title: The effects of streptokinase and hydroxyethyl starch on in vitro clot disruption by ultrasound.
abstract: BACKGROUND
  In vitro studies showed that low-frequency ultrasound (US) causes blood clot dissolution. This effect is augmented with thrombolytics, microbubbles and microparticles. However, in animal models of transcutaneous delivery, US alone is not effective, probably due to attenuation of US energy by overlying skin. When combined with thrombolytics or microbubbles, transcutaneous US is highly effective.
  
  
  OBJECTIVE
  To assess the synergistic effect of low-intensity low-frequency US and saline, hydroxyethyl starch (HAES) (a non-gas filled microparticle containing solution), streptokinase (STK), and their combination on blood clot disruption.
  
  
  METHODS
  Human blood clots from 4 healthy donors, 2-4 hours old, were immersed for 0, 15, or 30 min in 37 degrees C in 10 ml of the above-mentioned solutions, and then were randomized to 10 sec of 20 kHz US or no US. The % difference in weight was calculated.
  
  
  RESULTS
  Immersion for 30 min without US resulted in 13.8 +/- 1.2% clot lysis in saline, and 22.0 +/- 1.3%, 21.7 +/- 2.1%, and 23.2 +/- 1.9% in STK, HAES, and STK + HAES, respectively (p = 0.002). US augmented clot lysis in all groups and at all time points. With low-intensity US, HAES was not better than saline. However, the combination of HAES + STK with US resulted in larger clot disruption at 15 sec incubation time (46.7 +/- 3.2%) than with saline (29.6 +/- 2.1%), HAES (29.6 +/- 2.5%), and STK (32.8 +/- 3.6%) (p < 0.001).
  
  
  CONCLUSIONS
  low-frequency, low-intensity US combined with HAES and STK resulted in greater clot disruption at short incubation times. This combination may assist in achieving faster reperfusion in in vivo models.
authors.affiliation: Felsenstein Research Institute and the Department of Cardiology, Rabin Medical Center, Petah-Tiqva, Israel.
authors.forename: Y
authors.initials: Y
authors.lastname: Adler
authors.forename: D
authors.initials: D
authors.lastname: Attar
authors.forename: M
authors.initials: M
authors.lastname: Vaturi
authors.forename: G
authors.initials: G
authors.lastname: Golovchiner
authors.forename: Z
authors.initials: Z
authors.lastname: Iakobishvili
authors.forename: A
authors.initials: A
authors.lastname: Battler
authors.forename: R J
authors.initials: RJ
authors.lastname: Siegel
authors.forename: Y
authors.initials: Y
authors.lastname: Birnbaum
mesh_terms: D001769:Blood / Q000000981:diagnostic imaging*; D001777:Blood Coagulation / Q000187:drug effects*; D004347:Drug Interactions; D005343:Fibrinolytic Agents / Q000494:pharmacology*; D006801:Humans; D006895:Hydroxyethyl Starch Derivatives / Q000494:pharmacology*; D013300:Streptokinase / Q000494:pharmacology*; D014463:Ultrasonography
chemical_list: D005343:Fibrinolytic Agents; D006895:Hydroxyethyl Starch Derivatives; D013300:Streptokinase