A 2 years follow-up study of endovenous 980nm laser treatment of the great saphenous vein: Role of the blood content in the GSV

Commonly Used Endovenous Laser Ablation (EVLA) Parameters Do Not Influence Efficacy: Results of a Systematic Review and Meta-Analysis

OBJECTIVES

The objective of this systematic review and meta-analysis was to summarise available randomised controlled trials (RCTs) of EVLA efficacy, and to define the differences in success rate of variations in wavelength, administered energy, outcome definition, and follow up period.

METHODS

A literature search was conducted in Embase, Medline (Ovid-SP), Cochrane Central Database, and Web of Science from inception to November 2017. RCTs with follow up of more than three months were included. The studied outcome was the proportion of patients with EVLA treatment success, defined as absence of reflux or occlusion of the great saphenous vein (GSV). Pooled proportions of anatomical success were compared. Subgroup and meta-regression analysis included wavelengths (short [810, 940, and 980 nm], long [1470, 1500, and 1920 nm]), amount of energy (≤50 J/cm, > 50 J/cm), follow up (≤1 year, > 1 year), outcome definition (occlusion, no reflux), and quality of the studies (low risk of bias, unclear/high risk of bias).

RESULTS

Twenty-eight RCTs, with a total of 2829 GSVs were included. The overall success rate of EVLA was 92% (95% CI 90-94%, I² = 68%). In subgroup analysis, no statistically significant differences were found for long or short wavelengths (95% [95% CI 91-97%] vs. 92% [95% CI 89-94%], p = .15), high or low administered energy (93% [95% CI 89-95%] vs. 92% [95% CI 90-94%], p = .99), long or short follow up (89% [95% CI 84-93%] vs. 93% [95% CI 91-95%], p = .13) and outcome definition (occlusion group 94% [95% CI 91-96%] vs. absence of reflux group 91% [95% CI 87-94%], p = .26). Studies with low risk of bias reported a significantly higher success rate than high or unclear risk of bias (93% [95% CI 90-95%] vs. 89% [95% CI 83-93%], p = .04).

CONCLUSIONS

The overall success rate of EVLA is high (92%), even with increasing follow up. Commonly used parameters of EVLA (wavelength, administered energy, and outcome definition) have no influence on the treatment success rate.

Investigation of endovenous laser ablation of varicose veins in vitro using 1.885-μm laser radiation

This paper presents the results of endovenous laser ablation (EVLA) of varicose veins in vitro using radiation of a solid-state laser based on the crystal LiYF4:Tm, with a wavelength of 1.885 μm and power output of around 3 W. An experimental series with saline solution and red blood cell (RBC) suspension in the venous lumen was performed to identify the impact of a heated carbonized layer precipitated on the fiber end face versus the efficiency of EVLA. Results of these experiments confirmed that the presence of a heated carbonized layer on the fiber end face increases the efficiency of EVLA.

Endovenous ablation (radiofrequency and laser) and foam sclerotherapy versus open surgery for great saphenous vein varices

BACKGROUND

Minimally invasive techniques to treat great saphenous varicose veins include ultrasound-guided foam sclerotherapy (UGFS), radiofrequency ablation (RFA) and endovenous laser therapy (EVLT). Compared with flush saphenofemoral ligation with stripping, also referred to as open surgery or high ligation and stripping (HL/S), proposed benefits include fewer complications, quicker return to work, improved quality of life (QoL) scores, reduced need for general anaesthesia and equivalent recurrence rates. This is an update of a review first published in 2011.

OBJECTIVES

To determine whether endovenous ablation (radiofrequency and laser) and foam sclerotherapy have any advantages or disadvantages in comparison with open surgical saphenofemoral ligation and stripping of great saphenous vein varices.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched January 2014) and CENTRAL (2013, Issue 12). Clinical trials databases were also searched for details of ongoing or unpublished studies.

SELECTION CRITERIA

All randomised controlled trials (RCTs) of UGFS, EVLT, RFA and HL/S were considered for inclusion. Primary outcomes were recurrent varicosities, recanalisation, neovascularisation, technical procedure failure, patient QoL scores and associated complications.

