Factors affecting optimal linear endovenous energy density for endovenous laser ablation in incompetent lower limb truncal veins – A review of the clinical evidence

Abstract

Objectives The objective is to identify the factors that affect the optimal linear endovenous energy density (LEED) to ablate incompetent truncal veins. Methods We performed a literature review of clinical studies, which reported truncal vein ablation rates and LEED. A PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) flow diagram documents the search strategy. We analysed 13 clinical papers which fulfilled the criteria to be able to compare results of great saphenous vein occlusion as defined by venous duplex ultrasound, with the LEED used in the treatment. Results Evidence suggests that the optimal LEED for endovenous laser ablation of the great saphenous vein is >80 J/cm and <100 J/cm in terms of optimal closure rates with minimal side-effects and complications. Longer wavelengths targeting water might have a lower optimal LEED. A LEED <60 J/cm has reduced efficacy regardless of wavelength. The optimal LEED may vary with vein diameter and may be reduced by using specially shaped fibre tips. Laser delivery technique and type as well as the duration time of energy delivery appear to play a role in determining LEED. Conclusion The optimal LEED to ablate an incompetent great saphenous vein appears to be >80 J/cm and <95 J/cm based on current evidence for shorter wavelength lasers. There is evidence that longer wavelength lasers may be effective at LEEDs of <85 J/cm.

Effect of spatial light distribution on the thermal response of vascular tissue

“…Furthermore, the emission angles around ± 45° from the radial fiber yielded a long irradiation pathway for the light to reach the vein wall, which could be more absorbed by saline during the light transmission. Nevertheless, the radial fiber has been well accepted for clinical EVLA due to high success rates of varicose vein treatment [11,18]. Therefore, further preclinical or clinical evaluations on the two fibers are still required for the potential clinical translation of the cylindrical irradiation.…”

“…A number of varicose vein treatments have been developed, such as open venous surgery, sclerotherapy drugs, steam bubble generation, varicose radiofrequency closure, endovenous laser ablation (EVLA), and high intensity focused ultrasound [3,[7][8][9]. Among the treatments, the EVLA procedure was highly recommended by the National Institute for Health and Clinical Excellence as an effective minimally invasive method for truncal vein reflux causing varicose veins due to a high success rate of > 90% [10,11].…”

“…In spite of effective treatment, EVLA is often associated with excessive heating, leading to pain and burning that increase the risk of dermatitis [4,12]. To reduce these complications, various improvements have been suggested such as various wavelengths (810 to 2000 nm) [13,14] and optical delivery devices (flat, tulip-shaped, lens-capped, and radial fiber) that are already in use for clinical applications [11,15]. Strong light absorption by water both in the blood and the vein wall enables the longer wavelengths (1320, 1470, 1885, and 1940 nm) to attain more consistent and marked heating to the vein, eventually reducing postoperative pain [16].…”

Bare Tip versus Radial Endovenous Laser Ablation for the Treatment of Primary Varicose Veins

“…The mean LEED used in this study was 79 and 78.3 J/cm for the bare tip and radial respectively. This <85 J/cm level was suggested to be effective when used with WSLW, theoretically producing a maximum effect at the vein wall, while reducing the chance of surrounding tissue injury (29) . When the bare tip and the radial groups were compared, no statistical difference was found regarding the studied parameters.…”

Endovenous Laser Ablation of the Great Saphenous Vein with Large Sapheno-Femoral Junction

“…Линейная плотность энергии в расширенной зоне составляла от 101,3 до 172 Дж/см. Данные настройки были выбраны эмпирически, учитывая большой разброс рекомендованных параметров для ЭВЛО в клинических рекомендациях и доступной литературе [6][7][8], а также в связи с отсутствием работ с удовлетворительной выборкой, посвященных облитерации вен такого диаметра.…”