Advances in Techniques for Endovenous Ablation of Truncal Veins

G. S. Munavalli, MD, MHS,^1,2,3 and R. A. Weiss, MD^1,3

1. Department of Dermatology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
2. Division of Dermatology, University of Maryland School of Medicine, Baltimore, Maryland, USA
3. Maryland Laser, Skin and Vein Institute, Hunt Valley, Maryland, USA

ABSTRACT

The latest techniques for endovenous occlusion, i.e., radiofrequency ablation catheters or endoluminal laser targeting water are our preferred methods for the treatment of saphenous-related varicose veins. Clinical experience with endovenous techniques in more than 1,000 patients shows a high degree of success with minimal side effects, most of which can be prevented or minimized with use of tumescent anesthesia. Within the next 5 years, these minimally invasive endovenous ablative procedures involving saphenous trunks should have virtually replaced open surgical strippings.

Key Words:
endovenous occlusion, saphenous related varicose veins, radiofrequency ablation catheters, endoluminal targeting water

Venous disease affects 40%-55% of the population; common symptoms include leg pain, swelling, and skin changes.^1,2 It encompasses a wide spectrum of clinical manifestations, from asymptomatic spider veins overlying the ankles, to bulging branches of the greater or great saphenous vein (GSV) extending across the anterior thigh, to leg swelling and chronic ulceration of the lower medial calf. Venous insufficiency, the most common form of venous disease,² occurs when a high-pressure leakage develops between the deep and superficial systems, or within the superficial system itself (e.g., within GSV, and the lesser or small saphenous vein (LSV), (Figure 1)), followed by sequential failure of the venous valves in the superficial veins. Venous blood escapes from its normal flow path and flows in a retrograde direction down into an already congested leg.

Over time, incompetent truncal veins acquire the typical dilated and tortuous appearance of varicosities. Furthermore, insufficiency can lead to chronic morbidity in the form of ulcerative and edematous skin changes in the lower extremities.

Figure 1: Distributions of the Greater (Great) and Lesser (Small) Saphenous Veins
Figure 2: Clinical improvement 6 weeks after treatment of the LSV with endovenous ablation
Figure 3: CoolTouch CTEV™ 1320nm laser and automatic pullback device (Courtesy CoolTouch, CoolTouch Corp)

Previous methods of treating saphenous vein reflux include vein stripping, ligation and division, echosclerotherapy, and valve replacement. Vein stripping has a failure rate as high as 60%, and has historically required general or spinal anesthesia. Recovery can often take 2-3 weeks. Similar to vein stripping, the reported incidence rate for GSV reflux following high ligation alone is significant, with up to 71% recurrence. Postulated reasons for this include under-recognized anomalous anatomic vascular patterns in the saphenous systems and neo-vascularization.

In 2002, the US FDA approved endovenous laser treatment as a minimally invasive method of ablating incompetent saphenous veins. This in-office procedure uses local anesthesia, thus eliminating the need for general or spinal anesthesia. Unlike the invasive processes of stripping and ligation, obtaining percutaneous access to a vein under local anesthesia and using a form of directed laser energy from the inside to shrink and seal the targeted vein allow for quick patient recovery (Figure 2).

Endovenous ablation was first performed by inserting a bipolar radiofrequency (RF) fiber into a targeted varicose or refluxing saphenous vein and heating from within.³ With more than 60,000 procedures performed worldwide since 1999, radiofrequency shrinkage of veins has become a valuable addition to treating large varicose veins resulting from saphenous reflux. Today, systems are also available that utilize various infrared wavelengths to accomplish endoluminal heating and shrinkage of saphenous trunks. This article will focus on two types of endovenous treatment using laser: laser targeting hemoglobin (810nm, 940nm, and 980nm) and laser: laser targeting water (1320nm).

Utilization of Tumescent Anesthesia

Tumescent anesthesia, or the placement of large volumes of dilute anesthesia in a perivascular position under the direction of duplex guidance, serves several purposes:

• It protects perivascular tissues from the thermal effects of intravascular energy by serving as a heat sink.
• It decreases the diameter of the treated vein to allow for better absorption of energy by the target chromophore and thus, secondarily, reduces intravascular blood for nonspecific coagulation.
• It provides a more effective and safer anesthesia for patients.

Using the tumescent technique, sealing the GSV via the endovenous approach is a painless procedure permitting immediate post-treatment ambulation. In our experience, the incidence of deep vein thrombosis (DVT) as measured by Duplex ultrasound 3-14 days after treatment is 0%.

Endoluminal Laser Ablation Targeting Hemoglobin (810nm, 940nm, and 980nm)

Endovenous laser treatment allows delivery of laser energy directly into the blood vessel lumen in order to produce endothelial and vein wall damage with subsequent fibrosis. Various lasers are used (Table 1). The presumed target for lasers with 810nm, 940nm, and 980nm wavelengths is red blood cells. Steam bubbles are generated as blood is boiled within the lumen, resulting in thrombotic vein occlusion. Direct thermal effects on the vein wall are probably not important. The extent of thermal injury to the tissue is dependent on the quantity of blood in the lumen, the rate of pullback, and the amount of tumescent anesthesia placed around the vein.

