Percutaneous recanalization of arteries: Status and prospects of laser angioplasty with modified fibre tips

Abstract

Percutaneous balloon dilatation of arterial stenoses is a firmly established non-surgical treatment of ischaemic disease. The number of percutaneous transluminal coronary angioplasties performed per year in the USA approaches the number of coronary artery bypass graft operations. A great number of novel percutaneous recanalization schemes address the major problems of balloon angioplasty: failure to cross the stenosis (occlusion), failure to dilate effectively (15–20%), acute complications (5%) and re-stenosis within six months (30–40%). Laser energy can effectively evaporate atheromatous plaque, but delivery by an unmodified bare fibre creates only a small channel and carries a high risk of vessel-wall perforation in the coronary arteries. It appears impossible to maintain an axial position in small, tortuous and moving arteries with multiple side-branches. Coronary lesions are anatomically and structurally heterogeneous. Reduction of the perforation risk is being approached by four strategies: (a) optimization of the power source; (b) enhancement of laser-light absorption by plaque relative to artery wall; (c) improvement of plaque recognition; and (d) modification of the delivery system, which is discussed in detail. Recanalization of occluded femoropopliteal arteries with the 2.0-mm metal laser probe has proved to be safe and effective in more than 100 patients. The 2.2-mm rounded sapphire contact probe has been used with success in the peripheral arteries of over 30 patients. The recanalization mechanism of both probes is not yet fully understood. Closed-chest attempts at recanalization of coronary arteries by the 1.7-mm metal laser probe have been reported in 13 patients, with success in the majority. There were no complications requiring emergency surgery. The possible occurrence of embolism or spasm in three cases warrants a cautious approach to application of the metal laser probe in the coronary catheterization room. The primary benefit of laser recanalization with modified fibre tips is the possible transformation of a candidate for surgery into a candidate for balloon angioplasty. It remains to be established whether prior laser debulking of the atheroma will reduce the incidence of acute complications of balloon dilatation and will reduce restenosis in the subsequent year. In the past two years an avalanche of laser and non-laser recanalization schemes have been developed. In peripheral arteries, early results of most methods have shown an acceptably low incidence of acute perforations or other complications. The human arterial wall can take a heavy beating, both mechanically and thermally. In the next decade, catheter intervention techniques will progressively contribute to the treatment of peripheral and coronary artery disease.