Reduction of vasoreactivity and thrombogenicity with laser-thermal angioplasty: comparison with balloon angioplasty

The vasoreactivity and thrombogenicity of laser-thermal angioplasty were examined and compared with those of balloon angioplasty in an atherosclerotic rabbit iliac artery. Eight rabbits underwent laser-thermal angioplasty with a 1.7-mm hot-tip probe activated at 7 W with a probe temperature of 126 +/- 19 degrees C in one iliac artery. The other iliac artery was treated with balloon angioplasty using a 2.0-mm balloon. Angiographic luminal diameter increased from 0.19 +/- 0.15 to 1.54 +/- 0.35 mm by laser and from 0.29 +/- 0.22 to 1.84 +/- 0.20 mm by balloon (P less than 0.0001, respectively). However, it decreased to 1.34 +/- 0.42 for laser and 0.45 +/- 0.39 for balloon 60 minutes later (P less than 0.0001 vs immediately post). Both iliac arteries were visualized using angioscopy, which revealed thrombotic obstruction of 91% stenosis in the ballooned artery and 8% stenosis in the lased artery. Vasoreactivity of treated vessels was also investigated. Segments 3-mm long were obtained from either treated artery or control artery and examined for noradrenaline (10 -7 M) contraction. The segments were then mounted isometrically with 1 g tension in Krebs-bicarbonate buffer. Developed tension was 0.13 +/- 0.21 g for laser thermal and 2.33 +/- 0.4 g for its control (P less than 0.0001), and 0.15 +/- 0.16 g for balloon dilatation and 2.12 +/- 0.43 g for its control (P less than 0.0001). Neither acetylcholine at 10 -6 M or papaverine at 10 -4 M induced relaxation of treated segments. Histology showed slight thermal injury at thermally-treated sites without thrombus, and intimal and medial dissection with thrombus formation at balloon dilated site.

(1) neither a laser-thermal recanalized or a balloon dilated obstructed artery is vasoreactive to constrictive or relaxant agents; and (2) laser-thermal angioplasty results in less thrombogenicity than balloon angioplasty under moderate probe temperature.