Development of intravascular shock wave thrombolysis for cerebral embolism

随着扩散磁共振成像和单光子发射计算机断层扫描等先进的神经影像学技术的发展，脑梗死患者在发病后数小时内就可以被检测出来。由于脑梗死的治疗时间窗一般被认为在几小时之内，因此需要尽快用少量的纤溶药物实现闭塞脑动脉的再通，利用气泡与冲击波相互作用诱导的液体射流在体外成功地实现了纤溶。为了进一步完善这项技术，使其更好地应用于临床，我们选用了Q开关脉冲钬激光器。该激光器具有200 ns的脉冲持续时间和2.1 mm的波长。该激光器的能量范围从36到150 mJ/脉冲可变。激光束通过直径为0.6mm的光纤传输。在本实验中，这种激光以86 mJ/脉冲照射水中，引起超过100 atm的强冲击波， ...更多信息 瞬时球形气泡，可穿透人工血栓形成射流。为了获得更强的冲击波和更大的气泡，制备并研究了具有三种类型端面的光纤：凸透镜、粗糙平面和光滑平面。具有凸透镜形端部的光纤产生的冲击波比其他端部的冲击波具有更强的超压和更大的气泡。对于两个平坦端面，光滑端面和粗糙端面的冲击波超压和气泡体积没有差异，在直径为4 mm的玻璃管中观察到了激光诱导气泡。气泡逐渐膨胀，在约1 ms时达到最大尺寸，而大容器中的气泡在约300 μs时达到最大尺寸。在此基础上，尝试了叠氮化银爆炸产生的冲击波与激光诱导的最大气泡的相互作用。气泡被转化为液体射流，其可以比仅激光诱导的气泡更深地穿透人造血栓。少

As advancing neurological images such as diffusion magnetic resonance imaging and single photon emission computed tomography, the patients having cerebral infarction within several hours after onset have been detectable. Since the therapeutic time window of cerebral infarction is generally thought to be within several hours, it is necessary to accomplish recanalization of occluded cerebral arteries with a little fibrinolytics as soon as possible.Fibrinolysis with a liquid jet induced by interaction between bubble and shock wave was succeeded in-vitro. In order to improve this technology for clinical application, A Q-switch pulsed Holmium : YAG laser was selected. This laser had 200 ns pulse duration and 2.1 mm wavelength. Energy range of this laser was variable from 36 to 150 mJ/pulse. The laser beam was transmitted through an optical fiber which diameter was 0.6 mm. In the present experiment, this laser irradiation at 86 mJ/pulse in water induced a strong shock wave over 100 atm and a … More transient spherical bubble, which can penetrate into an artificial thrombus forming a jet. In order to obtain a stronger shock wave and a larger bubble, optical fibers with three types of end surface ; a convex-lens, a coarse flat, and smooth flat were prepared and studied. The optical fiber with a convex lens-shaped end produced a shock wave with stronger overpressure and a larger bubble than that of the other ends. Regarding to two flat end surfaces, there was no difference in overpressure of a shock wave and bubble volume between smooth and coarse.A laser-induced bubble in a glass tube which diameter was 4mm was observed. The bubble gradually expanded and reached at maximum size at about 1 ms while a bubble in a large vessel did at about 300 μs. Based on this result, interaction between a shock wave induced by silver azide explosion and the laser-induced maximum bubble was attempted. The bubble was transformed to a liquid jet, which could penetrate into an artificial thrombus more deeply than only a laser-induced bubble did. Less