title: Cooling System Permits Effective Transcutaneous Ultrasound Clot Lysis In Vivo Without Skin Damage.
abstract: Previous in vivo studies have shown that transcutaneous ultrasound enhances clot dissolution in the presence of either streptokinase or microbubbles. However, ultrasound-induced skin damage has been a major drawback. The objective was to evaluate the effect of a cooling system to prevent the skin damage that has heretofore been associated with transcutaneous low-frequency, high-intensity ultrasound clot dissolution. After thrombi were induced in both iliofemoral arteries in 15 rabbits, streptokinase (25,000 U/kg) was given intravenously and dodecafluoropentane was injected slowly (2 mL/15 min) through an infusion catheter into the abdominal aorta. One iliofemoral artery was randomized to receive ultrasound treatment, and the contralateral artery was treated as a control (receiving streptokinase and dodecafluoropentane alone). In six rabbits (group 1), the skin below the ultrasound transducer was protected by the use of a balloon cooling system, and in the other nine rabbits (group 2), ultrasound was used without a cooling system. Seven of nine (78%) arteries treated without the cooling system, and six of six (100%) arteries treated with the cooling system were angiographically recanalized after ultrasound + streptokinase + dodecafluoropentane treatment. Thermal damage was present in the skin and soft tissues of all nine rabbits treated without a cooling system. However, the skin and soft tissues were grossly and histologically normal in the six rabbits in which the transcutaneous ultrasound was used with the cooling system. Low-frequency, high-intensity ultrasound energy can be delivered transcutaneously for clot dissolution without concomitant tissue damage when coupled with the use of a cooling system to prevent thermal injury.
authors.affiliation: Division of Cardiology, Cedars-Sinai Medical Center, Los Angeles, California.
authors.initials: H
authors.lastname: Luo
authors.initials: MC
authors.lastname: Fishbein
authors.initials: Y
authors.lastname: Bar-Cohen
authors.initials: T
authors.lastname: Nishioka
authors.initials: H
authors.lastname: Berglund
authors.initials: CJ
authors.lastname: Kim
authors.initials: T
authors.lastname: Nagai
authors.initials: Y
authors.lastname: Birnbaum
authors.initials: RJ
authors.lastname: Siegel