Quan K J, Hodgson J M
Department of Medicine, University Hospitals of Cleveland, Ohio, USA.
Cathet Cardiovasc Diagn. 1996 May;38(1):50-5. doi: 10.1002/(SICI)1097-0304(199605)38:1<50::AID-CCD11>3.0.CO;2-W.
Laser coronary angioplasty is a useful therapy for selected complex coronary lesions. Laser-induced acoustic trauma is postulated to be a cause of dissection and acute vessel occlusion. Controversy exists regarding the relative degree of photoacoustic effects of midinfrared and excimer lasers in clinical practice. To date, these systems have not been compared at clinical energy doses and with clinical pulsing strategies. Therefore, we studied the photoacoustic effects of both midinfrared and excimer lasing at clinically accepted doses. Human atherosclerotic iliofemoral artery segments were obtained at autopsy (n = 36) and placed lumen side up in a saline bath. Clinical laser catheters were advanced over an 0.018" guide wire, perpendicular to the tissue. A 10-g down force was applied to the catheter for full-thickness lasing. Pulsing strategies were, for midinfrared laser: 5 pulses, 1-sec pause, 5 pulses, 1-sec pause, 5 pulses, withdraw; for excimer: 5 sec of pulses, wait 10 sec, 5 sec of pulses. Several clinically acceptable energy levels were used; for excimer: 25 mJ/mm2, 40 mJ/mm2, 60 mJ/mm2; for midinfrared: 3 W (400 mJ/mm2), 3.5 W (467 mJ/mm2). Photoacoustic effect was assessed histologically by determining the number of lateral cleavage planes (dissections) arising from the lased crater border and extending into the surrounding tissue. In normal tissue, midinfrared lasing produced less acoustic damage than excimer lasing (2.79 +/- 0.78 vs. 5.27 +/- 0.75 cleavage planes, mean +/- SD, P < 0.05, data for lowest energy for each system). The same was true in noncalcified atheroma (2.48 +/- 0.71 vs. 6.43 +/- 1.09, P < 0.05) and calcified atheroma (2.47 +/- 1.21 vs. 6.27 +/- 1.13, P < 0.05). This effect was similar at all energy levels, with a trend for more damage at higher energies in both systems. This study demonstrates that midinfrared lasing causes less acoustic damage than excimer lasing when using clinical catheters, energy levels, and pulsing strategies. This effect is independent of tissue-type but tends to be dose-related. These findings may explain, in part, the differences in dissection rates seen clinically.
激光冠状动脉成形术是治疗某些复杂冠状动脉病变的有效方法。激光诱导的声学创伤被认为是夹层形成和急性血管闭塞的一个原因。关于中红外激光和准分子激光在临床实践中的光声效应的相对程度存在争议。迄今为止，尚未在临床能量剂量和临床脉冲策略下对这些系统进行比较。因此，我们研究了中红外激光和准分子激光在临床可接受剂量下的光声效应。从尸检中获取人动脉粥样硬化性髂股动脉段（n = 36），并将其管腔面朝上放置在盐水中。临床激光导管通过一根0.018英寸的导丝推进，垂直于组织。对导管施加10克的向下压力以进行全层激光照射。中红外激光的脉冲策略为：5个脉冲，1秒停顿，5个脉冲，1秒停顿，5个脉冲，回撤；准分子激光的脉冲策略为：5秒脉冲，等待10秒，5秒脉冲。使用了几种临床可接受的能量水平；准分子激光：25 mJ/mm²、40 mJ/mm²、60 mJ/mm²；中红外激光：3 W（400 mJ/mm²）、3.5 W（467 mJ/mm²）。通过确定从激光照射形成的弹坑边缘产生并延伸到周围组织的横向劈裂平面（夹层）的数量，从组织学上评估光声效应。在正常组织中，中红外激光产生的声学损伤比准分子激光少（分别为2.79±0.78和5.27±0.75个劈裂平面，平均值±标准差，P < 0.05，为每个系统最低能量的数据）。在非钙化动脉粥样硬化病变中也是如此（分别为2.48±0.71和6.43±1.09，P < 0.05）以及钙化动脉粥样硬化病变中（分别为2.47±1.21和6.27±1.13，P < 0.05）。在所有能量水平下这种效应都是相似的，两个系统中在较高能量下损伤有增加的趋势。这项研究表明，当使用临床导管、能量水平和脉冲策略时，中红外激光产生的声学损伤比准分子激光少。这种效应与组织类型无关，但倾向于与剂量相关。这些发现可能部分解释了临床上观察到的夹层发生率的差异。
