Optimal pulse durations for the treatment of leg telangiectasias with a neodymium YAG laser

Abstract

Background: Leg veins can be effectively treated with lasers. However, the optimal pulse duration for small leg veins has not been established in human studies with a Nd:YAG laser. Objectives: The purpose of this study was to investigate a range of pulse durations to determine an optimal pulse duration for clearance of leg veins. Study Design/Materials and Methods: After mapping and photo documentation of the leg veins to be treated, a variable pulse duration Neodymium:Yttrium Aluminum Garnet (Nd:YAG) laser (3-100 milliseconds) was used in a single test site session. Pulse durations of 3, 20, 40, 60, 80, and 100 milliseconds were used. At the 3-week follow-up, the optimal pulse duration was defined as that pulse duration which resulted in the most complete clearance of vessels with the least side effects. Up to 20 vessels were then treated using the established ''optimal'' pulse duration. Final evaluation was at 16 weeks after the initial visit. Three blinded observers rated the percent of vessels completely cleared based on initial and final photographs. Results: Eighteen patients completed the study. Fluence thresholds for immediate vessel changes varied depending on spot size and vessel diameter, with larger fluences required for smaller spot sizes and smaller vessels. Shorter pulse durations ( 20 milliseconds) were associated with occasional spot sized purpura and spot sized post-inflammatory hyperpigmentation. Longer pulse durations (40-60 milliseconds) achieved superior vessel elimination with less post-inflammatory hyperpigmentation. With a single laser treatment, 71% of the treated vessels cleared. Conclusions: Compared to shorter pulses (<20 milliseconds), longer pulses may provide gentler heating of thevessel and a greater ratio of contraction to thrombosis.

Indocyanine green‐augmented diode laser therapy of telangiectatic leg veins: A randomized controlled proof‐of‐concept trial

“…In practice, the 1.064 nm Nd:YAG laser is widely used for treating telangiectatic leg veins, and pain is also a typical side effect of this laser. Parlette et al 32 evaluated pain caused by Nd:YAG laser treatment of telangiectatic leg veins in 18 patients on a VAS: 0 (absent), 1 (mild), 2 (moderate), 3 (severe). The 6 mm spot was associated with a mean pain score of 2.5, the 3 mm spot with a score of 2.1.…”

Nd:YAG Laser

“…Pulse widths shorter than 20 ms tend to result in purpura and more postinflammatory side effects. Fluences between 100 and 200 J/cm 2 and pulse widths between 20 and 100 ms are thought to keep dermal heating to a minimum while still providing effective results [28,29]. The thermal relaxation time of any target is directly proportional to its diameter.…”

Laser Treatment of Superficial Leg Veins: A Review

“…Very short pulse durations (<20 ms) can cause purpura the size of the laser spot to develop. Leg veins ranging from 0.2 to 0.8 mm in diameter have thermal relaxation times of 20 to 300 ms, 13 so pulse durations of 40 to 60 ms provide optimal treatment parameters of spider leg veins, resulting in clinical elimination of the vessel, histologic vessel contraction, and hyalinized perivascular collagen formation 13 . Postinflammatory hyperpigmentation is the most common adverse effect after laser treatment of leg veins.…”

“…Postinflammatory hyperpigmentation is the most common adverse effect after laser treatment of leg veins. This complication is more common in patients with darker skin types, in patients with significant sunlight exposure, in patients in whom insufficient proximal larger veins (feeder veins) are not treated before treating the distal veins, after use of shorter pulse durations (<20 ms), in patients who develop purpura from the rupture of blood vessels by the laser light or other light source, and in patients with vessels that develop thrombus formation after treatment 13 . The hyperpigmentation usually fades spontaneously over several months.…”

“…Lower fluences (100 to 200 J/cm 2 ) and longer pulse durations are more efficacious for larger vessels (1.5 to 3 mm), whereas higher fluences (250 to 400 J/cm 2 ) and shorter pulse durations are better for treating vessels smaller than 0.5 mm 44 . Longer pulses may provide gentler heating of the vessel and superior vessel elimination of leg veins 0.1 to 1.6 mm in diameter 13 . Longer pulse durations are also associated with less purpura, edema, and hyperpigmentation 7 .…”