Effects of argon laser on vascular materials

Abstract

The laser has been shown to vaporize arterial atheromatous plaque, but little information is available about its effect on various vascular materials. This study attempts to determine a safe margin for laser graft thrombectomy. An 18 watt argon laser with a 2 mm metalencased sapphire tip fiberoptic system was used. Specimens such as autogenous vein, polytetrafluoroethylene (PTFE), and Dacron grafts as well as polypropylene and PTFE sutures were harvested from amputated human legs. Laser energy was delivered from the tip of the fiberoptic system while perpendicular to and in direct contact with these materials. The effects were examined histologically and compared by determining the bursting pressure of the grafts and the breaking strength of the sutures. The results indicate that seven sections of autogenous vein grafts and 11 sections of PTFE grafts were perforated by laser delivery of 32.9 ± 9.9 and 50.0 ± 7.1 joules, respectively, whereas two sections of Dacron grafts were easily perforated after only 10 joules was delivered. The bursting pressure of PTFE and autogenous vein grafts after laser application was determined to be more than 300 mm Hg. The breaking strength of 6-0 PTFE sutures was compared before and after receiving 200 joules by contact laser application. No significant difference was found; in a before laser application the breaking strength was 585.0 ± 9.6 gm compared with 560.0 ± 16.4 gm after laser application (n = 4, p > 0.1). However, 6-0 polypropylene sutures were easily melted after receiving 10 joules of laser energy. Our experience indicates that the use of argon laser against PTFE grafts or autogenous vein grafts can result in perforation but is less hazardous than that against Dacron grafts and polypropylene sutures. Laser application had little effect on the strength of PTFE sutures.