Evaluation of the safety and efficacy of long pulsed Nd: YAG laser in the treatment of vascular lesions in vivo.

Long-pulsed neodymium:yttrium-aluminum-garnet (Nd:YAG) lasers have recently been used for the treatment of vascular lesions refractory to conventional vascular lasers. The aim of this study was to evaluate the clinical efficacy and safety of long-pulsed Nd:YAG laser treatment for vascular disorders. Laser irradiation was performed using two approaches: the 532 nm Nd:YAG laser was used to irradiate the dorsal skin fold in mice and the 1064 nm Nd:YAG laser was used to irradiate the leg of mice without skin incision. The specimens were observed immediately after laser treatment using a laser Doppler perfusion imaging system. Red blood cell (RBC) extravasation and hemorrhage were observed using the hematoxylin and eosin stain. The diameter of blood vessel under 30 μm was disrupted with a laser pulse at a fluence of 12 J/cm² and a wavelength of 532 nm regardless of pulse duration. The veins and arteries of approximately 1 mm in size were ablated with laser pulses at a fluence of 140 J/cm² and above and a wavelength of 1064 nm. Selective photopyrolysis can be achieved with either 532- or 1064 nm Nd:YAG laser pulses in vascular diseases based on the depth and size of the vessel.