New approaches to the laser treatment of vascular lesions

Vascular damage mechanism and parameter optimization under alexandrite laser irradiation: a theoretical study

The 755-nm Alexandrite Laser has a good clinical effect in treating resistant port wine stain, without causing thermal damage of normal tissue and side effects such as purpura. However, little is known about the mechanism of vascular damage induced by 755-nm laser irradiation, which restricts the optimization of laser parameters. In this work, the thermal damage model and the pressure damage model were used to study the damage mechanism of 755-nm laser irradiation on vessels, and the incident energy density and pulse width required for vascular damage were determined according to the damage mode. Under the irradiation of 755-nm laser, the vascular injury pattern was the co-occurrence of vessel rupture and vessel constriction, and the energy density required for the treatment of vessels with a diameter of 200 μm to reach the damage threshold was the lowest.

Analysis of the Curative Effect of Alexandrite Laser in the Treatment of Venous Lake of Lips

BACKGROUND AND OBJECTIVES

Laser is being widely used in clinical treatment nowadays, including 755 nm Alexandrite laser [1,2]. This study was conducted to examine the clinical outcome of long-pulse 755 nm Alexandrite laser in the treatment of venous lake of the lip.

STUDY DESIGN/MATERIALS AND METHODS

Forty-one patients (2015-2019) were reviewed. The clinical outcomes were assessed 1 month after the treatment. The efficacy of the treatment was classified into four categories: basic recovery (most optimal outcome), effective, improvement, and ineffective (least favorable outcome). Adverse reactions were also recorded.

RESULTS

Thirty-three (80.49%) patients achieved basic recovery and 8 (19.51%) were effective; 29 (70.73%) recovered after receiving one treatment, 3 (7.32%) recovered after receiving two treatments, and 1 (2.44%) recovered after three treatments.

CONCLUSION

Long-pulse 755 nm Alexandrite laser is an effective treatment for the venous lake of the lip. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Safety and efficacy of dual-wavelength laser (1064 + 595 nm) for treatment of non-treated port-wine stains

BACKGROUND

Patients with port-wine stain (PWS) suffer physically and psychologically because of the high incidence (0.3%-0.5%) of the disease. Pulsed-dye laser (PDL) at 595 nm is the gold standard of the treatment for PWS. Nevertheless, clinicians intend to determine whether the dual-wavelength laser (DWL; 595-nm PDL + 1064-nm Nd:YAG) is an adequate choice in the treatment of non-treated PWS. This study is the first prospective within-patient controlled research seeking to investigate the safety and efficacy of DWL for the treatment of non-treated PWS.

METHODS

A total of 61 patients with non-treated flat facial PWS, who were treated using the Cynergy laser system in our clinic, were included in this study. Each PWS lesion was divided into two adjacent test treatment sites of similar size and colour. The two sites were randomly assigned to PDL or DWL treatment in a blinded manner of participants. In each case, two sets of treatment parameters were used: (i) 595-nm PDL and (ii) 595-nm PDL + 1064-nm Nd:YAG. Both had a 10 mm spot size, an epidermal cooling system and 1-s interpulse interval between two pulses. Clinical efficacy and safety outcomes were evaluated by visual assessment 2 months after treatment.

RESULTS

Comparison by visual evaluation suggests that the responses of non-treated PWS to treatment by PDL and DWL were not significantly different. Moreover, three patients developed scarring after DWL treatment.

CONCLUSION

Compared with PDL, DWL exhibits a higher risk of potential scarring and has no advantage in efficacy of treating non-treated PWS.

A comparison of microvascular responses to visible and near-infrared lasers

BACKGROUND AND OBJECTIVE

Pulsed dye laser (PDL) is a commonly used treatment for Port Wine Stain birthmarks (PWS). However, deeper components of PWS are often resistant to PDL. Deeper penetrating lasers, including the long pulsed Neodymium:Yttrium Aluminum Garnet (Nd:YAG) laser have been used, but carry greater risk. This study evaluates the distinct blood vessel thermal responses to visible (595 nm) and near infrared (1,064 nm) lasers using animal and numerical models.

