Vessel hyalinization phenomenon in the laser treatment of tuberous hemangiomas and port wine stains

The 800-nm diode laser in the treatment of leg veins: assessment at 6 months

BACKGROUND

The efficacy of the 800-nm diode laser system in clearing leg veins was analyzed subjectively and objectively in a variety of leg veins.

METHODS

A total of 10 women (age 25-55 years, skin types II-IV) with a variety of leg vein types were treated with an 800-nm diode laser. A sequence of pulses (5-8 stacked pulses, pulse duration 50 milliseconds, delay 50 milliseconds) was applied on a 3-mm spot (210-336 J/cm2 fluence, depending on vessel size). Treatment on the same vein was performed at intervals of 2 months until complete clearance was achieved (maximum: 3 treatments). The results were assessed at 6 months from the last treatment. Patients evaluated their subjective improvement by means of a questionnaire to elicit the satisfaction index. In an independent objective assessment, the clearance index was based on the pretreatment and posttreatment clinical photography, also analyzed by a computer program.

RESULTS

All patients completed the trial with mild but transient side effects. The patient 6-month assessments for very good, good, fair, poor, and worse were 1, 5, 3, 1, and 0, respectively. For the clinician-assessed clearance index, the numbers for the same grades were 2, 6, 2, 0, and 0, and for the computer assessment they were 1, 6, 2, 1, and 0. No patient scored worse in any assessment. The overall satisfaction index and clinician and computer clearance indexes were 60%, 80%, and 70%, respectively.

LIMITATIONS

No control group could be obtained in this study.

CONCLUSIONS

The 800-nm diode laser as used in the study may well offer an effective treatment method for leg veins that is comparatively pain and side-effect free. Best results were obtained in vessels of 3 to 4 mm in diameter located on the thigh, and in patients with phototype III skin. No correlation was seen between results and patient age.

Possible mechanisms for an irregular vessel coagulation when long laser pulses are used in the treatment of port-wine stains

The laser treatment of port-wine stains (PWS) has as a main aim the irreversible damage of ectatic vessels. Blood content of the subcutaneous venous plexus in PWS can be increased by a factor of seven or more, compared to that of the normal skin. The venous blood velocity ranges from 0.1-1 mm/s in capillaries to approximately 22 mm/s in larger vessels of about 300 microns in diameter. A PWS, selected for study, was irradiated with a multiline argon laser 488/515 nm wavelength, 1.5 W power, 200 ms pulse duration, 0.5 mm beam diameter and repetition frequency up to 5 Hz. Laser shots were placed adjacently in an area of 1 cm2. Using these parameters, in the case of dilated PWS vessels with an optical penetration depth and thermal diffusion length less than the diameter of the vessel, together with a transit time of blood across the irradiated spot less than the pulse duration, and estimating that during a pulsed laser emission of 200 ms, the blood has travelled a distance of 3-4 mm, there is a strong indication that hemodynamics during irradiation may influence the pattern of coagulation and agglutination. Thrombosis should occur in the case of small vessels and, in larger vessels, the coagulated blood will only partly fill the lumen. The structure developed in the vessel interior may also change continuously with time, as the coagulated material is progressively replaced by fibrotic tissue and the irregular agglutination pattern may be due to inhomogeneity in the absorbed optical energy.