Introduction: Radio waves and lasers can be used as heat sources during endovenous thermal ablation (EVTA) for saphenous vein insufficiency. A morphological comparison of veins that had been treated with EVTA was performed between those treated with an endovenous closure system (a radiofrequency [RF] system) and those treated with a Radial 2Ring fiber connected to a 1470-nm laser generator (2R).

Methods: The experiment was conducted in a system that reproduces the physiological conditions found in the saphenous veins during EVTA. The 2R experiment was performed at two different power levels, 60 J/cm (2R-60) and 90 J/cm (2R-90). The heated vessels were morphologically examined in detail, and the detected morphological changes were classified into three groups: low-temperature changes (LTC), mid-temperature changes (MTC), and high-temperature changes (HTC). The thickness of the layers exhibiting each type of change was measured.

Results: In the 2R groups, HTC, MTC, and LTC were observed from the superficial to deep layers. In the 2R-60 group, the layers exhibiting LTC, MTC, and HTC were 17 ± 3.2, 42 ± 10.5, and 190 ± 14.6 µm thick, respectively. In the 2R-90 group, these layers were 14 ± 4.0, 105 ± 64.2, and 363 ± 71.3 µm thick, respectively. In the RF group, only LTC were observed (thickness: 251 ± 72.6 µm).

Conclusions: The RF device was able to heat the target vessels more efficiently than the laser device.