Fiberoptic Delivery and Vaporization Using a Long Pulse Excimer Laser

Abstract

We studied the ablative effect of a long-pulse excimer laser (XeCl, 308nm, pulse-width; 70ns, pulse-energy: 42mJ/pulse) on porcine myocardium, and compared that with that of a short-pulse one (308nm, 2Ons, 12mJ/pulse) which we had used before. In the second experiment, after coupling this long-pulse excimer laser light into a quartz fiber (400,μm core-diamter), we measured the distal fiber-end laser energy and examined the ablative effect of the laser transmitted through the fiber.
In result, the cuts produced with the long-pulse laser clearly defined such sharp edges as with the short-pulse one. With the both long-and short-pulse laser, the depth of cuts increased with the number of pulses and the pulse repetition rate. The width of discoloration around the cut margin also increased with the number of pulses and the pulse repetition rate. However, as a whole, the width with the long-pulse was broad er than that with the short-pulse, which showed the thermal injury with the long-pulse was a little more than with the short-pulse. In the second experiment about the fiber transmission, the distal fiber-end power of 16mJ/pulse (128mJ/mm²) with the long-pulse was obtained successfully, compared with 4mJ/pulse with the short-pulse. Besides, the ablative effects of the laser transmitted via the fiber were little different between the long-and short-pulse, though the thermal injury was somewhat more with the long-pulse.
The result suggested the ablative effect of the long-pulse excimer laser were little different with the shoht-pulse, except a slight increase of thermal injury with the long-pulse, and that the elongation of pulse width could make it easy to couple the laser light into the fiber. Therefore, it was expected we would be able to employ this long-pulse excimer laser device to clinical laser angioplasty in no distant future.