Introduction and history

One of the first applications of lasers in dermatology was the removal of vascular lesions. Laser surgery has become the treatment of choice for many vascular lesions. The most common indications for treatment are vascular anomalies including port-wine stain birthmarks (PWS) and hemangiomas, as well as facial erythema and telangiectasias. Vascular specific lasers have seen an evolution from the historically used continuous wave lasers to pulsed lasers that implement the theory of selective photothermolysis, introduced by Anderson and Parrish in 1983.

In 1961, Dr Leon Goldman pioneered the use of lasers with a ruby device. Argon lasers were developed later in the 1960s and improved the color of PWS and hemangiomas, but resulted in unacceptably high rates of scarring and depigmentation due to non-specific heating of the superficial dermis. The theory of selective photothermolysis provided a mechanism to confine thermal injury to the target of interest and minimize collateral damage to surrounding tissue and allowed development of pulsed lasers.

Three components are necessary for selective photothermolysis: (1) a laser wavelength with preferential absorption of the target chromophore, (2) appropriate pulse duration matched to the target size, and (3) a fluence that both treats the target and minimizes non-specific thermal related injury. The ideal pulse duration is equal to or somewhat shorter than the thermal relaxation time of the target vessel. The thermal relaxation time is defined as the time for 50% of the heat to dissipate from the target of interest. A pulse duration that is too short may not be effective, whereas one that is too long may cause heat to dissipate to surrounding structures and cause unwanted thermal injury. The classic target chromophore for vascular lesions has been oxyhemoglobin, which has the greatest absorption peaks at 418, 542, and 577 nm (Fig. 2.1). The laser light is absorbed by oxyhemoglobin, and converted to heat, which is transferred to the vessel wall causing coagulation and vessel closure. Other hemoglobin species have more recently been recognized as appropriate targets, depending on the vascular lesion. For example, venous lesions may benefit from wavelengths of light that target deoxyhemoglobin. The alexandrite laser at 755 nm is close to a deoxyhemoglobin absorption peak and has been used for refractory or hypertrophic PWS, a venocapillary malformation. Methemoglobin absorption has also been recognized as a potential target chromophore.

Figure 2.1 Optical absorption of hemoglobin.

Source: Dr Scott Prahl, http://omlc.ogi.edu/spectra/hemoglobin.

Pulsed dye lasers (PDL) became available in 1986, and were initially developed at 577 nm to target the yellow absorption peak of oxyhemoglobin. It was later realized that, for selective photothermolysis to occur, the laser wavelength did not have to be at an absorption peak for the target chromophore as long as preferential absorption was still present. PDLs shifted to 585 nm, allowing for a depth of penetration of approximately 1.16 mm; 595 nm PDLs later became available to achieve greater depth of penetration. PDLs have also evolved to incorporate longer pulse durations. Early PDLs had a fixed pulse duration of 0.45 ms, whereas currently available PDLs have pulse durations from 0.45–40 ms. Longer pulse durations have the advantage of treating without purpura.

Epidermal cooling was introduced in the 1990s as a means to protect the epidermis, minimizing pigmentary changes and scarring. Cooling also permits the utilization of higher fluences and thus provides greater treatment efficacy. In addition, cooling minimizes discomfort associated with treatment. Modern cooling devices include dynamic spray, contact, and forced cold-air cooling.

Since the PDL penetrates to a depth of only 1–2 mm, other lasers have been developed to treat vascular lesions in an attempt to achieve a greater depth of penetration. The alexandrite laser at 755 nm and neodymium : yttrium aluminum garnet (Nd : YAG) laser at 1064 nm, for example, penetrate up to 50–75% deeper into the skin. Given that the absolute absorption of hemoglobin species is lower at these wavelengths, higher fluences are required.

Intense pulsed light (IPL) devices emit polychromatic non-coherent broadband light from 420 to 1400 nm with varying pulse durations. Filters are implemented to remove unwanted shorter wavelengths of light to treat vascular lesions with blue-green to yellow wavelengths.

The most commonly used vascular lasers and light sources include:

Vascular anomalies classification

The International Society for the Study of Vascular Anomalies (ISSVA) adopted a classification system in 1996 with two main categories. Vascular tumors are characterized by a proliferation of blood vessels, infantile hemangiomas being the most common. Vascular malformations are characterized by vessels with abnormal structure and normal endothelial cell turnover. Vascular malformations can be further subdivided into slow-flow lesions and fast-flow lesions. Capillary malformations, venous malformations, and lymphatic malformations are slow-flow lesions. Arterial malformations and arteriovenous malformations are fast-flow lesions. Complex-combined vascular malformations occur as well.

