Use of a New Endovenous Laser Device: Results of the 1,500 nm Laser
Article Outline
Background
A new endovenous laser wavelength (1,500
nm diode laser) in the treatment of great saphenous vein (GSV) reflux was evaluated. We studied the occlusion rate at 6 months and noted possible side effects.
Methods
In 129 patients, 158 GSVs were treated using the 1,500nm diode laser. An average linear endovenous energy density of 53.4J/cm and an average endovenous fluence of 32.21J/cm2 were administrated to the vein.
Results
The occlusion rate at 6 months postoperative was 93.3%. Some of the nonoccluded veins closed spontaneously. A postoperative foam treatment was necessary in 3.4% of the treated veins. We found a marked shrinkage of the treated veins. There were limited side effects: moderate or severe ecchymosis in 19%, moderate pain in 1%, moderate periphlebitis in 8.2%, with no paresthesias.
Conclusion
Endovenous laser treatment of the GSV using a 1,500nm diode laser is effective and safe. The marked shrinkage of the treated veins can guarantee good long-term results.
Introduction
A new endolaser wavelength in the treatment of saphenous vein reflux is evaluated in this prospective trial. A 1,500nm diode laser (Intermedic, Barcelona, Spain) was used to obliterate the refluxing great saphenous vein (GSV). We studied the postoperative occlusion rate at 1 and 6 months and the natural change in the diameter of the treated veins after endovenous ablation. Secondary effects such as the occurrence of ecchymosis, postoperative pain, periphlebitis, need for analgesics, and the duration of incapacity to work were studied.
Endovenous laser treatment (ELT) has become a popular minimally invasive alternative to stripping in the treatment of saphenous vein reflux. Several wavelengths have been proposed: 810, 940, 980, 1,064, and 1320nm,1, 2, 3, 4 of which 810, 940, and 980nm are the most commonly used. The light energy delivered from the 1,500nm diode endolaser, like the 1,320nm laser, is preferentially absorbed by water. The mechanism of action of both lasers is light absorption by water in the vein-wall cells.
Heat is generated within the zone of optical penetration by direct absorption of laser energy. Absorption is the primary event that allows a laser or other light source to cause a potentially therapeutic (or damaging) effect on a tissue. Without absorption, there is no energy transfer to the tissue and the tissue is left unaffected by the light. Scattering of light occurs in all biological tissues: blood, vessel wall, perivenous tissue. Due to fluctuations in the refractive index of these media, the propagation of light into the tissue is modified and the scattering affects “where” the absorption will occur, usually reducing the penetration of light into the tissue. Heating decreases with tissue depth as absorption and scattering attenuate the incident beam. Based on the absorption and effective scattering coefficients of the biological tissue, the optical extinction (μeff) can be determined.5, 6
Figure 1 shows absorption (black) and scattering (red) coefficient values as a function of wavelength. Using these values and equation,5 it is possible to determine the optical extinction for the different wavelengths used for ELT (Table I). This table clearly shows that the optical extinction is much higher at 1,500nm (five to nine times higher) compared to 810, 940, 980, and 1,320nm. Interestingly, for these wavelengths, the optical extinction is similar for blood and vessel wall. Since the biological target is the vessel wall, the vein must be drained of its blood before ELT in order to avoid important attenuation of light by the blood “layer” resulting in insufficient energy to heat up the vessel wall. Furthermore, the absence of blood will avoid the potential creation of an additional layer of carbon around the tip. Finally, at the perivenous tissue the exctinction coefficient is five times lower compared to the vessel wall. This means that laser light is less prone to be converted into heat by the perivenous tissue, reducing the risk of local complications.
Fig. 1
Absorption and scattering coefficients of blood relative to wavelength. From Kuenstner and Norris.6
Table I. Extinction coefficients (bold) related to wavelength and different biological tissues
| 810nm | 940nm | 980nm | 1,320nm | 1,500nm | |
|---|---|---|---|---|---|
| Blood | |||||
| μa (mm−1) | 0.16 | 0.25 | 0.28 | 0.38 | 3.0 |
| μ′s (mm−1) | 0.73 | 0.64 | 0.6 | 0.54 | 0.52 |
| μeff (mm−1) | 0.65 | 0.82 | 0.86 | 1.02 | 5.63 |
| Vessel wall | |||||
| μa (mm−1) | 0.2 | 0.12 | 0.1 | 0.3 | 2.4 |
| μ′s (mm−1) | 2.4 | 2.13 | 2.0 | 1.8 | 1.7 |
| μeff (mm−1) | 1.25 | 0.9 | 0.79 | 1.37 | 5.43 |
| Perivenous tissue | |||||
| μa (mm−1) | 0.017 | 0.027 | 0.030 | 0.045 | 0.35 |
| μ′s (mm−1) | 1.2 | 1.1 | 1.0 | 0.9 | 0.84 |
| μeff (mm−1) | 0.25 | 0.3 | 0.3 | 0.36 | 1.12 |
Taking into account the absorption and scattering coefficients of this new wavelength laser (Fig. 1), the 1,500nm laser is at least five times more powerful than the 980nm laser. With less energy, more selective destruction of the vein wall can therefore be obtained.
