| Abstract: | Laser Balloon Angioplasty (LBA) is a technique that may improve the results of balloon angioplasty by thermally sealing arterial dissections and reducing elastic recoil. To define the relationship between laser-exposure duration and the strength of thermal welds made between separated layers of arterial wall, 360 1-cm discs of human postmortem aorta were lased for six different exposure intervals at three different temperature ranges, comparing shear strength of thermal welds in the different groups. Twenty discs were lased to achieve plateau adventitial temperatures of 95 degrees C-104 degrees C (group A), 105 degrees C-114 degrees C (group B), or 115 degrees C-124 degrees C (group C) at each of the exposure periods (5, 10, 15, 20, 25, and 30 sec). A 400-micron fiberoptic coupled to a 1.06 micron continuous wave neodymium:YAG laser was placed perpendicularly 8 mm above the luminal surface of each disc, which had been split midway between the intimal and adventitial surface and reapposed. Mean laser energy ranged 78-378 J delivered in a decremental stepwise fashion to achieve quickly and maintain the target plateau tissue temperature. Mean weld strength increased in relation to both achieved tissue temperature and laser-exposure duration, with at least 10 sec necessary, at temperatures greater than 95 degrees C, for reliable thermal welding. Laser exposure for greater than 20 sec provided no statistical increment in weld strength. In the anticipated clinical performance of LBA, these data suggest that when thermal fusion of disrupted arterial tissues is desired, a laser-exposure duration of 10-20 sec is optimal. |
