Advanced Techniques in Dermatologic Surgery - part 10

358 Weiss and Goldman and amount of tumescent anesthesia placed around the vein. A uniform layer of blood circumferentially around the fiber will yield the best results with the hemoglobin targeting wavelengths. One in vitro study model has predicted that thermal gas production by laser heating of blood in a 6mm tube results in 6mm of thermal damage (23,24). These authors used a 940nm diode laser with multiple 15-J, 1sec pulses to treat the GSV. An median of 80 pulses (range, 22– 116) were applied along the treated vein every 5–7mm. Histologic exam-ination of one excised vein demonstrated thermal damage along the entire treated vein with evidence of perforations at the point of laser application described as ‘‘explosive-like’’ photo-disruption of the vein wall. This produced the homogeneous thrombotic occlusion of the vessel. Since optical properties of a 940nm laser beam within circulating blood is that it can only penetrate 0.3mm, the formation of steam bubbles is the mechanism of action of heating surrounding tissue (24). Initial reports have shown this technique with an 810nm diode laser to have good short-term efficacy in the treatment of the incompetent GSV, with 96% or higher occlusion at 9 months with a less than 1% inci-dence of transient paresthsia (25,26). Most patients, however, experience major degrees of post-operative ecchymosis and discomfort. Skin burns have observed by one of the authors (RAW). Deep venous thrombosis extending into the femoral vein have also been recently reported with endovenous laser treatment (27). 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 ‘‘downtime’’ with RF ClosureTM of the GSV. There is even less downtime with CTEVTM, discussed in the next section. Recent studies suggest that pulsed 810nm diode laser treatment with its increased risk for perforation of the vein (as opposed to continuous treatment which does not have intermittent vein perforations but may have irregular areas of perforation) may be responsible for the increase symptoms with 810nm laser vs. RF treatment (28). Our experience with trying to vary the fluence and treating with a continuous laser pull back vs. pulsed pull back has not resulted in an elimination of vein perforation using an 810nm diode laser. A longer wavelength such as 940nm has been hypothesized to pene- trate deeper into the vein wall with resulting increased efficacy. A report of 280 patients with 350 treated limbs with 18month follow-up demon-strated complete closure in 96% (29). Twenty vein segments were exam-ined histologically. Veins were treated with 1sec duration pulses at 12 J. Perforations were not present. When the fluence was increased to 15 J with 1.2- and 1.3-sec pulses, microperforations did occur and were said to be self-sealing. The author suggests that his use of tumescent anesthesia as well as the above mentioned laser parameters are responsible for the lack of significant perforations and enhanced efficacy. A clinical study using an endoluminal 1064nm Nd:YAG laser in the treatment of incompetent GSV in 151 men and women with 252 treated limbs was reported (30). Unfortunately, the surgeons also ligated the SFJ, Endovenous Elimination with Radiofrequency or Laser 359 which did not allow for a determination of the efficacy of SFJ ablation. Spinalanesthesiawas used andthelaser wasused at10–15W of energywith 10sec pulses with manual retraction of the laser fiber at a rate of 10 sec/cm. Skin overlying the treated vein was cooled with cold water. Unfortunately, this resulted in superficial burns in 4.8% of patients, paresthesia in 36.5%, superficial phlebitis in 1.6%, and localized hematomas in 0.8%. COOLTOUCH CTEVTM ENDOVENOUS TREATMENT In an attempt to bypass the problems associated with laser wavelength absorptionofhemoglobin,wehavedevelopeda1320nmendolumenallaser. At this wavelength, tissue water is the target and the presence or absence of red blood cells within the vessels is unimportant. The CoolTouch CTEVTM treatment is an endovenous ablation method using a special laser fiber coupled to the intraluminal use of an infrared 1320nm wavelength with an automatic pullback device pre-set to pullback at 1mm/sec (Fig. 5). This 1.32 micron wavelength is unique among endovenous ablation lasers in that this wavelength is absorbed only by water and not by hemoglobin. This makes it significantly different from the other (hemoglobin targeting) wave-lengths used for endovenous laser treatments. In our opinion and experi-ence, the CoolTouch CTEVTM at 1320nm is significantly superior to the other endovenous laser methods both by virtue of the water absorption and the automatic pullback device (31). When using a wavelength strongly absorbed by hemoglobin, such as 810nm,thereis alotofintraluminal bloodheatingwithtransmissionof heat tothesurroundingtissuethroughlongheatingtimes.Temperaturesinanimal models have been reported as high as 1200C (28). When we have tried ex vivoveintreatmentwithoutbloodwiththefiberincontactwiththeveinwall, the 810nm wavelength simply chars the inside of the vein. When blood is added to exvivoveins and is thentreatedwith 810nm, numerous vein explo-sions are observed (personal communication, Dr. M. Hirokawa, Tokyo, Japan, 2005). Minimizing direct contact with the vein wall for hemoglobin-depen-dent methods minimizes the charring of the vein wall and probably lowers the post-operative pain levels. Ideally for a hemoglobin absorbed wave-length to work, it would be best to have a well-defined layer of hemoglobin between the fiber and the vein wall. In the real world, however, varicose veins are saccular and irregular pockets of hemoglobin are frequently encountered leading to sharp rises in temperature and vein perforations when using hemoglobin absorbing wavelengths such as 810nm. Using tumescent anesthesia with a hemoglobin targeting