Next generation catheters for excimer laser coronary angioplasty.

Abstract

In response to the need for maximising debulking in complex lesions, three new excimer laser coronary angioplasty catheter designs have been introduced. The eccentric laser catheter features a fibreoptic bundle disposed opposite the guide-wire lumen at the catheter tip and a torque mechanism that allows the user to rotate the fibre bundle toward the lesion mass. Residual lumens 50% larger than the catheter tip diameter have been obtained when multiple passes were made, with each pass performed using a different tip rotation. A recent case series utilising this catheter in restenosed stents resulted in larger lumens and lower 6-month restenosis rates. The optimal spaced (OS) laser catheter features a fibre bundle placed concentrically around the guide-wire lumen. The 61 microm diameter core fibres are spaced at a nominal centre-to-centre distance of 90 microm, resulting in a 40% increase in ablative area as compared to previous concentric catheter designs. In vitro testing and clinical evaluation demonstrated OS catheters routinely achieve an ablated area > or =90% of the catheter tip size. The 0.9 mm catheter features a high-density fibre pack composed of 65 fibres. Peripheral dead space has been minimised to maximise penetration of calcified plaque. When combined with laser parameters of up to 80 mJ/mm2, and 80 Hz pulse repetition rate, the catheter demonstrated improved hard tissue and calcified tissue penetration in vitro. Clinical evaluation in Canada revealed a 94% lesion recanalisation rate in high-grade stenoses with angiographic evidence of calcification, chronic total occlusions, and lesions which have failed balloon angioplasty.