DATA COLLECTION AND ANALYSIS

CN and RB independently reviewed, assessed and selected trials which met the inclusion criteria. CN and RB extracted data and used the Cochrane Collaboration's tool for assessing risk of bias. CN and RB contacted trial authors to clarify details as needed.

MAIN RESULTS

For this update, eight additional studies were included making a total of 13 included studies with a combined total of 3081 randomised patients. Three studies compared UGFS with surgery, eight compared EVLT with surgery and five compared RFA with surgery (two studies had two or more comparisons with surgery). Study quality, evaluated through the six domains of risk of bias, was generally moderate for all included studies, however no study blinded participants, researchers and clinicians or outcome assessors. Also, nearly all included studies had other sources of bias. The overall quality of the evidence was moderate due to the variations in the reporting of results, which limited meaningful meta-analyses for the majority of proposed outcome measures. For the comparison UGFS versus surgery, the findings may have indicated no difference in the rate of recurrences in the surgical group when measured by clinicians, and no difference between the groups for symptomatic recurrence (odds ratio (OR) 1.74, 95% confidence interval (CI) 0.97 to 3.12; P = 0.06 and OR 1.28, 95% CI 0.66 to 2.49, respectively). Recanalisation and neovascularisation were only evaluated in a single study. Recanalisation at < 4 months had an OR of 0.66 (95% CI 0.20 to 2.12), recanalisation > 4 months an OR of 5.05 (95% CI 1.67 to 15.28) and for neovascularisation an OR of 0.05 (95% CI 0.00 to 0.94). There was no difference in the rate of technical failure between the two groups (OR 0.44, 95% CI 0.12 to 1.57). For EVLT versus surgery, there were no differences between the treatment groups for either clinician noted or symptomatic recurrence (OR 0.72, 95% CI 0.43 to 1.22; P = 0.22 and OR 0.87, 95% CI 0.47 to 1.62; P = 0.67, respectively). Both early and late recanalisation were no different between the two treatment groups (OR 1.05, 95% CI 0.09 to 12.77; P = 0.97 and OR 4.14, 95% CI 0.76 to 22.65; P = 0.10). Neovascularisation and technical failure were both statistically reduced in the laser treatment group (OR 0.05, 95% CI 0.01 to 0.22; P < 0.0001 and OR 0.29, 95% CI 0.14 to 0.60; P = 0.0009, respectively). Long-term (five-year) outcomes were evaluated in one study so no association could be derived,but it appeared that EVLT and surgery maintained similar findings. Comparing RFA versus surgery, there were no differences in clinician noted recurrence (OR 0.82, 95% CI 0.49 to 1.39; P = 0.47); symptomatic noted recurrence was only evaluated in a single study. There were also no differences between the treatment groups for recanalisation (early or late) (OR 0.68, 95% CI 0.01 to 81.18; P = 0.87 and OR 1.09, 95% CI 0.39 to 3.04; P = 0.87, respectively), neovascularisation (OR 0.31, 95% CI 0.06 to 1.65; P = 0.17) or technical failure (OR 0.82, 95% CI 0.07 to 10.10; P = 0.88).QoL scores, operative complications and pain were not amenable to meta-analysis, however quality of life generally increased similarly in all treatment groups and complications were generally low, especially major complications. Pain reporting varied greatly between the studies but in general pain was similar between the treatment groups.

AUTHORS' CONCLUSIONS

Currently available clinical trial evidence suggests that UGFS, EVLT and RFA are at least as effective as surgery in the treatment of great saphenous varicose veins. Due to large incompatibilities between trials and different time point measurements for outcomes, the evidence is lacking in robustness. Further randomised trials are needed, which should aim to report and analyse results in a congruent manner to facilitate future meta-analysis.

