An orderly approach: comments on the intravascular use of lasers

Endovascular Excimer Laser Atherectomy Techniques to Treat Complex Peripheral Vascular Disease: An Orderly Process

Peripheral vascular disease represents the largest obstructive subsegment within the vascular system. Advances in equipment, techniques, biochemical treatments, and the influx of multiple specialties into this arena indicate a coming tidal wave of change to the standard treatment plan for patients with claudication and especially critical limb ischemia. Initial attempts in the 1980s to utilize the "laser" to treat peripheral vascular disease led to a clinical debacle: wavelengths and methods were not optimized; tissue heating was excessive, resulting in restenosis. Since then the "laser" has fallen from grace for endovascular treatment, although it has an infinite set of potential wavelengths, energy levels, and delivery methods. The xenon chloride, excimer laser, a pulsed 308-nm system, has overcome many of these early catastrophes. The long, ongoing success of this method of photoablating thrombus and plaque represents a true step forward in the endovascular treatment of occlusive disease. Although only a tool, the excimer laser provides a means to utilize electromagnetic energy instead of shearing mechanical force to resolve occlusions. With its active element at the tip, the excimer laser requires much less mechanical translation force to cross total occlusions, find the distal lumen, and thereby cause less plaque destabilization. In addition, removing the firm surface layer of plaque, decapping, and some of the plaque volume, debulking, exposes the softer subsegments of the plaque to balloon angioplasty. Utilizing this method, more complex lesions can be approached safely, with a high likelihood of successful revascularization and a low risk of potentially limb-threatening complication.

CO2-laser radiation damage of the arterial wall

This study describes the effects of CO2 laser radiation on the histology of the normal rabbit arterial wall, using models that simulate laser angioplasty and anastomosis. Rabbit arteries were exposed to laser treatments similar to those used clinically; 40, 0.5 sec pulses of 40-60 mW, CO2 continuous wavelength laser, or a 1/2-circumferential laser anastomosis with a 60-80 mW continuous pulse. Aneurysms developed in 8 of 22 femoral, 1 of 22 carotid, and no controls at 12 week. There were small breaks in the internal elastic lamina with atrophy, loss of muscularis, "packing" of the elastica, thinning of the muscularis at the damage site, and enlargement of the arterial diameter. Aneurysms developed in one femoral and no carotid anastomosed artery. Laser anastomoses demonstrated more muscle damage and loss, with extensive scarring and a wider area of elastic loss than the controls. The intima was reestablished with focal reduplication of the internal elastic lamina. There were no histologic differences between the arteries which developed aneurysms and those which did not in either series. These results suggest that low power laser damage of the arterial wall consists mainly of destruction of the muscularis propria, with minimal damage to the elastica.