A multicenter clinical randomized controlled trial, comparing of three different regimens of endovenous laser ablation with equal linear endovenous energy density in patients with insufficiency of the great saphenous vein (GSV). The linear endovenous energy density (LEED) is the main value for standardization EVLA. From many studies, it is known the optimum value of the LEED. However, the same LEED may be obtained by varying the ratio between the laser power and the fiber pullback speed. Power decrease can allow to reduce the incidence of adverse effects of endovenous laser ablation, but keep high efficiency.

Inclusion Criteria:

Patients over 18 years old Insufficiency of the GSV measured with ultrasound imaging, reflux > 0.5 sec No prior treatment of the insufficient GSV Informed consent

Exclusion Criteria:

Acute deep or superficial vein thrombosis Agenesis of deep vein system Vascular malformation or syndrome Post-thrombotic syndrome, occlusive type Pregnancy Phlebectomy on the thigh Immobility Allergy to lidocaine Arterial insufficiency

Data collection will take place at the Russian Registry of Treatment of Chronic Venous Diseases (RRT CVD). Access to the data will be available after completion of the study. To access the data will need to send a request to RRT CVD administrator. Register in Russian. Registry now listed in the database ClinicalTrials.gov, ID NCT03035747 (see references)