Endovenous laser ablation for the treatment of varicose veins

Keywords:laser, treatment, medical, fiers,  Time:30-11-2015

A physical examination of the patient’s leg may reveal a characteristic pattern of varicosities that are commonly associated with reflux of a specific vein. For example, GSV reflux often produces varicose veins along the medial aspect of the leg. Anterior thigh circumflex (or anterolateral) vein incompetence produces varicose veins along the anterior thigh. Insufficiency of the Giacomini vein may cause varicose veins around the popliteal fossa; however, varicosities in this area can also originate from SSV or perforating vein insufficiencies. Certain patterns of varicosities suggest that the underlying venous insufficiency actually originates outside the venous system of the leg. Groin varicosities are usually due to iliac vein or gonadal vein insufficiencies, and varicosities on the posterior inferior thigh are due to inferior gluteal vein insufficiency (6–8). It is important to delineate the venous insufficiency that has caused the present varicose veins before treatment. Imaging studies are generally not necessary for diagnosis, but a thorough examination of the extremity with color Doppler US (CDUS) is important. US examination must be performed while the patient is standing. The superficial veins distal to the knee can also be examined with CDUS while the patient is sitting. CDUS can assess the anatomy and physiology of the lower extremity venous system. It can evaluate acute and occult DVT, superficial thrombophlebitis, and reflux of the superficial, deep and perforator veins. Although varicose veins may cause varying degrees of discomfort or cosmetic concerns, they are rarely associated with significant medical complications. Skin pigmentation, infection, superficial thrombophlebitis, and venous ulceration are possible complications. Although very rare, an external hemorrhage resulting from the perforation of a varicose vein and pulmonary embolisms originating from a varicose vein thrombosis have been reported (9).

Endovenous laser ablation

The indications for treatment are largely based on the patient’s preferences. The most common indication for EVLA is insufficiency of the GSV or SSV visualized using CDUS. However, the treatment choice is also affected by symptoms, costs, potential for iatrogenic complications, and the presence or absence of deep venous insufficiency. Patients have CEAP scores ranging from C2 to C6. In addition to primary truncal varicosities, accessory and perforating veins, recurrent truncal varicosities, varicosities in patients with post-thrombotic syndrome after a DVT and Klippel-Trenaunay syndrome have been treated successfully with EVLA. There are no absolute contraindications for EVLA (10). However, EVLA is not performed during pregnancy or for woman planning to become pregnant during the follow-up period. Severe peripheral artery disease can be a relative contraindication because laser fibers energy can damage small arterial branches around the vein in patients with compromised arteries. Allergies to local anesthetic agents and severe hypercoagulability syndromes are relative contraindications. A history of a previous DVT or concomitant deep vein insufficiency is not an absolute contraindication, and patients with these conditions have been treated successfully with EVLA. However, the risk/benefit ratio should be carefully evaluated for patients with a history of a DVT or deep venous insufficiency.

Sedation

The majority of physicians use local anesthesia for needle punctures and tumescent anesthesia to prevent pain that would originate from the effects of surgical laser fibers energy on the venous wall. A number of centers use epidural and general anesthesia. Intravenous conscious sedation, mostly in combination with dormicum and fentanyl citrate, is another option. These two medications have a rapid onset of action and a short duration. They decrease anxiety related to the procedure, relieve pain, and have an amnestic effect, which is preferred for some patients. Intravenous conscious sedation can be performed without the supervision of an anesthesiologist. US-guided femoral and sciatic nerve blocks have been used with varicose vein surgery but rarely for EVLA (11).

Mechanism of endovenous laser ablation Laser generators generally use a 600nm laser fiber to deliver the energy. Laser energy generates high-energy, bundled light that is monochromatic (one wavelength), coherent (in phase), and collimated (photons run parallel). The mechanism of the laser is not entirely clear, but a thermal reaction after the laser exposure is the suspected mechanism. The produced heat may reach up to 800°C at the tip of the fiber and results in the formation of steam bubbles. The bubbles cause the blood to boil and induce thermal injuries to the venous endothelium. The intravascular heat decreases to 90°C at 4 mm from the laser tip. Steam bubbles that form at the tip of the fiber dissipate quickly and pose no systemic risk of tissue burns around the vein. Histological studies show that EVLA damages the endothelial and intimal layers, the internal elastic lamina and the media to some degree. The adventitia is rarely affected (12). Delivering adequate energy is crucial in achieving a successful ablation of the treated vein. Regardless of which technique is used for EVLA, substantial heat transfer to the vein wall is necessary to obtain a durable occlusion of the treated vein. Fluence (Joules/cm2) is the most important parameter to quantify the amount of energy delivered. The amount of energy in Joules (J) depends on the power (in watts) and the duration of exposure of the laser beam to the area (energy=power×time). Because the surface area of the venous wall is difficult to measure, most studies report Joules/cm instead of Joules/cm2 as a marker of fluence. A multivariate analysis showed that the amount of energy administered during EVLA is an independent predictor of the GSV occlusion (13). Studies have indicated that the administration of a linear energy density of ≥80 J/cm2 is usually sufficient to achieve an effective ablation during short-term follow-up (14). Energy dosing dependent on diameter of the vein has been proposed, i.e., the use of higher energy levels for large diameter veins and lower energy levels for small diameter veins (15). To support this hypothesis, a histological study demonstrated that the optimal thermal tissue damage in the venous wall was obtained in veins <9.7 mm in diameter (12). The amount of energy delivered depends on the wattage and duration of the laser energy over the surface of the vein wall. The use of 10–20 W is the most common practice, but wattages as high as 30 W have also been used.