PWS, a type of capillary malformation, and hemangiomas are the two most common vascular anomalies that present for laser treatment (Table 2.1).

Table 2.1 Comparison of infantile hemangioma and port-wine stain

Port-wine stain birthmarks

Overview

PWS are vascular malformations that are composed of ectatic capillaries and post-capillary venules in the superficial vascular plexus. PWS vessels are characterized by diminished vascular tone and decreased density of nerves, especially those with autonomic function. In most cases, PWS are congenital, though in rare cases they may be acquired. PWS are found in approximately 0.3% of newborns. They tend to occur on the head and neck, although they may appear anywhere on the body. PWS persist throughout life and many thicken with time (Fig. 2.2). Geronemus et al reported that the mean age of hypertrophy is 37 years and, by the fifth decade, approximately 65% of lesions had become hypertrophied or nodular. There may be associated soft tissue overgrowth, leading to functional impairment in areas such as the lip or eyelid. Vascular blebs often form and may bleed with minimal trauma. These lesions are often considered disfiguring and many patients or their families seek treatment. PWS vessels vary in size from 7–300 µm with older patients tending to have larger vessels.

Figure 2.2 (A, B) Hypertrophic port-wine stain not yet treated.

PWS can be associated with various syndromes that are important to identify. A PWS in the V1 distribution raises the question of Sturge-Weber syndrome (SWS), which may have associated glaucoma, seizures, and developmental delay. Klippel-Trenaunay syndrome involves a PWS on an extremity, limb hypertrophy, and associated lymphatic / venous malformations. PWS can also occur in association with arteriovenous malformations in capillary malformation / arteriovenous malformation syndrome.

The goal of treatment of a PWS is to decrease or eliminate the red or sometimes violaceous color, improve appearance, and diminish psychosocial discomfort caused by these lesions. Treatment may also prevent development of blebs that may bleed or become infected. It has been theorized that treating PWS early may prevent hypertrophy as well. The PDL, which is strongly absorbed by oxyhemoglobin, is the most commonly used laser for treatment. Although PDL is effective and approximately 80% improve with treatment, only about 20% of PWS clear completely. Deeper-penetrating lasers have been used in an attempt to improve treatment outcomes. PWS response to laser treatment is variable. A study by Nguyen et al found predictors of improved response include small size (<20 cm²), location over bony areas, in particular the central forehead, and early treatment. A retrospective study by Chapas et al of 49 infants who started laser treatment by the age of 6 months demonstrated an impressive average clearance of 88.6% after 1 year, suggesting that early treatment may be advisable. Early treatment may be more beneficial due to thinner lesions and overall smaller lesions. Other factors must be considered in deciding when to initiate treatment, including anesthesia and the associated risks and benefits.

Huikeshoven et al have shown that PWS may redarken after laser therapy, though recurrent areas are still significantly lighter compared with baseline. This occurrence of redarkening may be due to revascularization that occurs as a response to injury and hypoxia and / or progressive dilatation of residual vessels as a result of decreased autonomic nerves.

Treatment

The PDL is the most commonly used laser to treat PWS. Treatments are typically done at 4–6 week intervals, and it is not uncommon for 10 or more treatments to be performed initially until a plateau is reached or the lesion clears (Fig. 2.3). Larger spot sizes allow for greater depth of penetration and so the clinician should select the largest spot size that will provide sufficient fluence to achieve the desired end point, while confining the treatment to the area of interest. It is advisable to determine the fluence threshold on the darkest portion of the PWS with 1 or 2 test pulses before treating the entire lesion. The fluence is adjusted to achieve the desired end point. For the PDL, the desired end point is immediate purpura. A confluent gray color signifies that the fluence is too high. A cookbook approach to treatment may result in complications.

Figure 2.3 Port-wine stain: (A) pre and (B) post pulsed dye laser treatments.

Pearl 1

Larger spot sizes increase the depth of penetration. For the PDL, treat with the largest spot that will provide adequate fluence and confine the treatment to the area of interest.

Pearl 2

Larger spot sizes produce less scatter of light and may require lower fluences.