In this prospective trial we evaluated the clinical results of endovenous laser ablation using the 1,500nm diode laser. Is it possible to achieve good occlusion rates and limited side effects using this 1,500nm diode laser? Can these results be obtained using lower-energy deposits? A prospective study was set up in which various parameters were analyzed.
Materials and Methods
Patient Group
One hundred and twenty-nine patients were scheduled for treatment between March and December 2007. In all patients, the diagnosis of venous incompetence with reflux was made by clinical evaluation and duplex studies. Seventy-four percent of the patients were female (n =95), and 26% were male (n =34). The mean age was 44 years (range 27-80). Patients who had occlusive arterial disease, patients with a known thrombotic or hemorrhagic tendency (incuding oral anticoagulation), and women who were pregnant or planning to become pregnant were excluded, as were patients with a venous diameter >15mm and dilatation of the saphenofemoral junction (SFJ). junction with multiple incompetent side-branches.
In this patient group 158 GSVs were treated. One hundred patients underwent a unilateral treatment and 29 a bilateral treatment. Patients were classified using the CEAP (clinical, etiology, anatomy, pathophysiology) clinical classification: 102 C2, 36 C3, 12 C4, 1 C5, 7 C6.
Ethical approval for this study was obtained by the ethical committee of the Sint-Andriesziekenhuis Tielt.
Technique
Prior to surgery, detailed ultrasound duplex mapping was performed in the standing position, including measurement of the diameter of the incompetent saphenous vein at three reference points (2cm distal to the SF junction, mid-thigh, and knee), using a GE Logiq 9 (GE Healthcare, Waukesha, WI) ultrasound scanner. From these measurements, we calculated the average diameter of the vein. The incompetent side-branches and perforating veins were marked on the skin.
Access to the saphenous vein was obtained by puncture under ultrasound guidance. A below-knee access was made in 27% (n = 44), and in the remaining an above-knee access was made (n = 114). We found a proximal refluxing segment of <15cm in 20 cases. In the vast majority of cases (n = 134) the most distal point of reflux was the point of access. Only in some very long refluxing segments was the access made just below the knee (n = 24).
Prior to laser ablation, tumescent anesthetic was injected profusely around the saphenous vein, under ultrasound control. The injected fluid contained two ampoules (10mL) of lidocaine 1% diluted with 300mL of saline. The veins were treated with continuous retraction at 6 watts at a rate of 1mm/sec. Below the knee the power was reduced to 5 watts.
Perioperative manual compression was avoided since this compression facilitates direct contact between the fiber tip and the vessel wall and thus increases the risk of perforation.
All saphenous vein ablations were accompanied by a Muller phlebectomy. Phlebectomies were not performed near the treated GSV, to avoid interfering with the ecchymosis measurement resulting from the ELT. If the phlebectomy was extended or if a bilateral treatment was performed, only saline was injected and the patient was treated under general anesthesia. All patients were treated in the Trendelenburg position.
Postoperative Care and Follow-Up
A compressive bandage was applied for 3 days postoperatively, followed by compression stockings (class 2) for another 3 weeks. All patients were treated in an outpatient setting and encouraged to return to normal activities as soon as possible. All 129 patients were given a prescription for sodium diclofenac 75mg on discharge, with the instruction to take them only when they became aware of pain or inflammation in the treated leg and to then take two capsules daily.
All patients received prophylactic low–molecular weight heparin (enoxaparin 20mg) for 10 days.
Clinical follow-up was scheduled at 3 days, 1 month, and 6 months postoperatively. Several clinical scores were used: level of analgesic intake, whether or not periphlebitis occurred, incapacity to work, pain score, and ecchymosis. The degree of pain was rated from 0 to 3 (0, no pain; 1, little pain; 2, moderate pain; 3, severe pain). In order to evaluate ecchymosis, we used four grades, in which 0 signified no, 1 mild, 2 moderate, and 3 severe ecchymosis (Fig. 2).
