Transluminal laser treatment with metal-capped optical fibres of normal coronary arteries in live dogs: an angiographic and histological study of the acute effects

Transluminal laser treatment of coronary arteries with bare optical fibres frequently results in perforation, mainly owing to misalignment of the laser beam. To overcome this problem, a 300 μm-diameter optical fibre, fitted with a 1.5 mm metal cap, was used to convert argon-laser energy to heat. In 12 anaesthetized dogs, a 8.3 French Sones guiding catheter was placed, via the right carotid artery, in the left coronary ostium, and the optical fibre was advanced into the circumflex artery. After argon laser treatment at 6 W for 1s, the fibre was withdrawn by increments of 0.5–1.0 cm; laser treatment was repeated after each repositioning, by using 6W and increasing exposure times of 2, 3, 4 and 5 s. In six dogs the laser was applied in the beating heart, and in six in the asystolic heart, to assess the effects in the absence of a coronary blood flow. Angiography, before and after the laser treatment, did not reveal coronary perforation or other major acute complications. Post-mortem examination showed that the number of sites with evidence of intimal vaporization was higher in dogs treated in the asystolic heart than in the others (14 versus 6 sites, respectively,P<0.02). The post mortems confirmed that perforation did not occur in either case. Laser treatment for 5 s resulted in intimal vaporization in 11 of the 12 arteries (91%); for 4s in seven of the arteries (60%); and for 3 s in two arteries (16%). Thus, intimal vaporization of normal coronary arteries in both the beating and the asystolic dog heart can be achieved without perforation or other major acute complications by transluminal laser treatment with metal-capped optical fibres.