All wattages from 10 W to 30 W appear to be sufficient to achieve an adequate ablation. However, there is not much evidence comparing the effectiveness of EVLA with different powers. A recent randomized study with a small patient population suggested that EVLA using 30 W was more effective than 15 W using a 940 nm diode laser (15). Another small case series showed that 11 W was as effective as 15 W, and it was associated with fewer side effects (16).  All currently available laser wavelengths have been successfully used to treat venous insufficiency. The primary mechanism responsible for delivering the laser energy to the vein wall is the same for all wavelengths: the generation of steam bubbles. It appears that all laser wavelengths used for EVLA work well, and no single wavelength has proven superior to the others (17, 18).  Using the pulse mode or continuous mode usually does not influence the effectiveness of the outcome. The major advantage of the continuous mode is that duration of treatment is shorter. The pulse mode is considered to have a higher risk of adverse events, such as microperforation (19).

Technique EVLA can be performed under local tumescent anesthesia in an outpatient setting. The procedure varies among centers. The technique described below is one of the most commonly used techniques. The target vein is identified using US from the ankle to the SFJ. The saphenous nerve is distant from the GSV above the knee compared to below the knee. Some practitioners prefer to cannulate the GSV at the level of the knee so as not to harm the saphenous nerve, which is prone to injury with ablations below the knee. Venous access is obtained by a needle puncture under US guidance. Needle puncture can cause venous spasm at the access site; then, the vein can be punctured again a few cm above the first puncture site. A 21 G needle is preferred as venous trauma and spasm will be less likely. After entering the vein, a guide wire (mostly J tip or a straight tip) is inserted. If the varicose vein is tortuous, has a small diameter, has a large dilated branch emanating from it, or contains thrombotic, sclerotic segments (after a DVT or a previous EVLA), advancing the wire can be difficult. In such cases, US examination of the area to visualize the tip of the wire, rotating the wire, or exchanging the wire for a hydrophilic one usually solves the problem. If severe tortuosity or obstructions of the vein cannot be crossed, then a second (or even a third) puncture can be performed at higher levels, and ablation can be completed segment by segment. After the guide wire is in place, the needle is removed, a small incision is made at the skin, and a long introducer sheath is inserted. The tip of the sheath is located at the SFJ; the laser fiber is inserted through the sheath so that the tip of the laser fiber is positioned 1–2 cm distal to the SFJ and 1–2 cm away from the tip of the plastic introducer sheath using US guidance. One should ensure that the laser tip lies beyond the end of the catheter before activating the laser energy. Local tumescent anesthesia (5 mL epinephrine, 5 mL bicarbonate and 35 mL 1% lidocaine diluted in 500 mL saline or prilocaine 2% without bicarbonate, diluted in 500 mL saline) is then injected along the entire course of the saphenous vein from the cannulation site up to the SFJ under US guidance using a syringe or an automated pump. The needle tip is positioned as close to the vein wall as possible, and the solution is injected. It is not a problem if the tip of the needle touches the vein wall. The solution will remain in the saphenous fascia mostly; however, it will also diffuse to extrafascial areas. For one leg, 250–500 mL of solution is usually sufficient. The tumescent anesthesia has three functions:  1) it protects the perivenous tissue from the effects of laser energy via a cooling effect,  2) it removes the blood from the lumen by collapsing the vein, increasing the effectiveness of the laser ablation, and  3) it increases the surface area contact between laser tip and the vein wall. The act of forcing the blood from the vein prior to ablation is important because it allows for ablation of the vein wall and does not cause a thrombosis within the lumen. If the venous lumen cannot be completely collapsed, elevation of the leg may help. Before activation of the laser, each person in the room should wear protective laser goggles. The parameters used, including the power, the wavelength, and the speed at which the laser fiber is pulled back, are variable. Patients are usually discharged with an anti-inflammatory medication, such as diclofenac 50 mg taken three times daily for one or two weeks or as needed. Elastic bandages or class II (20–30 mmHg) graduated supporting stockings are recommended for one to three weeks. Compressive stockings not only compress the vein and help to increase the effectiveness of the treatment, but they also decrease the patient’s postprocedural discomfort.

Conclusion

Since a decade after its introduction, EVLA appears to be a safe and effective treatment of venous insufficiency. As a minimally invasive technique, it is a popular choice for both patients and physicians. The procedure has high immediate technical success, a short recovery time, and good cosmetic results. Minor complications are frequent but usually temporary and self-limited, and major complications are rare.