003287:Contrast Media; D004285:Dogs; D005466:Fluorocarbons; D008863:Microspheres; D011183:Postoperative Complications; D011897:Random Allocation; D006435:Renal Dialysis; D013927:Thrombosis / Q000628:therapy*; D014464:Ultrasonic Therapy / Q000379:methods*
chemical_list: D000418:Albumins; D003287:Contrast Media; C099458:FS 069; D005466:Fluorocarbons