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°C in one iliac artery. The other iliac artery was treated with balloon angioplasty irsing a 2.0mm 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 < 0.0001. respectively). However, it decreased to 1.34 ± 0.42 for laser and 0.45 ± 0.39 for balloon 60 minutes later (P < 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 isotnetrically 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 < 0.0001), and 0.15 ± 0.16 g for balloon dilatation and 2.12 ± 0.43 g for its control (P < 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. In conclusion: (1) neither a laser‐thermal recanalized or a balloon dilated obstructed artery is vasoreactive to constrictive or relaxant agents; and (2) laser‐thermal angioplase results in less thrombogenicity than balloon angioplasty under moderate probe temperature.