title: Ultrasound thrombolysis in hemodialysis access: in vitro investigation.
abstract: OBJECTIVE
  To evaluate the effectiveness of ultrasound thrombolysis in occluded hemodialysis access shunts using an in vitro model.
  
  
  METHODS
  Thrombosed hemodialysis accesses were simulated by clotted bovine blood in a flow model (silicone tubing; inner diameters 4, 6, and 9 mm). After retrograde and antegrade sheath placement (7 Fr), mechanical thrombolysis was performed using an ultrasound probe (Acolysis, Angiosonics, Morrisville, NC, USA). The tip of the device measured 2.2 mm in diameter. During sonication, the catheter was moved slowly back and forth using an over-the-wire system. Thirty complete occlusions [tubing diameters 4 mm (n = 12), 6 mm (n = 12), 9 mm (n = 6)] were treated. Initial thrombus weights were 3.5 (+/- 0.76) g, 7.7 (+/- 1.74) g, and 19.4 (+/- 2.27) g for the three diameters. Maximum sonication time was 15 min for each probe.
  
  
  RESULTS
  With this device, we were able to restore a continuous lumen in all 12 occluded 4 approximately mm silicone tubes. No wall-adherent thrombi remained after sonication for 3.5--9.6 min. In hemodialysis access models with diameters of 6 mm, thrombus fragments persisted in 25% (3/12 accesses). These were located in the medial portion of the access loop and near to the puncture sites. However, flow was re-established after 5.0--13.0 min of treatment in all settings. Mechanical dissolution of thrombus material failed in five of six access models with diameters of 9 mm, even though ultrasound energy was applied for the maximum of 15 min.
  
  
  CONCLUSIONS
  In a clotted hemodialysis shunt model, successful ultrasound thrombolysis was limited to small access diameters and small amounts of thrombus.
authors.affiliation: Department of Diagnostic Radiology, University of Technology Aachen, Pauwelsstrasse 30, D-52057 Aachen, Germany. wildberg@rad.rwh-aachen.de
authors.forename: J E
authors.initials: JE
authors.lastname: Wildberger
authors.forename: T
authors.initials: T
authors.lastname: Schmitz-Rode
authors.forename: P
authors.initials: P
authors.lastname: Haage
authors.forename: J
authors.initials: J
authors.lastname: Pfeffer
authors.forename: A
authors.initials: A
authors.lastname: Ruebben
authors.forename: R W
authors.initials: RW
authors.lastname: Günther
mesh_terms: D004867:Equipment Design; D005240:Feasibility Studies; D006435:Renal Dialysis; D015912:Thrombolytic Therapy / Q000295:instrumentation / Q000379:methods*; D014464:Ultrasonic Therapy