Prevosti L G, Leon M B, Smith P D, Dodd J T, Bonner R F, Robinowitz M, Clark R E, Virmani R
National Heart, Lung, and Blood Institute, Cardiology Branch, Bethesda, MD 20892.
J Thorac Cardiovasc Surg. 1988 Jul;96(1):150-6.
Acute in vitro histologic studies have shown that the pulsed xenon chloride excimer laser causes precise microablation without the surrounding thermal tissue injury associated with frequently used continuous-wave lasers such as the argon, carbon dioxide, and neodymium:yttrium aluminum garnet lasers. However, the in vivo healing response of artery wall to excimer laser injury is not known. Accordingly, a xenon chloride excimer laser (308 nm, 40 nsec pulse width, 39 mJ/mm2/pulse) was transmitted via a 600 micron fused silica fiber to create 420 craters of varying depths (30 to 270 micron) in 21 normal canine femoral and carotid arteries. At 2 hours, 2 days, 10 days, and 42 days after excimer laser ablation, the artery segments were perfusion fixed in situ and analyzed by light, scanning, and transmission electron microscopy. At 2 hours, craters were covered by a carpet of platelets and entrapped red blood cells. Fibrin and exposed collagen fibers were seen at the crater base. There was a sharp demarcation of the crater-artery wall interface without lateral laser tissue injury. At 2 days, adherent platelets persisted with thrombus covering the base of the craters. Early healing responses were present, consisting of polymorphonucleated leukocytes and new endothelial cells, which extended over the crater rims. At 10 days, no thrombi were seen, and healing continued with almost complete reendothelialization. Macrophages, fibroblasts, fibrin, and entrapped red blood cells were present below the reendothelialized surface. At 42 days, healing was complete with obliteration of the craters by fibrointimal ingrowth. The surface was completely covered by a smooth monolayer of axially aligned endothelial cells. There were no aneurysms or surface hyperplastic responses. These favorable healing responses in normal canine arteries suggest that pulsed lasers with high tissue absorption coefficients, such as the xenon chloride excimer laser, may be suitable energy sources for clinical laser angioplasty procedures. However, further studies in atherosclerotic animals are required before human clinical responses can be accurately predicted.
急性体外组织学研究表明，脉冲氯化氙准分子激光可造成精确的微消融，而不会像常用的连续波激光（如氩激光、二氧化碳激光和钕：钇铝石榴石激光）那样对周围组织造成热损伤。然而，动脉壁对准分子激光损伤的体内愈合反应尚不清楚。因此，通过一根600微米的熔融石英光纤传输氯化氙准分子激光（波长308纳米，脉冲宽度40纳秒，能量密度39毫焦/平方毫米/脉冲），在21条正常犬的股动脉和颈动脉中制造了420个深度各异（30至270微米）的弹坑。在准分子激光消融后的2小时、2天、10天和42天，将动脉段原位灌注固定，并用光学显微镜、扫描电子显微镜和透射电子显微镜进行分析。在2小时时，弹坑被一层血小板和截留的红细胞覆盖。在弹坑底部可见纤维蛋白和暴露的胶原纤维。弹坑与动脉壁界面界限清晰，无激光对周围组织的侧向损伤。在2天时，附着的血小板持续存在，血栓覆盖弹坑底部。出现了早期愈合反应，包括多形核白细胞和新的内皮细胞，它们延伸至弹坑边缘。在10天时，未见血栓，愈合继续，几乎完全重新内皮化。巨噬细胞、成纤维细胞、纤维蛋白和截留的红细胞出现在重新内皮化表面下方。在42天时，愈合完成，弹坑被纤维内膜向内生长所闭塞。表面完全被一层轴向排列的光滑单层内皮细胞覆盖。未出现动脉瘤或表面增生反应。正常犬动脉中这些良好的愈合反应表明，具有高组织吸收系数的脉冲激光，如氯化氙准分子激光，可能是临床激光血管成形术合适的能量来源。然而，在准确预测人体临床反应之前，还需要对动脉粥样硬化动物进行进一步研究。