Changing the pulse duration may allow targeting of different-sized vessels and can be useful. Dierickx et al identified the ideal pulse duration for PWS treatment to be 1–10 ms. In practice, treatment often begins at 1.5 ms, though this may be adjusted down to 0.45 ms and up to 6 ms. Parameters to consider include 7–10 mm spot size, pulse duration of 0.45–6 ms, and fluence of 5.5–9.5 J/cm² with appropriate epidermal cooling. Lower energies are used for larger spot sizes, with shorter pulse durations, and in patients with darker skin types. Longer pulse durations are advisable in darker skin types. Treatment should start at lower energies and this can be increased if treatments are tolerated well. Parameters vary by device.

Pearl 3

Proper cooling is essential to protect the epidermis and minimize side effects, i.e. scarring and pigmentary changes.

Prior to treatment, it is helpful to outline the borders of the PWS as laser pulses or topical anesthesia can induce erythema that can blur the border. Surgilube may be placed on eyebrows and eyelashes to avoid singeing. Although hair often regrows, permanent hair loss can occur on eyelashes at any age with PDL treatment, given the close proximity of the follicles to the surface. In addition, permanent hair loss can occur on the eyebrows and scalp of young children, in particular those with dark hair.

Pearl 4

Outline PWS borders prior to treatment, as laser pulses can induce erythema that blurs the border. The PWS may be outlined with a marking pen, or with purpuric laser pulses at the start of treatment.

When treating darker skin types, the risk of hypopigmentation and hyperpigmentation can be minimized by using appropriate cooling and longer pulse durations. Treatment intervals may need to be longer to allow for any pigmentation changes to resolve before proceeding with additional treatment. Care must be taken with leg lesions as legs are prone to hyperpigmentation.

Pearl 5

Know, follow, and trust the desired clinical treatment end point, not a setting number.

Use longer pulse durations and / or lower fluences for darker skin.

The alexandrite laser is typically used for PDL-resistant lesions, though it may be implemented as a first-line treatment for hypertrophic violaceous lesions in adults (Fig. 2.4). The end point is a subtle gray-blue discoloration followed by deeper purpura that takes several minutes to develop. A sustained gray color indicates that the fluence is too high, and there is a risk of scarring. Care must be taken not to overlap pulses as scarring can occur. Note that the range of appropriate fluences for alexandrite laser use is quite broad.

Figure 2.4 Violaceous, hypertrophic port-wine stain: (A) pre and (B) post alexandrite laser treatments. Note improvement in color and thickness.

Courtesy of Dr Rox Anderson.

The Nd : YAG laser and combined 595, 1064 nm lasers can also be used for PWS. Although depth of penetration can be increased, there is a narrow therapeutic window with these devices and caution is advised owing to the risk of scarring. It is recommended that these devices be used only by experienced laser surgeons. IPL treatment with appropriate vascular filters has also been reported to be effective for treatment of PWS. Treatment with any of the near-infrared lasers, or IPL, in hair-bearing areas may lead to permanent hair loss.

Treatment of associated vascular nodules can be done by excision or laser. PDL may be used, though several pulses may be required. Stack pulsing can be used, but should be approached cautiously as risk of injury will be increased. Given the limited depth of penetration of PDL, near-infrared lasers such as the alexandrite and Nd : YAG lasers may be necessary. CO₂ and Er : YAG lasers have also been utilized to successfully ablate nodules.

Photodynamic therapy (PDT) has been utilized successfully to treat PWS, primarily in China. Use of systemically administered hematoporphyrin photosensitizers results in prolonged photosensitivity (weeks), which limits use. Alternative photosensitizers, such as benzoporphyrin derivative monoacid ring A and mono-l-aspartyl chlorin e6 (Npe6), have shorter periods of photosensitivity and may offer promising alternatives. PDT may potentially be a useful treatment if parameters can be optimized. Combined photodynamic therapies and PDL has been studied and may improve safety. Recently there has been great interest in improving treatment efficacy by combining light-based removal of PWS with post-treatment anti-angiogenic agents. This approach is currently experimental, but is promising.

Infantile hemangiomas

Venous malformations

Venous malformations present clinically as soft, compressible, non-pulsatile blue-violaceous papules or nodules that increase in size with measures that increase venous pressure, such as the dependent position. Vessel walls may exhibit calcifications, and phleboliths are considered pathognomonic. Venous malformations are slow-flow lesions that may be present at birth, or present later in life as they progress. MRI imaging for larger lesion is advised to assess the extent of the lesion.