STUDY DESIGN/MATERIALS AND METHODS

Blood vessels in the rodent dorsal skin chamber (DSC) were irradiated by a 595 nm PDL and a long-pulsed 1,064 nm Nd:YAG laser. Laser-induced immediate and 1-hour post-structural and functional changes in the vessels were documented. Numerical simulations were conducted using a 1,000 µm depth SD mouse skin fold to simulate experimental conditions.

RESULTS

PDL irradiation produced immediate blood vessel hemorrhage. Modeling indicated this occurs due to preferential heating of the superior parts of large blood vessels. Nd:YAG irradiation resulted in blood vessel constriction; modeling indicated more uniform heating of vessel walls.

CONCLUSION

PDL and Nd:YAG lasers result in distinct tissue responses. This supports different observable clinical treatment end points when using these devices. Vessel constriction associated with the Nd:YAG may be more difficult to observe and is one reason this device may carry greater risk.

Laser leg vein treatment: a brief overview

Laser treatment of leg veins has been associated with a number of disadvantages, but the introduction of new devices has increased the role of lasers in the treatment of leg veins. This paper reviews the role of laser devices applied from the surface in the treatment of reticular and spider veins. Success is determined by the proper selection of wavelength, fluence, pulse duration, spot size, and number and frequency of treatments.

Treatment of pulsed dye laser-resistant port wine stain birthmarks

The concept of selective photothermolysis with the 577-/585-nm pulsed dye laser (PDL) revolutionized treatment of relatively common port wine stain (PWS) birthmarks. The majority of PWS can be significantly lightened with the PDL. However, few PWS are lightened completely with PDL and up to 20% hardly lighten at all. PDL-resistant PWS exist in any large cutaneous laser practice and constitute a difficult management problem. This article discusses the proposed cause, and currently available and emerging options for PDL-resistant PWS. These include higher power, longer wavelength, variable pulse width lasers with selective epidermal cooling such as 595-nm PDL, 755-nm alexandrite, 810-nm diode, 1064-nm neodymium:yttrium-aluminum-garnet, and intense pulse light systems. Other promising modalities include topical and systemic photodynamic therapy, electrical optical synergy technology, pulse stacking of similar or differing wavelengths, use of optical clearing agents in conjunction with laser, and erbium laser epidermal stripping before laser treatment.

Mathematical modeling of selective photothermolysis to aid the treatment of vascular malformations and hemangioma with pulsed dye laser

Pulsed dye lasers (PDL) are the standard of care in the treatment of cutaneous vascular disorders such as the port-wine strains or hemangiomas of infancy. Nonetheless, there is still uncertainty regarding the specific laser parameters that are likely to yield optimal clinical outcomes. Using mathematical modeling, we explain and associate clinical outcomes with laser wavelength, radiant exposure, and pulse time and shape. The model's prediction that a continuous PDL pulse of 0.45 ms with a radiant exposure of 6 J/cm(2) is equivalent to delivering a 1.5-ms pulse consisting of three pulses with a radiant exposure of 12 J/cm(2) is in agreement with clinical studies. The model also suggests that for vascular malformations involving vessel diameters in the range of 150-500 microm, one should use a PDL at a wavelength of 595 nm with a radiant exposure of at least 12 J/cm(2) and pulse time of 1.5 ms, delivered in three pulses. Whereas it is calculated that malformations with vessels smaller than 50 microm will not respond to PDL in any clinical setting, an excellent response to PDL treatment at either a 585- or 595-nm wavelength can be expected for malformations with vessel diameters of 50-150 microm. Epidermal cooling is highly recommended for all settings to minimize pain and the risk of side effects. Finally, the model is used to generate a reference table that suggests specific PDL parameters for the treatment of various malformations and hemangiomas. The table cannot replace a clinician's experience with respect to which and how parameters should be changed, but provides a defined window of parameters that should be tried to improve clinical response.

Treatment of linear and spider telangiectasia with an intense pulsed light source

BACKGROUND

The flashlamp-pumped pulsed dye laser (585 and 577 nm) has proved to be an effective and safe treatment option in the therapy of linear and spider facial telangiectasia. Nevertheless, the postoperative purpura, which most patients see as cosmetically disfiguring, has always been a matter of concern.

AIMS

To test the effectiveness and safety of an intense pulsed light source (IPLS), which emits non-coherent light adjustable within the 515-1200 nm range, in the treatment of linear and spider facial telangiectasia.