Endovenous laser with miniphlebectomy for treatment of varicose veins and effect of different levels of laser energy on recanalization. A single center experience

Varicose veins, associated with great saphenous vein (GSV) incompetence, are traditionally treated with conventional surgery. In recent years, minimally invasive alternatives to surgical treatment such as the endovenous laser ablation (EVLA) and radiofrequency (RF) ablation have been developed with promising results. Residual varicose veins following EVLA, regress untouched, or phlebectomy or foam sclerotherapy can be concomitantly performed. The aim of the present study was to investigate the safety and efficacy of EVLA with different levels of laser energy in patients with varicose veins secondary to saphenous vein reflux. From February 2006 to August 2011, 740 EVLA, usually with concomitant miniphlebectomies, were performed in 552 patients. A total of 665 GSV, 53 small saphenous veins (SSV), and 22 both GSV and SSV were treated with EVLA under duplex USG. At 84 patients, bilateral intervention is made. In addition, miniphlebectomy was performed in 540 patients. A duplex ultrasound (US) is performed to patients preoccupying chronic venous insufficiency (with visible varicose veins, ankle edema, skin changes, or ulcer). Saphenous vein incompetence was diagnosed with saphenofemoral, saphenopopliteal, or truncal vein reflux in response to manual compression and release with patient standing. The procedures were performed under local anesthesia with light sedation or spinal anesthesia. Endovenous 980-nm diode laser source was used at a continuous mode. The mean energy applied per length of GSV during the treatment was 77.5 ± 17.0 J (range 60-100 J/cm). An US evaluation was performed at first week of the procedure. Follow-up evaluation and duplex US scanning were performed at 1 and 6 months, and at 1 and 2 years to assess treatment efficacy and adverse reactions. Average follow-up period was 32 ± 4 months (3-55 months). There were one patient with infection and two patients with thrombus extension into the femoral vein after EVLA. Overall occlusion rate was 95%. No post-procedural deep venous thrombosis or pulmonary embolism occurred. Laser energy, less than 80 J/cm, was significantly associated with increased recanalization of saphenous vein, among the other energy levels. EVLA seems a good alternative to surgery by the application of energy of not less than 80 J/cm. It is both safe and effective. It is a well-tolerated procedure with rare and relatively minor complications.

Endovenous laser ablation (EVLA): a review of mechanisms, modeling outcomes, and issues for debate

Endovenous laser ablation (EVLA) is a commonly used and very effective minimally invasive therapy to manage leg varicosities. Yet, and despite a clinical history of 16 years, no international consensus on a best treatment protocol has been reached so far. Evidence presented in this paper supports the opinion that insufficient knowledge of the underlying physics amongst frequent users could explain this shortcoming. In this review, we will examine the possible modes of action of EVLA, hoping that better understanding of EVLA-related physics stimulates critical appraisal of claims made concerning the efficacy of EVLA devices, and may advance identifying a best possible treatment protocol. Finally, physical arguments are presented to debate on long-standing, but often unfounded, clinical opinions and habits. This includes issues such as (1) the importance of laser power versus the lack of clinical relevance of laser energy (Joule) as used in Joule per centimeter vein length, i.e., in linear endovenous energy density (LEED), and Joule per square centimeter vein wall area, (2) the predicted effectiveness of a higher power and faster pullback velocity, (3) the irrelevance of whether laser light is absorbed by hemoglobin or water, and (4) the effectiveness of reducing the vein diameter during EVLA therapy.

Thrombus formation using endovenous lasers: an in vitro experiment

OBJECTIVES

The purpose of these experiments was to simulate thrombus formation during endovenous laser closure by measuring coagulum formation of in vitro laser exposures in porcine blood and investigate the role of procedures and equipment in thrombus formation.

METHODS

Continuous wave 810, 940, 980, 1310 and 1470 nm lasers and microsecond pulsed wave 1064 nm Nd:YAG (neodymium-doped yttrium aluminium garnet), 1320 nm Nd:YAG and 2100 nm THC:YAG (thulium holmium chromium-doped yttrium aluminium garnet) lasers were tested with standard fibres with diameters of 365, 550 and 600 μm as well as two prototype modified tip fibres.

RESULTS

The results show that pulsed lasers with high-peak power densities form less coagulum. Fibre specifications were found not to influence coagulum formation, and prototype modified tip fibres designed to prevent contact between the fibre tip and the vein wall did not eliminate coagulum formation.

