Vascular procedures that thermo-coagulate collagen reduce local platelet deposition and thrombus formation: Laser and laser-thermal versus balloon angioplasty

Background and Objective: Exposure of the arterial wall matrix to blood leads to platelet deposition resulting in thrombosis. Because heat alters tissue matrix we proposed that heating reduces platelet deposition. Study Design/Materials and Methods: Sixty arterial homografts (15 dogs) were mounted in an arterio-venous "shunt." Interventions included balloon angioplasty (BA), direct laser (LA), laser-thermal (LTA), and combined LTABA. (111)Indium-labeled platelets were circulated, radioactivity measured, and homografts processed for histology. Results: Radioactivity count (mean SE) at BA sites (13,853 +/- 3,192 cpm/cm(2)) was greater than LA (7,038 +/- 981), LTA (5,294 +/- 1,145), LTABA (6,176 +/- 1,571), and control (1,826 +/- 339), P < 0.05. Electron microscopy showed fewer platelets at LA, LTA, and control than BA sites. BA spread the collagen on the arterial lumen while heat gelled collagen and confined it to the arterial media. Conclusion: Heating the artery and gelling collagen during LA, LTA, or LTABA significantly reduced thrombogenicity. Lasers Surg. Med. 29:455-463, 2001. (C) 2001 Wiley-Liss, Inc.