PATIENTS & METHODS

One hundred and forty patients with linear and stellate facial telangiectasia were treated with an IPLS.

RESULTS

In 94 (67.1%) the results were considered excellent (clearance of 80-100%), 43 (30.7%) showed good results (clearance of 40-80%) and in 3 patients (2.1%) the results were poor (clearance < 40%). Post-treatment side effects were minimal and well tolerated. There were no instances of scarring or other permanent side effects. Owing to the large spot size, a large area could be treated within one session. No anaesthesia was required.

CONCLUSION

IPLS is a highly effective and comparably safe therapeutic alternative to the pulsed dye laser in the treatment of facial telangiectasia. The rate of cosmetically relevant side effects is considerably smaller, patient compliance is excellent and the method can easily be applied in an outpatient setting.

System for the automated photothermal treatment of cutaneous vascular lesions

It is well known that the use of tightly focused continuous wave lasers can be an effective treatment of common telangiactasia. In general, the technique requires the skills of a highly dexterous surgeon using the aid of optical magnification. Due to the nature of this approach, it has proven to be largely impractical. To overcome this, we have developed an automated system that alleviates the strain on the user associated with the manual tracing method. The device makes use of high contrast illumination, simple monochromatic imaging, and machine vision to determine the location of blood vessels in the area of interest. The vessel coordinates are then used as input to a two-dimensional laser scanner via a near real-time feedback loop to target, track, and treat. Such mechanization should result in increased overall treatment success, and decreased patient morbidity. Additionally, this approach enables the use of laser systems that are considerably smaller than those currently used, and consequently the potential for significant cost savings. Here we present an overview of a proof-of-principle system, and results using examples involving in vivo imaging of human skin.

The depth measuring videomicroscope (DMV): A non-invasive tool for the assessment of capillary vascular malformations

BACKGROUND AND OBJECTIVES

The response of capillary vascular malformations (CVMs) to laser treatment is believed to be due to the pattern of capillary ectasia, the depth, diameter, and flow through these capillaries and the amount of competing chromophores within the skin. Videomicroscopy has successfully been used to determine CVM capillary pattern and diameter of vessels. The depth measuring videomicroscope (DMV) allows the depth of capillaries to be measured also. The aim of this study is to examine how capillary depths within a CVM are affected by dye laser treatment using DMV.

STUDY DESIGN/MATERIALS AND METHODS

Thirteen previously untreated patients were examined in a temperature-controlled room. A DMV examination was carried out prior to and 6 weeks following a treatment with pulsed dye laser. A further cohort of 11 resistant CVM patients, who had all received over five treatments, was also examined for comparison.

RESULTS

Using a Wilcoxon Signed rank test, the results showed that the remaining vessels within the CVM as measured using DMV were more deeply located and smaller (P < 0.01 and P < 0.02 respectively), following the laser treatment. Also in the resistant patients the vessels were again more deeply placed and smaller.

CONCLUSIONS

The hypothesis that smaller and more deeply placed CVM vessels respond poorest to laser treatment is supported by these findings. Moreover, the DMV provides a simple non-invasive technique for demonstrating this.

Algorithm for using a long-pulsed Nd:YAG laser in the treatment of deep cutaneous vascular lesions

BACKGROUND

Conventional therapies for deep cutaneous vascular anomalies have demonstrated poor efficacy and many side effects. New laser systems offer greater potential to treat these difficult lesions, but the lack of specific treatment guidelines has restricted consistent success.

OBJECTIVE

To establish a rational, user-friendly algorithm that incorporates basic components of deep vascular lesions to define the correct laser settings required for safe, effective, and reproducible treatment.

METHODS

Within 18 months, 162 deep vascular lesions of various types and anatomic sites were evaluated for vessel size, depth, color, and pressure. An algorithm incorporating these characteristics was employed to determine laser parameter settings. Using a high-peak power, long-pulse 1064-nm Nd:YAG laser system, the vascular lesions were then treated.

RESULTS

Within 6 months of follow-up, 80% of treated areas demonstrated a 50% or greater resolution after a single treatment session, with complete clearance shown in 19%. Only minimal and transient side effects were observed. Of note, 74% of areas on the extremities and 83% within the oral cavity showed a 50% or greater resolution after one treatment.

