The effect of wavelength on endothermal heat-induced thrombosis incidence after endovenous laser ablation

We hypothesized that the incidence of endothermal heat-induced thrombosis (EHIT) depends on the laser wavelength used in endovenous laser ablation (EVLA) of the saphenous veins.

We identified patients undergoing EVLA in our office from 2005 to 2014 with an 810-nm (hemoglobin-specific) or 1470-nm (water-specific) laser. We reviewed the records for age, sex, body mass index, Clinical, Etiologic, Anatomic, and Pathophysiologic (CEAP) class, vein diameter, vein(s) treated, adjunctive phlebectomy, energy delivered, laser pullback times, and EHIT (closure level ≥3) development. The Fisher exact test and Pearson χ(2) test were used to evaluate the association between EHIT and the categoric variables. Logistic regression was used to evaluate the relationship between EHIT and the continuous variables.

There were 1439 veins ablated in 1109 patients (769 female, 340 male). The great saphenous vein (GSV) was treated in 1332, the small saphenous vein (SSV) in 78, and both in 29 (22 procedures on accessory veins were excluded). The CEAP C class for these patients was 1 in 0, 2 in 616, 3 in 522, 4 in 150, 5 in 51, and 6 in 98, and was not recorded in 2. EHIT occurred in 76 cases (5.28%), in 73 after GSV ablation and in three after SSV ablation. The 810-nm laser was used in 1144 procedures, and EHIT developed in 69 patients (6.0%). The 1470-nm laser was used in 295 procedures, with EHIT developing in seven patients (2.4%; P = .0122 by Fisher exact test). The average energy delivered to the EHIT group (3517 ± 1998.1 J) was higher than for the non-EHIT group (2825.1 ± 1491.2 J; P = .0002). The average vein diameter was larger in the EHIT group (9.3 ± 3.8 mm) than in the non-EHIT group (7.2 ± 3.3 mm; P = .0001). EHIT occurred in 59 of 837 cases (6.6%) undergoing simultaneous stab phlebectomy compared with 17 of 525 cases (3.1%) undergoing only EVLA (P = .0049). Statistical analysis confirmed the association between EHIT and CEAP class was significant (P = .0001). No differences were seen for age, body mass index, sex, combined bilateral, and multiple or simultaneous GSV and SSV ablations between the two groups. A multivariate analysis confirmed that CEAP class, vein diameter, adjunctive phlebectomy, and laser wavelength were indeed risk factors for post-EVLA EHIT and that energy delivered and pullback time were not.

Water-specific laser fiber wavelength (1470 nm) reduces the risk of EHIT compared with a hemoglobin-specific wavelength (810 nm). CEAP class, simultaneous phlebectomy, and vein diameter >7.5 mm are associated with increased risk of EHIT after EVLA.