Study on Thrombolysis Using Small Ultrasound Vibration.

有研究表明，利用直径3mm的超声针尖，在超声频率为20KHz，功率为1w的条件下，对体外制造的血凝块进行超声照射，使其破裂。在水浴中测试了几种自制的薄型换能器的功率。利用微泡扩散溶液可以直观地显示超声功率在水中的方向和大小。在调整超声频率使其效果最大化后，应用换能器检测换能器是否能在体外促进溶栓。超声放射线联合尿激酶治疗的血块干重明显小于单独使用尿激酶的血块干重。这种超声效应在微泡存在下增强，可能是由于空化现象。需要长寿命的微气泡，而普通微气泡容易溶解到水或血液中。以十二氟戊烷为原料，研制了一种新型稳定微泡剂。犬用超声心动图检查其耐久性。外周静脉注射十二氟戊烷溶液，观察心肌混浊情况。剂量大于0.5ml/kg时，心肌明显混浊时间长，可达10 ~ 50分钟。结论超声微换能器与微泡联合使用可提高体内溶栓效果。

It has been revealed that blood clot made in vitro was broken by ultrasound radiation from the ultrasound tip as thin as 3mm in diameter, in which the ultrasound frequency was 20KHz and the power was 1 Watt. Several self-made thin transducer was examined its power in a water bath. Direction and magnitude of the ultrasound power in the water could be visualized using solution diffused by microbubbles. After adjusting the ultrasound frequency to be maximize its effect, the transducer was applied to examine whether the transducer could enhance the thrombolysis in vitro. Dry weight of the clot was less by combination use of ultrasound radiation and Urokinase than that by sole use of Urokinase. This ultrasound effect is enhanced under presence of microbubbles, probably due to cavitation phenomenon. Long-life microbubbles are needed, while ordinal microbubbles are easy to be solved into water or blood. We developed a new agent of stable microbubbles, which was made from dodecafluoropentane. Its durability was examined in canines by echocardiography. The solution of dodecafluoropentane was injected into the peripheral vein and the myocardial opacification was evaluated. Using a dosage over 0.5ml/kg, the myocardium was clearly opacified for long period as over 10 to 50 minutes. Weconclude that the combination use of microtransducer of ultrasound and microbubbles will enhance the thrombolysis in vivo.