Homogeneous light distribution to reduce vessel trauma during excimer laser angioplasty.

Excimer laser coronary angioplasty (ELCA) is associated with vascular damage, caused by rapidly expanding water vapour bubbles and accumulation of insoluble gas. The size of the rapidly expanding bubbles and the volume of gas can be reduced by decreasing the laser pulse energy density. However, using current multifibre catheters, penetration through porcine aortic tissue was found to be impossible at energy densities < or = 45 mJ/mm2. By contrast, by employing a 660 microns bare fibre it was observed that efficient tissue crossing was possible at 12 mJ/mm2, with considerable reduction of the rapidly expanding bubble volume and insoluble gas production. We attribute this efficient tissue penetration at low energy densities to the absence of 'dead space' in the homogeneous light distribution (HLD) at the fibre tip. Accordingly we hypothesize the ELCA performed at lower energy densities may result in less mechanical trauma to the vessel wall when compared with ELCA using current multifibre catheters.