CONCLUSION

Microsecond-pulsed wave lasers with high-peak power densities may be a better choice to minimize soft thrombus formation during endovenous laser ablation treatments.

Endovenous laser ablation: a review of mechanisms of action

BACKGROUND

The aim of this article is to summarize and review the proposed theories on the laser action during endovenous ablation.

METHODS

Laser mechanics and laser-tissue interaction are summarized from articles found in literature. Several theories, like the "steam bubble theory," the "direct contact theory," the "heat pipe," and "direct light energy absorption" are discussed.

RESULTS

The laser light emitted intraluminally can be absorbed, scattered, or reflected. Reflection is negligible in the near-infrared spectrum. By combining absorption and scattering, the optical extinction of different wavelengths related to different biological tissues can be determined. The direct contact of the fiber tip and the vein wall may be a way of destroying the vein wall, but results in ulcerations and perforations of the vein wall. Avoiding this contact, and allowing direct light absorption into the vein wall, results in a more homogenous vein wall destruction. If the energy is mainly absorbed by the intraluminal blood, the laser fiber will act as a heat pipe. Histological studies show that a more circumferential vein wall destruction can be obtained when the vein is emptied of its intraluminal blood. The use of tumescent liquid reinforces spasm of the vein and protects the perivenous tissue.

CONCLUSION

Several factors play an important role in the mechanism of endovenous laser ablation. Direct energy absorption by the vein wall is the most efficient mechanism. It is important to empty the vein of its intraluminal blood and to inject tumescent liquid around the vein.

Endovenous ablation (radiofrequency and laser) and foam sclerotherapy versus conventional surgery for great saphenous vein varices

BACKGROUND

Minimally invasive techniques to treat great saphenous varicose veins include ultrasound-guided foam sclerotherapy (USGFS), radiofrequency ablation (RFA) and endovenous laser therapy (EVLT). Compared with conventional surgery (high ligation and stripping (HL/S)), proposed benefits include fewer complications, quicker return to work, improved quality of life (QoL) scores, reduced need for general anaesthesia and equivalent recurrence rates.

OBJECTIVES

To review available randomised controlled clinical trials (RCT) data comparing USGFS, RFA, EVLT to HL/S for the treatment of great saphenous varicose veins.

SEARCH STRATEGY

The Cochrane Peripheral Vascular Diseases (PVD) Group searched their Specialised Register (July 2010) and CENTRAL (The Cochrane Library 2010, Issue 3). In addition the authors performed a search of EMBASE (July 2010). Manufacturers of EVLT, RFA and sclerosant equipment were contacted for trial data.

SELECTION CRITERIA

All RCTs of EVLT, RFA, USGFS and HL/S were considered for inclusion. Primary outcomes were recurrent varicosities, recanalisation, neovascularisation, technical procedure failure or need for re-intervention, patient quality of life (QoL) scores and associated complications. Secondary outcomes were type of anaesthetic, procedure duration, hospital stay and cost.

DATA COLLECTION AND ANALYSIS

CN, RE, VB, PC, HB and GS independently reviewed, assessed and selected trials which met the inclusion criteria. CN and RE extracted data. The Cochrane Collaboration's tool for assessing risk of bias was used. CN contacted trial authors to clarify details.

MAIN RESULTS

Thirteen reports from five studies with a combined total of 450 patients were included. Rates of recanalisation were higher following EVLT compared with HL/S, both early (within four months) (5/149 versus 0/100; odds ratio (OR) 3.83, 95% confidence interval (CI) 0.45 to 32.64) and late recanalisation (after four months) (9/118 versus 1/80; OR 2.97 95% CI 0.52 to 16.98), although these results were not statistically significant. Technical failure rates favoured EVLT over HL/S (1/149 versus 6/100; OR 0.12, 95% CI 0.02 to 0.75). Recurrence following RFA showed no difference when compared with surgery. Recanalisation within four months was observed more frequently following RFA compared with HL/S although not statistically significant (4/105 versus 0/88; OR 7.86, 95% CI 0.41 to 151.28); after four months no difference was observed. Neovascularisation was observed more frequently following HL/S compared with RFA, but again this was not statistically significant (3/42 versus 8/51; OR 0.39, 95% CI 0.09 to 1.63). Technical failure was observed less frequently following RFA compared with HL/S although this was not statistically significant (2/106 versus 7/96; OR 0.48, 95% CI 0.01 to 34.25). No randomised clinical trials comparing HL/S versus USGFS met our study inclusion criteria. QoL scores and operative complications were not amenable to meta-analysis.

