Initial results and subsequent outcome of laser thermal-assisted balloon angioplasty of 56 consecutive femoropopliteal lesions

Pulsed laser and thermal ablation of atherosclerotic plaque: morphometrically defined surface thrombogenicity in studies using an annular perfusion chamber

Although clinical trials using laser and thermal angioplasty devices have been underway, the effects of pulsed laser and thermal ablation of atherosclerotic plaque on surface thrombogenicity are poorly understood. This study examined the changes in platelet adherence and thrombus formation on freshly harvested atherosclerotic aorta segments from Watanabe-heritable hyperlipidemic rabbits after ablation by two pulsed laser sources (308-nm xenon chloride excimer and 2,940-nm erbium:yttrium-aluminum-garnet [YAG] lasers) and a prototype catalytic hot-tip catheter. Specimens were placed in a modified Baumgartner annular chamber and perfused with citrated whole human blood, followed by quantitative morphometric analysis to determine the percent surface coverage by adherent platelets and thrombi in the treated and contiguous control areas. Pulsed excimer laser ablation of plaque did not change platelet adherence or thrombus formation in the treated versus control zones. However, photothermal plaque ablation with a pulsed erbium:YAG laser resulted in a 67% reduction in platelet adherence, compared with levels in control areas (from 16.7 +/- 2.2% to 5.5 +/- 1.8%; p less than 0.005). Similarly, after plaque ablation using a catalytic thermal angioplasty device, there was a 74% reduction in platelet adherence (from 29.2 +/- 5.1% to 7.7 +/- 1.6%; p less than 0.005) and a virtual absence of platelet thrombi (from 8.6 +/- 2.3% to 0.03 +/- 0.03%; p less than 0.005). This reduced surface thrombogenicity after plaque ablation with either an erbium:YAG laser or a catalytic hot-tip catheter suggests that thermal modifications in the arterial surface ultrastructure or thermal denaturation of surface proteins, or both, may be responsible for reduced platelet adherence. These in vitro findings indicate that controlled thermal plaque ablation by catheter-based techniques may elicit endovascular responses that can reduce early thrombus formation during angioplasty procedures.

Laser-assisted angioplasty for arterial occlusion of the lower limb: initial results and follow-up

A flashlamp-pumped pulsed dye laser operating at either 480 or 504 nm, coupled to an integral ball-tipped optical fibre, was used to recanalize occluded lower limb arteries. All channels created by the laser were augmented with balloon dilatation. We have treated 78 limbs in 71 patients; 46 limbs (59 per cent) had rest pain and 22 (48 per cent) of these had tissue loss. The median occlusion length was 18 (range 0.5-58) cm. Technical success was achieved in 58 limbs (74 per cent) with clinical success in 46 (59 per cent). Success rates fell with increasing length of occlusion. Two patients died in the perioperative period. A subgroup of 22 patients with marked discrete arterial calcification had a lower technical success rate than the subgroup without calcification (50 per cent versus 84 per cent, P less than 0.01). Both subgroups displayed a similar pattern of reclosure during follow-up. The cumulative patency rate after technical success was 67 per cent at 6 months and 45 per cent at 12 months. Forty-six (59 per cent) limbs avoided bypass surgery or amputation. Laser-assisted angioplasty may offer an alternative to femoropopliteal bypass, although the former procedure is not as durable.