title: Treatment of deeply located acute intravascular thrombi with therapeutic ultrasound guided by diagnostic ultrasound and intravenous microbubbles.
abstract: OBJECTIVE
  We sought to determine the added value of simultaneous imaging of intravenously infused microbubbles that are being used to dissolve an intravascular thrombus with therapeutic ultrasound (TUS).
  
  
  METHODS
  In a chronic canine arteriovenous graft occluded by a thrombus, TUS (1 MHz) was applied through a 6-cm-thick tissue-mimicking phantom (measured mean +/- SD peak negative pressure through the phantom, 958 +/- 104 kPa) during an intravenous infusion of either saline (n = 6 occlusions) or lipid-encapsulated microbubbles (ImaRx Therapeutics, Inc, Tucson, AZ). Therapeutic ultrasound was intermittently applied during the microbubble infusion either at set time intervals (n = 6 occlusions) or when simultaneous diagnostic ultrasound (DUS) indicated a sustained presence of microbubbles (n = 12 occlusions). Success was defined as return of rapid flow within the graft (grade 3 flow).
  
  
  RESULTS
  Diagnostic ultrasound showed microbubbles moving through small channels within the thrombus before angiographic evidence of flow in the graft. This guided the timing of TUS application better than using set time intervals. Angiographic clearance of the thrombus and restoration of grade 3 flow at 45 minutes of treatment were seen in 33% of deeply located thrombosed grafts treated with TUS at set time intervals and 92% of grafts treated with TUS guided by DUS (P < .001 compared with set time intervals).
  
  
  CONCLUSIONS
  The use of TUS with intravenous microbubbles has a high success rate in recanalizing deeply located thrombosed arteriovenous grafts when performed with DUS guidance.
authors.affiliation: Department of Internal Medicine, Section of Cardiology, University of Nebraska Medical Center, 981165 Nebraska Medical Center, Omaha, 68198-1165 USA.
authors.forename: Jeane M
authors.initials: JM
authors.lastname: Tsutsui
authors.forename: Feng
authors.initials: F
authors.lastname: Xie
authors.forename: Jason
authors.initials: J
authors.lastname: Johanning
authors.forename: John
authors.initials: J
authors.lastname: Lof
authors.forename: Brian
authors.initials: B
authors.lastname: Cory
authors.forename: Amming
authors.initials: A
authors.lastname: He
authors.forename: Lewis
authors.initials: L
authors.lastname: Thomas
authors.forename: Terry
authors.initials: T
authors.lastname: Matsunaga
authors.forename: Evan
authors.initials: E
authors.lastname: Unger
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Porter
mesh_terms: D000792:Angiography; D000818:Animals; D016009:Chi-Square Distribution; D004285:Dogs; D006083:Graft Occlusion, Vascular / Q000000981:diagnostic imaging* / Q000628:therapy*; D007262:Infusions, Intravenous; D045423:Microbubbles; D019047:Phantoms, Imaging; D018709:Statistics, Nonparametric; D013927:Thrombosis / Q000000981:diagnostic imaging* / Q000628:therapy*; D014464:Ultrasonic Therapy; D018084:Ultrasonography, Interventional