Effectiveness of transcranial and transthoracic ultrasound and microbubbles in dissolving intravascular thrombi

Objective. To examine the effectiveness of 1-MHz and 40-kHz ultrasound with and without microbubbles in fragmenting thrombi in attenuated conditions. Methods. First, an vitro transcranial model was used to examine the ability of these frequencies to-fragment thrombi in the presence or absence of per fluorocarbon-exposed sonicated dextrose albumin microbubbles. Second, an in vivo transthoracic model was used to test the effectiveness of these same frequencies with intravenous perfluorocarbon-exposed sonicated dextrose alb umin in fragmenting left circumflex coronary thrombotic occlusions. Results . In the in vitro model, both transcranial 1-MHz and 40-kHz ultrasonic freq uencies were effective at fragmenting thrombi only in the presence of micro bubbles. In the in vivo model, 1-MHz ultrasound with intravenous perfluoroc arbon-exposed sonicated dextrose albumin angiographically recanalized only 4 of 14 occlusions but was consistently effective at improving myocardial b lood flow to the risk area even in the absence of angiographic recanalizati on. Both 40-kHz and 1-MHz ultrasound with perfluorocarbon-exposed sonicated dextrose albumin improved regional wall-thickening and electrocardiographi c abnormalities (P < .05 compared with control or ultrasound alone). Conclu sions. Transcranial and transthoracic ultrasound in the presence of Intrave nous microbubbles can improve flow to Ischemic regions and should be consid ered as a supplement to current pharmacologic therapy.