The 810nm diode laser appears to have good short-term efficacy in the treatment of the incompetent GSV, with 96% occlusion at 9 months, and a < 1% incidence of transient paresthesia. More recently, a 2-year follow-up of 499 limbs indicated a recurrence rate of less than 7%. However, 90% of the patients contacted experienced degrees of postoperative ecchymosis and varying degrees of discomfort.4 In other series, skin burns have been reported, as have cases of deep venous thrombosis extending into the femoral vein.

Our patients treated with an 810nm diode laser have shown an increase in post-treatment purpura and tenderness. Most of our patients do not return to complete functional normality for 2-7 days as opposed to the 1-day “down-time” with RF closure of the GSV. Recent studies suggest that pulsed 810nm diode laser treatment may be responsible for intermittent vein perforations, and continuous treatment may be safer.5
When using a wavelength strongly absorbed by hemoglobin, such as 810nm, there is a significant amount of intraluminal blood heating with transmission of heat to the surrounding tissue through long heating times.

Temperatures in animal models have been reported as high as 1200oC.5 When we have tried ex vivo vein treatment without blood, the 810nm wavelength simply chars a groove along the inside of the vein. In vivo, varicose veins are not straight segments, but rather saccular and irregular, so that pockets of hemoglobin are frequently encountered which leads to sharp rises in temperature and vein perforations when hemoglobin-absorbing wavelengths such as 810nm are used. Minimizing direct contact with the vein wall for hemoglobin-dependent methods minimizes the charring of the vein wall and probably lowers the postoperative pain levels.

It can sometimes be very difficult to gauge the correct amount of tumescent solution needed to compress the vein and still leave some intraluminal blood (necessary for the mechanism of action). If too much tumescence is used, and hemoglobin is eliminated, there can be charring of the inner wall of the vein, with resulting pain and failure of vein occlusion.

Endoluminal Laser Ablation (1320nm) Targeting Water

In an attempt to circumvent problems associated with hemoglobin-absorbing wavelengths, the 1320nm laser was investigated for endovenous ablation beginning in 2002. US FDA clearance was achieved in September 2004 for treatment of GSV, and in August of 2005 for the obliteration of reflux in the lesser saphenous vein.

Figure 4: 1320 nm wavelength is selective for water as the chromophore. This allows for targeted heating of the vein wall.
Figure 5: Comparison of Greater Saphenous Vein treatment with 810nm vs. 1320nm 48 hours post treatment.

The 1320 nm CoolTouch CTEV™ (CoolTouch) uses a special conducting laser fiber coupled with an automatic pullback device pre-set to pull back at 1mm/sec (Figure 3). Tissue water is the target, and the presence or absence of red blood cells within the vessels is not relevant to the effectiveness of the procedure. This 1.32m wavelength is unique among endovenous ablation lasers in that this wavelength is absorbed only by water and not by hemoglobin (Figure 4).

Our own experience with the 1320nm device reflects a reduction in pain and bruising of 80% as compared with the 810nm device. Having treated more than 200 greater saphenous veins with the 1320nm laser, we have found the incidence of mild pain is 5%, and our success rate of vein ablation is 95% at 2 years. Goldman6 has reported a similar experience, concluding that at 6 months follow-up, a 5-watt, 1320nm intravascular laser with 1mm/sec automatic pullback, delivered through a diffusion-tip fiber, was shown to be safe and effective for treating an incompetent great saphenous vein up to 1.2 cm in diameter (Figure 5).

We believe that there is reduced pain with the 1320nm laser due to reduced vein perforations, less thrombus formation, and more uniform heating. Pain that is experienced after treatment with the 1320nm laser is probably related to heat dissipation into the surrounding tissue, rather than to vein perforations, as the incidence of bruising is extremely low. In our own unpublished studies we have found that emitting 5 watts of 1320nm radiation through a 600µ fiber moving at 1mm/sec in a 2mm-thick vein wall results in a peak temperature of the exterior vein wall of 48oC. Unfortunately, in a saphenous vein, for effective sealing and shrinkage, higher energies must sometimes be utilized. (Figure 5).

The 1320nm water-targeting device appears to be associated with less pain and bruising than 810nm, 940nm, or 980nm hemoglobin-targeting endovenous devices.

References

1. Goldman MP. Sclerotherapy: Treatment of Varicose and Telangiectatic Leg Veins. Baltimore: Mosby (1991).
2. Weiss RA, Feied CF, Weiss MA. Vein Diagnosis and Treatment: A Comprehensive Approach. New York: McGraw-Hill (2001).
3. Weiss RA, Weiss MA. Controlled radiofrequency endovenous occlusion using a unique radiofrequency catheter under duplex guidance to eliminate saphenous varicose vein reflux: a 2-year follow-up. Dermatol Surg 28(1):38-42 (2002 Jan).
4. Min RJ, Khilnani N, Zimmet SE. Endovenous laser treatment of saphenous vein reflux: long-term results. J Vasc Interv Radiol 14(8):991-6 (2003 Aug).
5. Weiss RA. Comparison of endovenous radiofrequency versus 810nm diode laser occlusion of large veins in an animal model. Dermatol Surg 28(1):56-61 (2002 Jan).
6. Goldman MP, Mauricio M, Rao J. Intravascular 1320-nm laser closure of the great saphenous vein: a 6- to 12-month follow-up study. Dermatol Surg 30(11):1380-5 (2004 Nov).