Fig. 2
Ecchymosis score: A 0, almost no ecchymosis; B 1, mild ecchymosis; C 2, moderate ecchymosis; D 3, severe ecchymosis.
Periphlebitis is a common complication of ELT. It is defined as a burning sensation around the treated vein. It usually starts on the fifth postoperative day. Its intensity and duration are variable. This uncomfortable feeling improves with intake of anti-inflammatory drugs. At the clinical review 1 month postoperatively, patients were asked if they had been aware of an inflammatory burning feeling around the treated vein. The intensity was rated from 0 to 3 (0, no burning feeling; 1, slight; 2, moderate; 3, intense).
After treatment, patients were advised to return to normal activities as soon as possible. Incapacity to work was prescribed by the general practitioner. In Belgium the social security system refunds the complete loss of income due to sick leave for employees. This system has the disadvantage of demotivating patients to return fast to work. For this purpose, we looked for the difference in sick leave between self-employed people and employees.
Duplex scans were scheduled at 1 and 6 months. We used the Groupe d'Évaluation des Lasers et de l'Échographie Vasculaire (GELEV) score (Table II) to interpret the occlusion rate. This duplex score makes it possible to evaluate the morphological development of the treated veins. For this purpose, we used the proximal measured diameter of the treated vein, which is located 2cm distal of the SF junction. This diameter was compared in the various outpatient reviews, and the veins were classified using the GELEV score.
Table II. Morphological change after treatment: GELEV score
| Score | 1 month | 6 months | Treatment |
|---|---|---|---|
| 0 | 0 | 1 | 1 foam |
| 1a | 6 (1 foam, 5 ww) | 6 | 3 foam, 3 ww (one 2b, two 3) |
| 1b | 5 (all ww) | 3 | 3 ww (one 3, one 2b, one 1b) |
| 2a | 67 | 3 | |
| 2b | 57 | 10 | |
| 3 | 22 | 67 | |
| 4 | 0 | 57 | |
| Total | 157 | 147 | 11 lost to follow-up |
The results were compared with historical published results using a 980nm laser.
Calculation of Energy Deposits
We use the term linear endovenous energy density (LEED)7, 8 for the energy amount in joules divided by the treated vein length in centimeters. The term endovenous fluence (EF)9 is used for the quotient of delivered energy in joules to the approximated inner vessel surface (calculated using the mean diameter of the three reference diameters measured preoperatively with the patient in the standing position). The advantage of using EF is that it makes it easy to compare energy used in treated veins with a different diameter since the diameter is included in calculating EF.
Statistical Evaluation
Statistical analysis was performed using SPSS 16.0 (SPSS, Inc., Chicago, IL). For correlation analysis, we used the Spearman correlation test. Intergroup variances for unpaired continuous and ordinal data were evaluated nonparametrically using the Mann-Whitney U-test. An α level of significance of 0.05 was used.
Results
The mean length of the treated segment of the GSV was 27.98cm (standard deviation [SD]=8.9) and the mean diameter was 5.89mm (SD=2.0). The average maximal diameter at the SFJ was 7.67mm (SD=3.2).
The average energy applied per unit of length (LEED) was 53.4J/cm (SD=9.2). EF, calculated separately for each patient, averaged 32.21J/cm2 (SD=12.9).
Postoperative ecchymosis is due to vein-wall perforation and/or to the injection of tumescent fluid perioperatively. In this trial ecchymosis was measured on the third postoperative day (first clinical control). We used a visual grading (Fig. 2). In the majority of patients we found no or very limited postoperative ecchymosis. Ecchymosis did not occur in 49.4% (n=78) of the treated legs. A mild type of ecchymosis was noted in 31.6% (n=50), moderate ecchymosis in 17.1% (n=27), and excessive ecchymosis in only 1.9% (n=3). We did not find any correlation between the degree of ecchymosis and use of LEED (Spearman r=0.069, p>0.05) or EF (Spearman r=0.169, p>0.05).
At the clinical review 1 month postoperatively patients were asked how much pain they had during the first 2 postoperative weeks. In the unilateral treatment group (n=100) 93 patients had no pain, six patients had little pain, and only one patient indicated moderate pain. In the bilaterally treated group (n=29) only two patients (6.9%) indicated little pain, while the remainder did not mention having any pain.
Of the unilaterally treated group 36.9% were using analgesics. The average time period of intake of analgesics was 0.78 days (SD=1.4). In the bilaterally treated group 40% were using analgesics during an average time period of 1.74 days (SD=2.8). We did not find any correlation between the applied energy (LEED and EF) and the intensity of postoperative pain (Spearman r=0.072, p>0.05, and r=0.169, p>0.05, respectively) or postoperative analgesics use (Spearman r=−0.040, p>0.05, and r=−0.073, p>0.05, respectively).