Laser treatment can be indicated for small and discrete venous malformations, for example on the lip (Fig. 2.5). The goal is to decrease the size of lesion and at times complete clearance may be possible, though venous malformations have a tendency for recanalization. Multiple treatment modalities are used for larger lesions including surgery and sclerotherapy. Laser treatment may also be performed for larger venous malformations with the goal of debulking prior to surgery. Laser treatment of venous malformations requires a deeper penetrating laser, and the near-infrared lasers, specifically diode or Nd : YAG, are most commonly implemented. Treatment of these lesions is complex and best handled by experienced surgeons. Scherer and Waner described the benefits of Nd : YAG laser therapy for complex venous malformations including tissue shrinkage, improved color, and induction of dermal fibrosis, thus reducing the risk of skin loss in surgery and sclerotherapy. In their hands, swelling lasted approximately 2 weeks, and blistering, dyspigmentation, and scarring occurred in <5% of patients.

Figure 2.5 Venous malformation: (A) pre and (B) post diode laser treatments. There is significant reduction in size and improvement in color. Patient was undergoing further treatments.

Courtesy of Dr Rox Anderson.

Other vascular malformations

Lymphangioma circumscriptum is a microcystic lymphatic malformation characterized by clusters of vesicles that may be clear, yellow, or blood filled. The lesion may have an associated verrucous texture. A common concern for patients with lymphangioma circumscriptum is persistent drainage; CO₂ and Er : YAG lasers can be implemented in an attempt to scar the superficial component and minimize drainage. There have also been reports of successful treatment with PDL for superficial lymphangioma circumscriptum, though the depth of penetration and chromophore target is limited.

Rosacea and telangiectasias

Telangiectasias are small superficial vessels 0.1–1 mm in diameter that are most commonly associated with sun damage or rosacea. There are many other causes of telangiectasias including, though not limited to, connective tissue disease, a host of genodermatoses, and hereditary hemorrhagic telangiectasia. Patients with rosacea often have associated background facial erythema. Lasers and IPL are the treatment of choice for telangiectasias and facial erythema. Flushing can be improved in many patients although recurrence may occur. The most commonly used devices include PDL, KTP, and IPL. Near infra-red lasers, specifically diode and Nd : YAG, have been used to treat deeper or larger-caliber vessels. Treatment must be tailored, taking into account vessel caliber, skin type, and a patient’s ability to tolerate purpura.

Typically 3–4 monthly non-purpuric laser treatment sessions with PDL produce a significant reduction in erythema and telangiectasias. (Fig. 2.6) Typical settings include 7–10 mm spot, 6 ms pulse duration, 6–9 J/cm² with epidermal cooling. Lower energies are used with larger spot sizes. Lower fluences should be used for patients with intense facial erythema. Lower fluences and longer pulse durations are advisable in darker skin types. Parameters vary by device. Residual telangiectasias can then be treated with purpuric or non-purpuric settings. Pulse durations of 6 ms and above are typically non-purpuric. Pulse durations of 1.5 ms and 3 ms are likely to induce purpura. Telangiectasia may respond in fewer treatment sessions, and purpuric treatments may be more effective. The end point for treating vessels is vessel clearance, a transient blue coagulum (Video 1), or purpura.

Figure 2.6 Rosacea: (A) pre and (B) post four pulsed dye laser treatments.

Vessels around the nasal ala can be more challenging to treat, and greater efficacy may be achieved with judicious stacking of non-purpuric PDL pulses. Larger caliber vessels on the nose may require even longer pulse durations and higher fluences. A recent study of 18 patients with PDL/KTP laser resistant nasal telangiectasia treated with a newer generation PDL utilizing a 40 ms pulse duration and 3 mm × 10 mm elliptical spot showed complete clearance in 10 patients, and >80% improvement in 8 patients.

Background erythema may be treated before or after treating telangiectasias. A cold pack can be applied post-treatment to minimize swelling. Sleeping with several pillows to keep the head elevated can also be helpful if swelling occurs. Rosacea patients should be advised that treatment will significantly reduce erythema and telangiectasias, though maintenance treatments are to be expected as laser is an effective treatment, not a cure.

IPL is also beneficial for the treatment of facial erythema and telangiectasias. The KTP laser may be used to trace individual vessels, with the advantage of no purpura. There is relatively stronger absorption of hemoglobin at 532 nm and care must be taken in patients with darker skin types. The Nd : YAG laser may also be used to treat refractory nasal vessels and facial reticular veins, though the risk of scarring is increased.

Other vascular lesions

Cherry angiomas

Cherry angiomas are the most common vascular growths of the skin. Cherry angiomas are benign proliferations that tend to be highly responsive to laser treatment. The PDL is commonly used to treat angiomas. The end point is purpura (Fig. 2.7). Clearance often occurs with one treatment although there are resistant lesions and larger lesions may require multiple treatments. The KTP laser or IPL may also be utilized.

