Pioneered several years ago by cardiologists and interventional radiologists, laser-assisted angioplasty for the ablation of occlusive atherosclerotic lesions in the peripheral and coronary circulations is now entering the domain of the vas cular surgeon, who has the ability to progress beyond the limitations of the percutaneous approach.In the initial 38 patients undergoing 51 lower extremity laser angioplasty/ balloon dilatation procedures for peripheral vascular occlusive disease, pedal pulses were restored in 32 (63%) limbs. The tandem procedure failed in 16 (31%); however, when improvement was assessed objectively by postoperative ankle/arm index evaluation, a positive outcome was achieved in 72 % of the patients. Three (6%) patients required femoral-popliteal bypass after balloon- related arterial dissection was identified.Although laser angioplasty can successfully open occluded arteries, new in traoperative angiographic equipment compatible with laser angioplasty and a variety of incrementally siz...

Argon Laser-Assisted Peripheral Angioplasty

Vascular applications of lasers.

Blood may limit laser ablation of arterial plaque by decreasing thermal energy transfer from metal-capped probes to arterial occlusions. Since a gas is a good insulator of heat, CO2 may be a better medium for laser recanalization. To study this possibility, a metal-capped fiber was positioned in a segment of blood-filled polyethylene tubing and activated with an argon laser. Probe temperatures were measured in blood and as the blood was displaced by flowing CO2 gas. Probe temperatures were higher at all powers studied in CO2 gas than in blood. Maximum probe temperatures averaged 518 +/- 24 degrees C after CO2 infusion versus 320 +/- 7 degrees C in blood, (P less than 0.0001). Blood aggregate formation was noted on the probe surface in blood but not in CO2 medium. Thus CO2 gas may be a preferable medium for laser recanalization, since higher probe temperatures are achieved, and the probe surface remains free of insulating blood coagulate.

Effect of CO2 and blood media on laser probe temperature.

The effects of laser energy on the arterial wall

Differential effects of Nd-YAG laser on collagen and elastin production by chick embryo aortae in vitro. Relevance to laser angioplasty for removal of atherosclerotic plaques.

The primary concerns in the development of a laser catheter for intravascular use are the potential hazards of vessel wall perforation and distal embolization. We present evidence, using technetium 99-labeled thrombi in two rabbit aortas and one human cadaver coronary artery, that distal embolization does not occur after argon laser recanalization. Also, no vessel wall perforation was observed during recanalization of 15 thrombosed rabbit aortas and 1 inferior vena cava, used because of their extremely thin walls. Laser recanalization of three peripheral arteries with atherosclerotic plaque obstruction, in amputated human legs, snowed no evidence of vessel wall perforation.



The incidence of vessel wall perforation can be minimized by preferential use of the argon laser, strict maintainence of a coaxial relationship between the laser catheter and the vessel, and exercising care during the actual lasing process.



Distal embolization does not appear to be an important consideration.

Phillipe Quilici

Papers

Embolization and vessel wall perforation in argon laser recanalization.