The Effect of Laser Wavelength on Endothermal Heat Induced Thrombosis after Endovenous Laser Ablation
William P Shutze, Sr.1, Katherine Kane1, Tammy Fisher1, Yayha Daoud2, Grace Lassiter3, Richard Lueking3, Elizabeth Nguyen3, William Shutze, Jr.1, Greg Pearl1, Bert Smith1
1Baylor University Medical Center, Dallas, TX;2Baylor Scott and White Health, Dallas, TX;3Texas A&M Health Science Center College of Medicine, Bryan, TX
Objectives: Endothermal heat induced thrombosis (EHIT) of the common femoral vein or popliteal vein can occur after Endovenous laser ablation (EVLA) of the saphenous veins. We have previously reported an incidence of 5.1% and identified that a vein diameter of 7.5 mm or greater increased the risk of EHIT after EVLA using an 810 nm wavelength laser. The impact of laser wavelength on EHIT has not been previously evaluated and we hypothesized that the incidence of EHIT would depend on the laser wavelength.
Methods: We identified patients having EVLA in our office from 2005-2014 with either a 810 nm (hemoglobin specific) or 1470 nm (water specific) laser. We reviewed the records for age, gender, BMI, CEAP class, vein(s) treated, adjunctive phlebectomy, energy delivered and EHIT (level 3 or higher) development, treatment and course. Fisher’s Exact test and Pearson’s Chi square were used to evaluate the association between DVT and the categorical variables. Logistic regression was used to evaluate the relationship between DVT and the continuous variables.
Results: There were 1456 veins ablated in 1118 patients (775 female, 343 male). The greater saphenous vein (GSV) was treated in 1337, the small saphenous vein (SSV) in 77 and both were treated in 20 (twenty two procedures on accessory veins were excluded). The CEAP class for these patients was 1(0), 2(618), 3(521), 4(148), 5(50), 6(95) and not recorded in 2. EHIT occurred in 71 cases (4.95%), 68 after GSV ablation and 3 after SSV ablation. The 810 nm laser was used in 1142 and 64 (5.6%) developed EHIT. The 1470 nm laser was used in 292 with 7 (2.4%) developing EHIT (Fisher’s Exact test; p = .0229).
The average energy delivered to the EHIT group (3475+ 1941 joules) was higher than for the non-EHIT group (2866+1475 joules) (p=0012). The average vein diameter was higher in the EHIT group (9.3+3.9 mm) than in the non-EHIT group (7.2+3.2 mm) (p=0.0001). EHIT occurred in 55 of 836 patients (6.17%) having simultaneous stab phlebectomy compared to 16 of 527 (2.95%) of patients having only EVLA (p = 0.0057). Statistical analysis confirmed there is significant association between DVT and CEAP class (p = 0.0001). No differences were seen for age, BMI, gender, anticoagulation use, combined bilateral procedures or simultaneous GSV and SSV ablations between the two groups.
The EHIT in the femoral vein were of level 3 (22), 4 (18), 5(17) and 6 (14) and treatment for the EHIT consisted of observation, anticoagulation or antiplatelet therapy. Duration of therapy was usually brief. No pulmonary emboli occurred in any of these patients and EHIT resolved completely in all.
Conclusion: This study shows that a water specific laser fiber wavelength (1470 nm) reduces the risk of EHIT compared to a hemoglobin specific wavelength (810 nm). It also demonstrates that CEAP class, increased energy delivery, simultaneous phlebectomy and increased vein diameter are associated with increased risk of EHIT after EVLA.
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