Plaque modification with tetracycline: enhanced tissue ablation with the excimer laser

Tetracycline has been shown to collect selectively in atherosclerotic plaque and is a known photosensitizing agent. To determine if tetracycline enhances the photoablative effects of the ultraviolet xenon-fluorine excimer laser, the authors exposed four cadaveric aortic samples to tetracycline and four to only normal saline. Ninety-three sites in the samples were subjected to laser energy and analyzed with light microscopy for crater depth and width and for degree of thermal injury. Forty-three of the sites were histologically normal, and 50 were atherosclerotic. Crater depth did not differ significantly in atherosclerotic and normal sites not exposed to tetracycline. Atherosclerotic sites exposed to tetracycline showed significantly deeper craters compared with those in normal, exposed sites. The effects of tetracycline exposure and histologic characteristics (normal vs atherosclerotic) on crater width and thermal injury were independent and additive. When the excimer laser is used for treatment, tetracycline can definitely enhance atherosclerotic plaque ablation.