The purpose of these experiments was to simulate thrombus formation during endovenous laser closure by measuring coagulum formation of in vitro laser exposures in porcine blood and investigate the role of procedures and equipment in thrombus formation.

Continuous wave 810, 940, 980, 1310 and 1470 nm lasers and microsecond pulsed wave 1064 nm Nd:YAG (neodymium-doped yttrium aluminium garnet), 1320 nm Nd:YAG and 2100 nm THC:YAG (thulium holmium chromium-doped yttrium aluminium garnet) lasers were tested with standard fibres with diameters of 365, 550 and 600 μm as well as two prototype modified tip fibres.

The results show that pulsed lasers with high-peak power densities form less coagulum. Fibre specifications were found not to influence coagulum formation, and prototype modified tip fibres designed to prevent contact between the fibre tip and the vein wall did not eliminate coagulum formation.

Microsecond-pulsed wave lasers with high-peak power densities may be a better choice to minimize soft thrombus formation during endovenous laser ablation treatments.