AUTHORS' CONCLUSIONS

Currently available clinical trial evidence suggests RFA and EVLT are at least as effective as surgery in the treatment of great saphenous varicose veins. There are insufficient data to comment on USGFS. Further randomised trials are needed. We should aim to report and analyse results in a congruent manner to facilitate future meta-analysis.

Endovenous laser treatment: a morphological study in an animal model

Objectives

The destruction induced during endovenous laser treatment (ELT) of the saphenous vein and the perivenous tissue in an animal model (goats) was analysed. Differences in vein wall destruction produced by two laser types, the 980 and 1500 nm diode lasers, were evaluated histologically.

Methods

In 14 goats, 28 lateral saphenous veins were treated with ELT. In 14 veins we used the 980 nm diode laser and in the remnant a 1500 nm laser. Postoperatively the veins were removed at different stages and sent for histological examination.

Results

Immediately removed veins after ELT show an uneven destruction of the vein wall. Veins harvested one week postoperatively show inflammatory tissue at their periphery. Two and three weeks postoperatively, organization is very extensive. In some cases, recanalization begins in a semi-lunar manner at the contralateral side of the laser hit. Veins treated with a 980 nm laser show deeper ulceration with more perivenous tissue destruction compared with veins treated with a 1500 nm diode laser.

Conclusions

The ELT of veins produces an unevenly distributed damage. The cell necrosis is far more extensive than expected. Uneven vein wall destruction can lead to recanalization. Using a 1500 nm laser correlates with less penetrating ulcerations and more circumferential damage.

Endovenous Laser Treatment of Saphenous Vein Reflux: How Much Energy Do We Need to Prevent Recanalizations?

The aim of this study was to report the results of high-energy endovenous laser treatment to measure the relationship between the fluence and the outcome in terms of recanalization. In 97 patients, 129 great saphenous veins were treated with endovenous laser treatment, using a 980-nm diode laser. Follow-up visits were done at 3 days, 1 month, and 6 months. The best results were noted 1 month postoperative, but at 6 months, control late recanalizations occured decreasing occlusion rate to 90.6%. Patients were divided into 2 groups according to the outcome (occlusion or recanalization) at 6 months, and statistical analysis was done. The authors found 52 J/cm2 mean fluence in the occlusion group and 43.7 J/cm2 in the nonocclusion group. This was a statistical significant difference ( P < .01). The occlusion rate on long term is fluence dependent. But recanalizations might occur even in these higher fluence treatment groups. A fluence of 52J/cm2 is advised.

Mathematical modeling of 980-nm and 1320-nm endovenous laser treatment

BACKGROUND AND OBJECTIVES

Endovenous laser treatment (ELT) has been proposed as an alternative in the treatment of reflux of the great saphenous vein (GSV) and small saphenous vein (SSV). Numerous studies have since demonstrated that this technique is both safe and efficacious. ELT was presented initially using diode lasers of 810 nm, 940 nm, and 980 nm. Recently, a 1,320-nm Nd:YAG laser was introduced for ELT. This study aims to provide mathematical modeling of ELT in order to compare 980 nm and 1,320 nm laser-induced damage of saphenous veins.

STUDY DESIGN/MATERIALS AND METHODS

The model is based on calculations describing light distribution using the diffusion approximation of the transport theory, the temperature rise using the bioheat equation, and the laser-induced injury using the Arrhenius damage model. The geometry to simulate ELT was based on a 2D model consisting of a cylindrically symmetric blood vessel including a vessel wall and surrounded by an infinite homogenous tissue. The mathematical model was implemented using the Macsyma-Pdease2D software (Macsyma, Inc., Arlington, MA). Calculations were performed so as to determine the damage induced in the intima tunica, the externa tunica and inside the peri-venous tissue for 3 mm and 5 mm vessels (considered after tumescent anesthesia) and different linear endovenous energy densities (LEED) usually reported in the literature.

