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Stroke. 2013 Dec;44(12):3376-81. doi: 10.1161/STROKEAHA.113.002713. Epub 2013 Oct 24.

CLOTBUST-Hands Free: pilot safety study of a novel operator-independent ultrasound device in patients with acute ischemic stroke.

Author information

  • 1From the Department of Neurology, Stroke Program (A.D.B., L.S., A.W.B., P.S., H.I., N.R.G., S.I.S., J.C.G.) and Center for Clinical and Translational Sciences (H.P., M.A.-H., R.P., M.H.R.), University of Texas Health Science Center at Houston, TX; Comprehensive Stroke Center, Department of Neurology, The University of Alabama at Birmingham (A.V.A., A.S.); and Department of Neurology, Dresden University Stroke Center, University of Technology Dresden, Dresden, Germany (K.B.).

Erratum in

  • Stroke. 2014 Jan;45(1):e11.



The Combined Lysis of Thrombus in Brain Ischemia With Transcranial Ultrasound and Systemic T-PA-Hands-Free (CLOTBUST-HF) study is a first-in-human, National Institutes of Health-sponsored, multicenter, open-label, pilot safety trial of tissue-type plasminogen activator (tPA) plus a novel operator-independent ultrasound device in patients with ischemic stroke caused by proximal intracranial occlusion.


All patients received standard-dose intravenous tPA, and shortly after tPA bolus, the CLOTBUST-HF device delivered 2-hour therapeutic exposure to 2-MHz pulsed-wave ultrasound. Primary outcome was occurrence of symptomatic intracerebral hemorrhage. All patients underwent pretreatment and post-treatment transcranial Doppler ultrasound or CT angiography. National Institutes of Health Stroke Scale scores were collected at 2 hours and modified Rankin scale at 90 days.


Summary characteristics of all 20 enrolled patients were 60% men, mean age of 63 (SD=14) years, and median National Institutes of Health Stroke Scale of 15. Sites of pretreatment occlusion were as follows: 14 of 20 (70%) middle cerebral artery, 3 of 20 (15%) terminal internal carotid artery, and 3 of 20 (15%) vertebral artery. The median (interquartile range) time to tPA at the beginning of sonothrombolysis was 22 (13.5-29.0) minutes. All patients tolerated the entire 2 hours of insonation, and none developed symptomatic intracerebral hemorrhage. No serious adverse events were related to the study device. Rates of 2-hour recanalization were as follows: 8 of 20 (40%; 95% confidence interval, 19%-64%) complete and 2 of 20 (10%; 95% confidence interval, 1%-32%) partial. Middle cerebral artery occlusions demonstrated the greatest complete recanalization rate: 8 of 14 (57%; 95% confidence interval, 29%-82%). At 90 days, 5 of 20 (25%, 95% confidence interval, 7%-49) patients had a modified Rankin scale of 0 to 1.


Sonothrombolysis using a novel, operator-independent device, in combination with systemic tPA, seems safe, and recanalization rates warrant evaluation in a phase III efficacy trial.



CLOTBUST; operator-independent device; reperfusion; sonothrombolysis; stroke; thrombolytic therapy; ultrasonography, doppler, transcranial

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