Periphlebitis was noted in 14.6% (n=23) of the treated legs: a slight burning sensation around the treated vein was noted in 10 legs, moderate burning in 12 legs, and severe burning in one leg.
One patient complained of hard nodular indurations, and one patient had fever postoperatively, which disappeared after 3 days.
Sick leave was measured depending on the type of work. Ninety-six patients were in gainful employment. Employees had a mean period of sick leave of 10.6 days (range 0-28), while the self-employed had a mean period of sick leave of 3.0 days (range 0-14). We did not find any significant differences between unilateral and bilateral treatment. Self-employed patients returned to normal activities far sooner than employees (Mann-Whitney U, p<0.001). Sick leave thus also depended on social circumstances, and these can explain the relatively long sick leave for employees. Comparing sick leave in different cohort studies is reliable only if the patient population lives in similar social circumstances.
Ultrasound scans were performed at 1 and 6 months postoperatively. At 1 month we checked 157 veins (missed 1) and at 6 months, 147 veins (missed 11). We had a complete occlusion rate of 93.3% at 6 months. We nevertheless treated the nonclosed veins with foam in only five (3.4%) cases. In the other cases the recanalized veins showed a thickening of the vein wall and a filliform open lumen. These patients were scheduled for a further ultrasound review 3 months later (watchful waiting), and the vast majority of these veins closed spontaneously (see “Discussion”). No significant clinical complications were mentioned. We noted a progressive shrinkage of the veins due to the cicatrization of the vein wall. We did not find any correlation between the recanalization rate (GELEV score at 6 months postoperation) and the energy used (LEED and EF) (Spearman r=−0.136, p>0.05, and r=0.176, p>0.05, respectively).
One patient showed some signs of skin pigmentation. All patients with ulcers preoperatively progressed to complete healing. No skin burns, paresthesia, infection, or deep venous thrombosis were found in this series. At the 1-month clinical control, patients were asked if they were satisfied with the received treatment. The satisfaction rate was 100%.
Discussion
This new wavelength laser treatment offers the theoretical advantage of more selective energy absorption in water and, consequently, in the vein wall. Clinically, we found very limited postoperative pain and ecchymosis. Moderate pain was noted in 1% of the unilaterally treated patients and in none of the bilaterally treated patients. In spite of the fact that patients were asked to indicate pain due to the ELT, some pain could be caused by the associated phlebectomy. However, since the vast majority of patients claimed not to feel any pain, this interference is of little clinical importance.
The limited postoperative pain and ecchymosis might be explained by fewer vein perforations. Using a 1,500nm laser correlates with less penetrating ulcerations and more circumferential damage.10 This treatment also shows significant shrinkage of the treated veins. When we examined the morphological change in the treated veins (Table II) at 1 month postoperatively, we found one vein with a proximal recanalization and reflux through a connected tributary vein (GELEV score 1a). This vein was treated by ultrasound-guided foam sclerotherapy. In five cases we found proximal recanalization with some reflux, and in five other cases the vein was partially open and compressible but showed no reflux when the patient performed a Valsalva maneuver (score 1b). In all these veins we saw a thickened vein wall with only a filliform reopening of the lumen. The internal luminal diameter was less than 3mm. Here, we followed a policy of watchful waiting.
The next duplex control at 6 months postoperatively showed complete occlusion of all these 10 veins (two with GELEV score 2b, five with score 3, three with score 4). Nevertheless, at 6 months postoperatively nine new recanalizations were noted. Four of them were treated with foam sclerotherapy (one with score 0, three with score 2a); these veins showed significant reflux when the patient performed a Valsalva maneuver, with an internal diameter of >3mm. In all the other cases we noted a filliform lumen with a thickened vein wall. These five veins were reviewed 2 or 3 months (8-9 months postoperatively) later, and four of them had closed spontaneously. It is important to note that these veins were classified at the first ultrasound review as 2a (six veins) or 2b (three veins). None of the veins with level 3 recanalized.
