Histological Changes Occurring After Endoluminal Ablation With Two Diode Lasers (940 and 1319 nm) From Acute Changes to 4 Months

Background: Endovenous laser ablation of the saphenous vein was studied from a histologic analysis to establish changes that occur from time of injury to 4 months when the vein is difficult to visualize by ultrasound. Methods: Twenty-four patients were examined after treatment with either a 1319 nm diode laser (Sciton, Palo Alto, CA) or a 940 nm diode (Dornier, Kennasaw, GA) 12 patients were randomly assigned to the 940 nm group and 12 patients to the 1319 nm group. Histologic evaluations were only done once per patient. All patients had symptomatic saphenous insufficiency with varicosities. All were in CEAP class 3 or 4. Sections of treated veins were submitted for evaluation after staining with hematoxylin-eosin. The evaluations were done acutely, at 1 and 4 months. Ultrasound findings were also evaluated and compared at the same intervals. Results: Acutely, all examined veins revealed loss of intima. In the 1319 nm group numerous vacuoles were present in the subintimal layer. On gross exam at 1 month, both groups showed vein wall thickening, intraluminal thrombus and inflammatory changes. Histologic evaluation showed thrombus was present with many fibroblasts and inflammatory cells. At 4 months, collagen was the predominant histologic finding. However, the changes were less in regards to the injury response with the 1,319 nm group as manifested by less collagen deposition at 4 months. Conclusion: This study demonstrates the cellular sequence that occurs after endovenous ablation. Fibroblast infiltration is a result of the injury response which leads to negative modeling of the thrombus and eventual collagen deposition. Replacement of the thrombus with collagen is necessary for eventual long-term success. Lasers Surg. Med.40:676-679, 2008. (c) 2008 Wiley-Liss, Inc.