RESULTS

Calculations were performed for two different vein diameters: 3 mm and 5 mm and with LEED typically reported in the literature. For 980 nm, LEED: 50 to 160 J/cm (CW mode, 2 mm/second pullback speed, power: 10 W to 32 W) and for 1,320 nm, LEED: 50 to 80 J/cm (pulsed mode, pulse duration 1.2 milliseconds, peak power: 135 W, repetition rate 30 Hz to 50 Hz).

DISCUSSION AND CONCLUSION

Numerical simulations are in agreement with LEED reported in clinical studies. Mathematical modeling shows clearly that 1,320 nm, with a better absorption by the vessel wall, requires less energy to achieve wall damage. In the 810-1,320-nm range, blood plays only a minor role. Consequently, the classification of these lasers into hemoglobin-specific laser wavelengths (810, 940, 980 nm) and water-specific laser wavelengths (1,320 nm) is inappropriate. In terms of closure rate, 980 nm and 1,320 nm can lead to similar results and, as reported by the literature, to similar side effects. This model should serve as a useful tool to simulate and better understand the mechanism of action of the ELT.

Mathematical modeling of endovenous laser treatment (ELT)

Background and objectives

Endovenous laser treatment (ELT) has been recently proposed as an alternative in the treatment of reflux of the Great Saphenous Vein (GSV) and Small Saphenous Vein (SSV). Successful ELT depends on the selection of optimal parameters required to achieve an optimal vein damage while avoiding side effects. Mathematical modeling of ELT could provide a better understanding of the ELT process and could determine the optimal dosage as a function of vein diameter.

Study design/materials and methods

The model is based on calculations describing the light distribution using the diffusion approximation of the transport theory, the temperature rise using the bioheat equation and the laser-induced injury using the Arrhenius damage model. The geometry to simulate ELT was based on a 2D model consisting of a cylindrically symmetric blood vessel including a vessel wall and surrounded by an infinite homogenous tissue. The mathematical model was implemented using the Macsyma-Pdease2D software (Macsyma Inc., Arlington, MA, USA). Damage to the vein wall for CW and single shot energy was calculated for 3 and 5 mm vein diameters. In pulsed mode, the pullback distance (3, 5 and 7 mm) was considered. For CW mode simulation, the pullback speed (1, 2, 3 mm/s) was the variable. The total dose was expressed as joules per centimeter in order to perform comparison to results already reported in clinical studies.

Results

In pulsed mode, for a 3 mm vein diameter, irrespective of the pullback distance (2, 5 or 7 mm), a minimum fluence of 15 J/cm is required to obtain a permanent damage of the intima. For a 5 mm vein diameter, 50 J/cm (15W-2s) is required. In continuous mode, for a 3 mm and 5 mm vein diameter, respectively 65 J/cm and 100 J/cm are required to obtain a permanent damage of the vessel wall. Finally, the use of different wavelengths (810 nm or 980 nm) played only a minor influence on these results.

Discussion and conclusion

The parameters determined by mathematical modeling are in agreement with those used in clinical practice. They confirm that thermal damage of the inner vein wall (tunica intima) is required to achieve the tissue alterations necessary in order to lead the vein to permanent occlusion. However, in order to obtain a high rate of success without adverse events, the knowledge of the vein diameter after tumescent anesthesia is recommended in order to use the optimal energy. As clearly demonstrated by our calculations, both pulsed and continuous mode operations of the laser can be efficient. An interesting observation in our model is that less amount of energy is required in pulsed mode than in continuous mode. Damaging the vein sequentially along its entire length may lead to permanent occlusion. However, the pulsed mode requires a very precise positioning of the fiber after each pullback and the duration of the treatment is much longer. For these reasons, continuous irradiation seems to be preferred by most clinicians. This model should serve as a useful tool to simulate and better understand the mechanism of action of the ELT