wavelength, itcanbeverydifficulttogaugethecorrectamounttocompresstheveinsince some hemoglobin is necessary for the mechanism of action. If too much tumescence is used, there can be charring of the inner wall of the vein with-out heating of the vein wall, with resulting pain and failure to close the vein. For all these potential obstacles to ideal treatment conditions for 810nm, 940nm, or 980nm, it makes far more sense to use a water absorbing 360 Weiss and Goldman Figure 5 CoolTouch CTEVTM 1320nm laser and automatic pullback device. wavelength once cannulated within the vein. Therefore, the 1320nm wave-length for use in endovenous ablation was explored and clinical trials per-formed resulting in FDA clearance in September 2004 for treatment of the greater saphenous vein. By August 2005, sufficient data for approval for obliteration of reflux in the lesser saphenous vein were cleared by the FDA. Percutaneous approaches to smaller leg telangiectasias indicate that deeply penetrating laser wavelengths with significant deoxyhemo-globin absorption, such as 1064nm Nd:YAG, have the most utility. When veins are targeted through the skin, one exploits the concept of selective photothermolysis. By targeting deoxyhemoglobin, cutaneous Endovenous Elimination with Radiofrequency or Laser 361 leg vessels absorb preferentially to surrounding water, collagen, and other structures. This allows selective destruction of tiny blood vessels without heating surrounding structures. The mechanism of this destruc-tion by 1064nm laser must be clearly understood by the user. The clinical observation is immediate photodarkening and coagulation. Histologi-cally this is represented by perivascular hemorrhage and thrombi with vessels fragmentation (32). This ultimately leads to vessel clearance in about 75% of targeted areas over a 3-month time frame (33). For the cutaneous approach, this is clearly state-of-the-art but this is not the best approach for endovenous laser ablation in which selective photothermo-lysis is not a factor. Endovenous ablation requires maximizing vein shrinkage and closure with the least amount of blood coagulation and the maximum amount of vein wall contraction. We know from earlier methods invol-ving electrosurgical blood coagulation that the long-term success rates based on coagulation of blood are very low (34,35). On the contrary, success rates for radiofrequency vein shrinkage specifically avoiding coagulation of blood are very high (5,13,36). Recently, Proebstle and col-leagues designed a study that answers the question of whether endove-nous ablation is best accomplished by hemoglobin heating or the approach of using water around the collagen in the vein wall as a target (37). He has had extensive experience with the 940nm wavelength for endovenous ablation (38). As shown by Proebstle et al., there is a clear advantage of targeting water over hemoglobin when performing endove-nous laser. There is a statistically reduced rate of pain post-operatively with a higher rate of success while at the same time applying lower energy. This results in greater safety and efficacy for the patient, our own experience reflects this, with a reduction in pain and bruising of 80% when switching from 810nm endovenous to 1320nm endovenous. Having treated over 200 greater saphenous veins with 1320nm, our incidence of mild pain is 5%. No significant pain interfering with walking has been observed. A typical clinical result is shown in (Fig. 6). Based on our experience we believe that there is reduced pain reported with 1320nm vs 940nm probably due to less vein perforations and more uniform heating by 1320nm targeting water in the vein wall. Rarely, patients experience mild pain after 1320nm, but this is probably related to heat dissipated into surrounding tissue, not vein perforations. This might be minimized by using the minimal effective energy to shrink the vein. In our own unpublished studies we have found that emitting 5W of 1320nm through a 600-m fiber moving at 1 mm/sec in a 2-mm thick vein wall, the highest temperature recorded on the exterior of the vein wall was 48C. Unfortunately in a saphenous vein, for effective sealing and shrinkage, higher energies must sometimes be utilized. In the Proebste et al. (37) study, 8W of 1320nm were employed to have the highest intraluminal occlusion and shrinkage but probably accounted for the post-operative pain incidence. We believe that effective energy for vein sealing in our practice is mostly between 5 and 6, thus minimi-zing post-operative pain to less than 5%. In summary, our experience 362 Weiss and Goldman Figure 6 Clinical result seen with CoolTouch CTEVTM 1320nm laser. (A) Before treat-ment. (B) After 6 weeks. There is marked improvement of a varicosity asso-ciated with reflux of the greater saphenous vein. and those of others indicate that 1320nm water targeting vs. 810nm, 940nm, or 980nm hemoglobin targeting endovenous occlusion is gentler, leading to far less bruising and post-operative pain. TECHNIQUE OF COOLTOUCH CTEVTM ENDOVENOUS TREATMENT The patient is evaluated and marked in an identical manner as with RF ClosureTM of the GSV. An appropriate entry point is selected similar to RF. This is usually just below where reflux is no longer seen in the greater saphenous vein. For the majority of patients in our series this is at a point just above or below the knee along the course of the GSV. A sheath is placed in the entire length of the vein to be treated up to the sapheno-femoral junction. Tumescent anesthesia is then injected along the vein and injected subfacially to separate and dissect the targeted vein, and to provide a layer of thermal protection around the vein. Some blood is always in the vein and that gets gently heated from its water content. Direct fiber contact with the vein wall is not important as the energy for heating water is propelled in an arcing field from the distal end of ... - tailieumienphi.vn