Viator J A, Prahl S A
Oregon Graduate Institute, Portland, Oregon 97291, USA.
Lasers Surg Med. 1999;25(5):379-88. doi: 10.1002/(sici)1096-9101(1999)25:5<379::aid-lsm3>3.0.co;2-b.
Laser thrombolysis is a means for clearing blood clots in occluded arteries. Many researchers have studied the mechanisms of clot ablation, and research clinicians have used the technique to treat myocardial infarction with a number of different laser systems. Specifically, a 1-microsec pulsed dye laser has been used clinically to remove blood clots in coronary arteries. As a comparative study, the ablation characteristics of lasers with pulse durations in the ranges of 50-150 microsec and 2-10 msec were investigated. Two frequency-doubled Nd:YAG lasers at 532 nm were used in this study. Ablation threshold and ablation efficiency of gel phantoms and thrombus using these two lasers were measured and compared with the results of the pulsed dye laser. The pulsed dye laser in this study operated at 522 nm.
STUDY DESIGN/MATERIALS AND METHODS: Gelatin samples with 150 cm(-1) absorption coefficient at 532 nm and animal clot were confined to 3-mm silicone tubes to measure ablation parameters. Additional samples with 150 cm(-1) absorption coefficient at 522 nm were prepared for use with the pulsed dye laser. A fluorescence technique and photographic bubble detection were used to determine ablation threshold. A spectrophotometric technique was used to determine ablation efficiency.
The ablation threshold of the gel phantoms for all three lasers was determined to be 17 +/- 2 mJ/mm(2). Ablation efficiency for the gel phantoms was 1.7 +/- 0.1 microg/mJ. Clot had an ablation efficiency of 2.9 +/- 1.0 microg/mJ.
Ablation threshold and efficiency are independent of laser pulse duration for 1-microsec, 50-150-microsec, and 2-10-msec pulses (P < 0.05).
激光溶栓是清除阻塞动脉中血凝块的一种方法。许多研究人员研究了血栓消融的机制，临床研究人员已使用该技术通过多种不同的激光系统治疗心肌梗死。具体而言，1微秒脉冲染料激光已在临床上用于清除冠状动脉中的血凝块。作为一项对比研究，对脉冲持续时间在50 - 150微秒和2 - 10毫秒范围内的激光的消融特性进行了研究。本研究使用了两台532纳米的倍频Nd:YAG激光。测量了使用这两种激光对凝胶体模和血栓的消融阈值及消融效率，并与脉冲染料激光的结果进行了比较。本研究中的脉冲染料激光工作波长为522纳米。
研究设计/材料与方法：将在532纳米处吸收系数为150 cm⁻¹的明胶样品和动物血凝块置于3毫米的硅胶管中以测量消融参数。另外制备了在522纳米处吸收系数为150 cm⁻¹的样品用于脉冲染料激光。采用荧光技术和摄影气泡检测来确定消融阈值。采用分光光度技术来确定消融效率。
所有三种激光对凝胶体模的消融阈值确定为17±2 mJ/mm²。凝胶体模的消融效率为1.7±0.1 μg/mJ。血凝块的消融效率为2.9±1.0 μg/mJ。
对于1微秒、50 - 150微秒和2 - 10毫秒的脉冲，消融阈值和效率与激光脉冲持续时间无关（P < 0.05）。
