Laser angioplasty: controlled delivery of argon laser energy

A laser catheter system that integrates balloon and fiberoptic technologies was evaluated. In vitro tissue studies were conducted to compare the tissue response to laser irradiation from a bare optical fiber (undiverged light beam) and from a fiber with an optical assembly (diverged light beam). An in vivo study of occluded and unoccluded canine femoral arteries examined coaxial alignment of the diverged light beam and the resultant thermal effects. In the in vitro studies, a diverged laser light beam effected maximum tissue ablation (mean crater diameter, 1.81 mm +/- 0.44) at a distance of only 3 mm from the optical fiber tip. The in vivo study demonstrated the ability of a specially designed balloon catheter to align the diverged laser beam coaxially within the arterial lumen. This laser catheter system successfully avoids the risks of inadequate tissue removal and perforation.