New approaches to the treatment of vascular lesions

Comparative pilot study evaluating the treatment of leg veins with a long pulse ND:YAG laser and sclerotherapy

BACKGROUND AND OBJECTIVE

To date there have been very few side by side comparison studies of laser versus sclerotherapy in treating small leg veins. This study compares a long pulsed Nd:YAG laser with contact cooling to sclerotherapy for treating small diameter leg veins by evaluating objective and subjective clinical effects.

STUDY DESIGN/MATERIALS AND METHODS

Twenty patients were selected with leg veins ranging from 0.25 to 3 mm at two comparable sites. One site was treated with long pulsed Nd:YAG laser and the other received sotradecol sclerotherapy. The patients followed up at 8 weeks for another possible laser retreatment and 3 months following the last treatment. Photographs were taken pre- and post-operatively and at each follow-up visit and used for objective comparative analysis. The patients also completed a Quality of Life survey.

RESULTS

Improvement was tabulated from the photographic assessment on an improvement scale from 0 (no change)-4 (greater than 75% clearing). The laser treated areas averaged 2.50 and sclerotherapy treated sites averaged 2.30. Patient surveys show 35% preferred laser and 45% choose sclerotherapy.

CONCLUSION

This pilot study demonstrates that the Lyra Long Pulse Nd:YAG laser can yield results similar to sclerotherapy in the treatment of small leg veins.

Analysis of thermal relaxation during laser irradiation of tissue

BACKGROUND AND OBJECTIVE

Thermal relaxation time (tau(r)) is a commonly-used parameter for estimating the time required for heat to conduct away from a directly-heated tissue region. Previous studies have demonstrated that temperature superposition can occur during multiple-pulse irradiation, even if the interpulse time is considerably longer than tau(r). The objectives of this study were (1) to analyze tissue thermal relaxation following laser-induced heating, and (2) to calculate the time required for a laser-induced temperature rise to decrease to near-baseline values.

STUDY DESIGN/MATERIALS AND METHODS

One-dimensional (1-D) analytical and numerical and 2-D numerical models were designed and used for calculations of the time tau(eff) required for the peak temperature (T(peak)) to decrease to values slightly over baseline (DeltaT(base)). Temperature values included T(peak)=65 and 100 degrees C, and DeltaT(base) = 5, 10, and 20 degrees C. To generalize the calculations, a wide range of optical and thermal properties was incorporated into the models. Flattop and gaussian spatial beam profiles were also considered.

RESULTS

2-D model calculations of tau(eff) demonstrated that tau(eff) (2-D) was as much as 40 times longer than tau(r). For a given combination of T(peak) and DeltaT(base), a linear relationship was calculated between tau(eff) (1-D) and tau(r) and was independent of optical and thermal properties. A comparison of 1-D and 2-D models demonstrated that 1-D models generally predicted longer values of tau(eff) than those predicted with a 2-D geometry when the laser spot diameter was equal to or less than the optical penetration depth.

CONCLUSION

Relatively simple calculations can be performed to estimate tau(eff) for known values of tau(r), T(peak) and DeltaT(base). The parameter tau(eff) may be a better estimate than tau(r) of tissue thermal relaxation during multiple-pulse laser irradiation.

Side effects and complications of laser therapy

Laser skin surgery is not without risk and some degree of downtime in most situations. Patient satisfaction is key to the perceived success of the procedure. Therefore, the physician must fully explain all risks, potential complications, and expected morbidity associated with any laser treatment to be performed. Although many side effects can be avoided by use of appropriate intraoperative technique and adequate postoperative management, untoward effects may still occur and must be promptly identified and addressed. An informed patient is an important factor in the healing process and contributes to the success of the procedure.

Laser treatment of congenital and acquired vascular lesions. A review

Several quasi-continuous-wave and pulsed lasers can effectively treat a variety of vascular lesions. The pulsed dye laser and its newer variants were specifically designed to target hemoglobin and, by increasing their wavelengths slightly, have successfully achieved greater depths of penetration. When used in to compliance with the theory of selective photothermolysis, these systems have been shown to be safe and to have a low incidence of adverse sequelae. With the concomitant use of epidermal cooling systems, side-effect profiles have been further reduced. Although great progress has been made in the laser treatment of leg telangiectasias, even the newest laser systems have failed to meet patient expectations. Continuing advances in laser technology, however, will probably lead to enhanced clinical results, decreased side-effect profiles, improved hardware, and reduced costs.

Intense pulsed light source for treatment of facial telangiectasias

OBJECTIVE

The purpose of this clinical study was to evaluate the effectiveness of the first intense pulsed light source (IPL) with dual mode light filtering for treatment of facial telangiectasias, and to evaluate the incidence of adverse including purpura, pigmentation and scars.

MATERIALS AND METHODS

Twenty-four patients with facial telangiectasias were treated between one and four times with a new IPL system. This system differs from previous IPLs by eliminating wavelengths longer than 950 nm, which would otherwise lead to non-specific heating of tissue water. The treatments were performed at one-month intervals. Two months after the last treatment, the clinical effect was evaluated from close-up photographs.

RESULTS

After one to four IPL treatments (mean: 2.54; SD: 0.96) for facial telangiectasias, 79.2% of the patients obtained a more than 50% reduction in number of vessels, and 37.5% obtained between a 75% and 100% reduction. Moderate erythema and oedema were the only adverse effects of the treatment. No purpura was registered and no long-term adverse effects such as scars or pigmentary disturbances occurred.

CONCLUSIONS

An IPL with dual mode filtering is efficient and safe for treatment of facial telangiectasias.

Cryogen spray cooling: Effects of droplet size and spray density on heat removal

BACKGROUND AND OBJECTIVE

Cryogen spray cooling (CSC) is an effective method to reduce or eliminate non-specific injury to the epidermis during laser treatment of various dermatological disorders. In previous CSC investigations, fuel injectors have been used to deliver the cryogen onto the skin surface. The objective of this study was to examine cryogen atomization and heat removal characteristics of various cryogen delivery devices.

STUDY DESIGN/MATERIALS AND METHODS

Various cryogen delivery device types including fuel injectors, atomizers, and a device currently used in clinical settings were investigated. Cryogen mass was measured at the delivery device output orifice. Cryogen droplet size profiling for various cryogen delivery devices was estimated by optically imaging the droplets in flight. Heat removal for various cryogen delivery devices was estimated over a range of spraying distances by temperature measurements in an skin phantom used in conjunction with an inverse heat conduction model.

RESULTS

A substantial range of mass outputs were measured for the cryogen delivery devices while heat removal varied by less than a factor of two. Droplet profiling demonstrated differences in droplet size and spray density.

CONCLUSIONS

Results of this study show that variation in heat removal by different cryogen delivery devices is modest despite the relatively large difference in cryogen mass output and droplet size. A non-linear relationship between heat removal by various devices and droplet size and spray density was observed.