PERPHERAL VASCULAR DISEASE Angiographic and histologic consequences of laser thermal angioplasty : comparison with balloon angioplasty TIMOTHY

The angiographic and histologic consequences of laser thermal angioplasty were examined and compared with those of conventional balloon angioplasty in an atherosclerotic rabbit iliac artery preparation immediately and 4 weeks after the procedure. Nineteen vessels in 13 rabbits underwent either laser thermal or balloon angioplasty in random order. Laser thermal angioplasty was performed in a total of nine vessels with either a 1.5 or 2.0 mm laser-heated metallic-capped fiber by delivery of 6 or 8 W, respectively, of argon laser energy for 5 sec duration during continuous advancement through the stenosis. Balloon angioplasty was performed in a total of 10 stenotic lesions with a 2.5 mm balloon catheter. The immediate enlargement of the angiographic luminal diameters was similar for both procedures: from 1.0 + 0.2 to 1.9 0.2 mm for laser thermal angioplasty vs 1.0 + 0.1 to 2.0 + 0.2 mm for balloon angioplasty. However, 4 weeks later the vessels treated with laser thermal angioplasty had less restenosis, defined as a 20% or greater reduction in luminal diameter (two of nine vessels [22%] vs 10 of 10 vessels [100%]; p < .001), and a significantly larger mean luminal diameter (1.6 + 0.5 vs 1.0 + 0.4 mm) than those treated with conventional balloon angioplasty (p < .02). Histologic examination 4 weeks after the procedure revealed less fibrocellular proliferation after laser thermal angioplasty, whereas those vessels treated with balloon angioplasty demonstrated evidence of prior fracture and dissection of the vessel wall with more of a fibrocellular proliferative response. Morphometric analysis of these histologic cross-sections confirmed a significantly larger lumen after laser thermal angioplasty compared with balloon angioplasty (1.24 0.62 vs 0.64 + 0.45 mm2; p < .05). In summary, in rabbit iliac artery stenoses, laser thermal angioplasty was associated with less restenosis and produced a significantly larger mean luminal diameter and mean luminal area than conventional balloon angioplasty. Differences in the pathophysiologic mechanisms of angioplasty with these two techniques may be responsible for this observation and may have clinical relevance. Circulation 75, No. 6, 1281-1286, 1987. LASER ANGIOPLASTY has the potential to serve as an adjunct or alternative to conventional balloon angioplasty, which has shown impressive clinical results but is limited by a lower success rate (54%) in totally occluded coronary vessels1, 2 and is complicated by an early restenosis rate that approaches 30% to 40%. However, the cardiovascular use of lasers has been limited by a reported 20% to 66% incidence of vessel From the Evans Memorial Department of Clinical Research and the Department of Medicine, University Hospital, Boston University Medical Center and Mallory Institute of Pathology, Boston. Supported by grant 13-503-834 from the American Heart Association, Massachusetts Affiliate. Address for correspondence: Timothy A. Sanborn, M.D., Department of Cardiology, University Hospital, 75 Newton St., Boston, MA 02118. Received May 27, 1986; revision accepted March 6, 1987. perforation in experimental5 6 and clinical studies7 8 and poor long-term patency in a preliminary clinical trial.7 If this technique is to achieve widespread clinical use, both the shortand long-term consequences of the procedure need to be assessed and compared with results of currently available balloon angioplasty to determine the precise role of this new therapy in relation to existing techniques. In a prior study,5 improved safety and efficacy of laser thermal angioplasty was demonstrated in an atherosclerotic rabbit iliac artery preparation with a metallic-capped fiber (Trimedyne Inc., Santa Ana, CA) in which argon laser energy is converted to heat in the enclosed cap at the end of the fiberoptic fiber.9 In this previous study, a lower incidence of perforation and greater angiographic success were evident when Vol. 75, No. 6, June 1987 1281 by gest on N ovem er 6, 2017 http://ciajournals.org/ D ow nladed from