CONCLUSION

Previously challenging deep cutaneous vascular anomalies may be safely reduced or cleared with the use of an appropriate laser system and this algorithm-directed technique. This represents a significant breakthrough in the management of vascular lesions.

Rejuvenation of photoaged skin: 5 years results with intense pulsed light of the face, neck, and chest

BACKGROUND

Photorejuvenation involves the use of lasers or light sources to reverse signs of photoaging. Multiple devices have been shown to be effective over the short-term.

OBJECTIVE

To investigate the long-term clinical results on the face, neck and chest at 4 years using filtered flashlamp intense pulsed light (IPL) for treatment of photoaging changes of telangiectasias, dyspigmentation, and rough skin texture.

METHODS

A chart review of 80 randomly selected patients with skin types I-IV who were treated by IPL during 1996 and 1997 was performed. Photos and patient self-assessment were graded for features of textural smoothness, telangiectasia severity, and blotchy pigmentation into four categories of worse, no change, slightly better (less than 50% improvement) and much better (greater than 50% improvement).

RESULTS

At 4 years following initial treatment, skin textural improvement was noted in 83% of the subjects. Telangiectasias were improved in 82% of subjects, while pigmentation remained improved in 79%. The median number of treatments was 3. The face responded slightly better than the chest or neck. Most common side-effects included temporary mild crusting (19%), erythema (15%) and purpura (6%).

CONCLUSION

Signs of photoaging including telangiectasias and mottled pigmentation of the face, neck, and chest, can be improved by IPL with a long-lasting result. Minimal or no downtime with minimal adverse effects can be achieved with the settings reported. Skin textural smoothing, although not easily quantified, is an additional benefit observed long-term.

Treatment of leg telangiectases with a 532 nm KTP laser in multipulse mode

BACKGROUND

The multiple mode emission emphasizes the efficacy of the KTP laser.

OBJECTIVE

To evaluate the efficacy of a 532 nm KTP laser emitting in multipulse mode for the treatment of superficial 0.5-1 mm leg telangiectases.

METHODS

A 532 nm KTP laser was used in a nonuniform pulse sequence or multipulse mode emission (three stacked pulses of 100 msec, 30 msec, 30 msec, and a delay between pulses of 250 msec), a fluence of 60 J/cm2, and a 0.75 mm collimated spot. No cooling was used. Fourteen female patients (average age 46 years, range 27-57 years), phototypes I-IV were examined with Doppler ultrasound to ensure their big veins were competent. A topography of the telangiectatic network was reported on a tracing plastic frame before each session and 6 weeks after the last one. These frames were digitized and the number of vessels (before and 6 weeks after each session) was determined using imaging software. Side effects, pain, and patient satisfaction were noted.

RESULTS

Moderate pain, immediate erythema and edema, sometimes light scabbing, temporary hypopigmentation rarely, and no matting were observed. After one treatment, vessel clearing was 53% (P <.001). It increased to 78% (P <.001) 6 weeks after two treatments, to 85% (P <.05) 6 weeks after three treatments, and to 93% (NS) 6 weeks after four treatments.

CONCLUSION

This nonuniform pulse sequence or multipulse mode emission emphasizes the efficacy of the KTP laser in this study. It provides a safe and effective treatment that achieved an important reduction of red leg veins telangiectases from 0.5 to 1 mm in diameter, with very few side effects.

Objective assessment of port-wine stains following treatment with the 585 nm pulsed dye laser

Previous studies assessing the treatment of port-wine stains (PWS) with the 585 nm pulsed dye laser have relied on either subjective clinical assessment or in vivo measurement of skin colour alone. The aim of the present retrospective study was to develop an objective method of assessing available pre- and post-treatment photograph pairs. Port-wine stains depicted in photographs of 23 patients following six or more treatment sessions were assessed for changes in colour (DeltaH*) and PWS size by computer image analysis and were compared with a subjective assessment of PWS reduction by a "blinded" physician examining the same images. The post-treatment mean reduction in the PWS assessed by the physician was 39.7%. A global assessment score incorporating values of DeltaH* and PWS size by computer analysis showed a mean reduction of 12%, with a more significant correlation with the physician assessment (Spearman's rank correlation coefficient 0.627; P=0.001) than changes in size or colour alone.