Figure 2.7 Cherry angiomas: (A) pre and (B) immediately post pulsed dye laser with expected purpura.

For larger and thicker angiomas, an initial pulse can be delivered while performing diascopy (compression with a glass slide) to treat the deeper component. After time for cooling, a second pulse may be placed to treat the more superficial component (if the lesion has not become purpuric). Spider angiomas are treated in a similar manner.

Suggested settings with the PDL are 5–7 mm spot, 1.5 ms pulse duration, 7–10 J/cm², with appropriate epidermal cooling. Settings may need to be adjusted for patients with darker skin types. Parameters vary by device. Cherry angiomas may also be treated with electrodesiccation and shave excision.

Approach to treatment of vascular lesions

A pre-treatment consultation is advisable, to include a discussion of the amount of improvement expected, number of treatments, expected treatment effects such as erythema, purpura, and swelling, potential adverse effects, and aftercare required (including sun protection and avoidance of trauma). Photos before each treatment are recommended.

Eye protection is essential during treatment. If the treatment area is on the face but outside the orbital rim, metal goggles should be placed over the patient’s eyes. Stick-on laser shields with appropriate wavelength protection are useful but careful adherence to the skin is important. An alternative to protect infants and young children’s eyes is multiple layers of gauze and a firm gloved hand. Pressure should not be placed on the eye itself, but on the orbital rim. Care must be taken with this approach so that movement of the patient does not expose the eyes. If the treatment area is within the orbital rim, metal eyeshields that are placed under the eyelids and over the cornea must be used. These should be placed with care to avoid corneal abrasions.

Many vascular lesion treatments can be done without anesthesia, for example patients with rosacea and telangiectasias. Topical anesthetics can cause blanching of the skin, theoretically decreasing treatment efficacy. Vascular anomalies may be treated with or without anesthesia, taking into account the patient’s age, extent of lesion, and preference. Deeper lesions such as venous malformations, or more extensive lesions, may require intralesional lidocaine or nerve blocks. For local infiltration, lidocaine without epinephrine is generally used to minimize vasoconstriction.

The approach to treating infants and young children with regards to anesthesia varies widely. There is evidence that early treatment of PWS improves treatment outcome. Treatment without anesthesia in young children may be appropriate for a limited number of pulses. Topical anesthesia can be beneficial, though its use in infants and small children is limited so as not to exceed the maximum recommended dose per package inserts and, as noted above, vasoconstriction can occur. Ulcerated lesions have higher absorption of topical anesthetics and it is advised not to apply topical anesthetics to ulcerated lesions. General anesthesia offers the advantage of avoiding fear and pain in children who will need multiple procedures. It also allows easy placement of the required corneal shield for treatment of eyelid lesions. However, there are risks of general anesthesia. Studies have documented that in healthy patients with vascular lesions the risk is low; however, advantages and disadvantages need to be considered and discussed with the patient and family.

Side effects and complications

The risk from laser treatment of vascular lesions primarily includes scarring and pigmentary changes. The risk of scarring with the PDL is <1%, but is higher for the near-infrared lasers. Scarring can be minimized by performing test pulses and assessing appropriate tissue response before treating the entire lesion. Lasting gray and white discoloration can be signs of necrosis. Pigmentary changes are often transient, although permanent hypopigmentation can occur and can be minimized by avoiding treating tan patients, proper sun protection pre / post treatment, and modifying parameters in darker skin patients. The darker the patient’s skin type, the higher is the risk of pigmentary changes. Use of PDL is much more difficult in patients with skin types V and VI. Treatments are less effective owing to melanin blocking light penetration and risk of side effects including pigmentary change and scarring, is higher. In the future, treatments like photodynamic therapy might offer these patients a better treatment option.

Swelling may also occur with PDL, though is usually mild and transient, resolving within 24–72 hours. Swelling can be more significant when treating vascular malformations with near-infrared lasers that penetrate deeper and with non-purpuric multiple-pass PDL laser technique. More extensive lesions on the lips and tongue may require oral prednisone before treatment to minimize swelling.

Risk of ulceration and scarring is higher with longer wavelength lasers including the alexandrite and Nd : YAG. Use of these lasers for vascular lesions can require very high energies. These devices should be used cautiously and by clinicians familiar with their use who are prepared to carefully monitor skin effects during and after the procedure. The Nd : YAG in particular has a very narrow therapeutic window.