Theoretically, thrombotic occlusion of the vein occurs after ELT. Some of the light energy is absorbed by the blood, forming a thrombus. Otherwise, blood from side-branches enters the damaged vein and forms a clot. On the other hand, the cicatrization process of the treated vein develops into a fibrotic string (score 4). This process takes several months, and if an intraluminal clot dissolves before the fibrotic process finally closes the vein, we find a recanalization. In most cases this recanalization is temporary and develops into fibrotic occlusion. Similar shrinkage behavior has been noted using 1,320nm11 and 810nm12 lasers. It is difficult to compare this shrinkage process in these different cohorts since the scoring methodology and the control data were different. One difference is the delayed closure of nonclosed veins after treatment with a 1,500nm laser. In total 19 GSVs were not occluded or reopened, but the majority of them closed spontaneously due to the fibrotic process, something we never experienced using the 980nm laser.9 All those patients stayed asymptomatic. Nevertheless five patients were treated with foam. Our indication to perform this procedure was an inner diameter of >3mm and persistent reflux when performing a Valsalva maneuver. Maybe if we waited longer, some of them could have closed spontaneously as well. In total 137 veins at 6-month follow-up had complete occlusion and did not need any additional treatment. At that time, six veins showed nonocclusion but five of them closed spontaneously 3 months later. One had a persistent nonclosure without reflux. Thus, in only five treated GSVs (3.4%, one at 1 month and four at 6 months postoperatively) was foam sclerotherapy indicated, which in our opinion is a very acceptable result.
Using a 980nm laser, short-term efficacy to close the saphenous vein has been reported to be >95%.13 However, studies with a longer follow-up have provided evidence that a variable number of the post-ELT occluded veins (2-20%) undergo recanalization. Recurrences usually occur before 9 months, with the vast majority noted immediately or within 3 months postoperatively.9, 13, 14, 15, 16, 17
When we retrospectively compared the results obtained using the 1,500nm laser with similar results obtained in our practice using the 980nm diode laser,9 we found a comparable patient population (Table III). These patient cohorts were treated in the same hospital, by the same vascular surgeon, and underwent a technically identical procedure except that the study with the 980nm laser was performed with pulsed retraction. The postoperative treatment and follow-up were identical, as were the measured variables. We found no statistically significant difference in occlusion rate (p>0.05, Mann-Whitney U), but the side effects of postoperative pain (p<0.001), ecchymosis (p<0.001), induration along the saphenous vein (p<0.05), and paresthesias (p<0.01) (Table III) were significantly less. Whether the use of a higher energy level in this new type of laser (1,500nm) will result in a higher occlusion rate or more side effects is probable. Pannier et al.18 claimed a 100% occlusion rate using a 1,470nm laser with an average LEED of 107J/cm. They also reported paresthesia rates of 9.5% after 6 months and 7.6% after 1 year, which in our opinion are not acceptable. Maybe the energy we used was somewhat low, but the energy used by Pannier et al.18 was much too high. On the other hand, the use of lower-energy deposits for the 980nm laser treatment could also diminish the side effects, but then a higher recanalization rate would be expected.8
Table III. Characteristics of the two patient cohorts
| 1,500nm diode 6W | 980nm diode 10W9 | |
|---|---|---|
| Number of treated limbs | 158 | 129 |
| CEAP | 102 C2, 36 C3, 12 C4, 1 C5, 7 C6 | 99 C2, 26 C3, 1 C4, 1 C5, 2 C6 |
| Gender | 74% female, 26% male | 74.2% female, 25.8% male |
| Mean diameter | 5.89mm | 6.9mm |
| Mean maximal diameter | 7.67mm | 8.1mm |
| Mean age | 44 years | 50 years |
| Mean LEED | 53.4J/cm | 103J/cm |
| Mean EF | 32.21J/cm2 | 51J/cm2 |
| Occlusion rate at 6 months | 93.30% | 90.70% |
| Ecchymosis | 49.30% | >80% |
| Moderate pain | 1% | 14% |
| Induration along vein | 1.20% | 9.30% |
| Moderate periphlebitis | 8.20% | 9.30% |
| Paresthesias | 0% | 4.60% |
A prospective comparative randomized trial is obviously necessary to substantiate these conclusions.
Conclusion
ELT of saphenous vein reflux using a 1,500nm diode laser appears to be effective and safe. The side effects are very limited, and the treatment is well tolerated, with minimal postoperative pain. With a low-energy treatment (6 watts) we obtained comparable occlusion rates to the use of lower-wavelength lasers. In cases of partial occlusion with a small internal lumen and thickening of the vein wall, a watchful waiting policy is advised. The marked shrinkage of the treated veins due to fibrotic organization can guarantee very good long-term results.
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PII: S0890-5096(09)00156-3
doi:10.1016/j.avsg.2009.06.024
© 2009 Annals of Vascular Surgery Inc. Published by Elsevier Inc All rights reserved.
