![]() 2,4-9 The mechanisms of ultrasound-enhanced thrombolysis include improved drug transport, reversible alteration of the fibrin structure, and increased binding of t-PA to fibrin 2,4-9 when ultrasound frequencies ranging from kilohertz to those used in diagnostic ultrasonography are used. In experimental models, ultrasound has been shown to facilitate the activity of fibrinolytic agents within minutes of its exposure to a thrombus and to blood that contains t-PA. 2,3 Successful thrombolysis depends on the delivery of t-PA to the thrombus through residual blood flow around the arterial obstruction. 1 Major reasons for incomplete recovery include a severe initial ischemic insult and slow and incomplete thrombolysis. Half of patients who have had ischemic stroke remain moderately or severely disabled despite treatment with intravenous tissue plasminogen activator (t-PA). In patients with acute ischemic stroke, continuous transcranial Doppler augments t-PA-induced arterial recanalization, with a nonsignificant trend toward an increased rate of recovery from stroke, as compared with placebo. At three months, 22 of 53 patients in the target group who were eligible for follow-up analysis (42 percent) and 14 of 49 in the control group (29 percent) had favorable outcomes (as indicated by a score of 0 to 1 on the modified Rankin scale) (P=0.20). Twenty-four hours after treatment of the patients eligible for follow-up, 24 in the target group (44 percent) and 21 in the control group (40 percent) had dramatic clinical recovery (P=0.7). Complete recanalization or dramatic clinical recovery within two hours after the administration of a t-PA bolus occurred in 31 patients in the target group (49 percent), as compared with 19 patients in the control group (30 percent P=0.03). Symptomatic intracerebral hemorrhage occurred in three patients in the target group and in three in the control group. ResultsĪ total of 126 patients were randomly assigned to receive continuous ultrasonography (63 patients) or placebo (63 patients). Secondary end points included recovery at 24 hours, a favorable outcome at three months, and death at three months. The primary combined end point was complete recanalization as assessed by transcranial Doppler ultrasonography or dramatic clinical recovery. The patients were randomly assigned to receive continuous 2-MHz transcranial Doppler ultrasonography (the target group) or placebo (the control group). We treated all patients who had acute ischemic stroke due to occlusion of the middle cerebral artery with intravenous t-PA within three hours after the onset of symptoms. Our objective was to determine whether ultrasonography can safely enhance the thrombolytic activity of t-PA. Transcranial Doppler ultrasonography that is aimed at residual obstructive intracranial blood flow may help expose thrombi to tissue plasminogen activator (t-PA). The most trusted, influential source of new medical knowledge and clinical best practices in the world. Information and tools for librarians about site license offerings. Valuable tools for building a rewarding career in health care. The authorized source of trusted medical research and education for the Chinese-language medical community. The most advanced way to teach, practice, and assess clinical reasoning skills. Information, resources, and support needed to approach rotations - and life as a resident. ![]() The most effective and engaging way for clinicians to learn, improve their practice, and prepare for board exams. NEW! Peer-reviewed journal featuring in-depth articles to accelerate the transformation of health care delivery.Ĭoncise summaries and expert physician commentary that busy clinicians need to enhance patient care. NEW! A digital journal for innovative original research and fresh, bold ideas in clinical trial design and clinical decision-making.
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