Use of a New Endovenous Laser Device: Results of the 1,500 nm Laser

Ultrasound and Photoacoustic Imaging for the Guidance of Laser Ablation Procedures

The accuracy and efficacy of laser ablation procedures depend on the accurate placement of the laser applicator within the diseased tissue, monitoring the real-time temperature during the ablation procedure, and mapping the extent of the ablated region. Ultrasound (US) imaging has been widely used to guide ablation procedures. While US imaging offers significant advantages for guiding ablation procedures, its limitations include low imaging contrast, angular dependency, and limited ability to monitor the temperature. Photoacoustic (PA) imaging is a relatively new imaging modality that inherits the advantages of US imaging and offers enhanced capabilities for laser-guided ablations, such as accurate, angle-independent tracking of ablation catheters, the potential for quantitative thermometry, and monitoring thermal lesion formation. This work provides an overview of ultrasound-guided procedures and how different US-related artifacts limit their utility, followed by introducing PA as complementary to US as a solution to address the existing limitations and improve ablation outcomes. Furthermore, we highlight the integration of PA-driven features into existing US-guided laser ablation systems, along with their limitations and future outlooks. Integrated US/PA-guided laser ablation procedures can lead to safer and more precise treatment outcomes.

Morphological changes of veins and perivenous tissues during endovenous laser coagulation using 2-μm laser radiation and various types of optical fibers

OBJECTIVE

To determine the morphological changes in veins and perivenous tissues after endovenous laser coagulation (EVLC) using laser radiation with a wavelength of 1910 nm and different types of fibers (bare tip and radial).

METHODS

The EVLC procedure was carried out on 22 surface veins of six sheep. The radiation source was a diode-pumped solid-state laser, which was based on a LiYF₄:Tm crystal and had an emission wavelength of 1910 nm and a maximum output power of 10 W. Two types of optical fibers were used: (1) bare tip and (2) radial or radial with two rings. Histological and morphometric methods were used, and the statistical digital data were analyzed.

RESULTS

The use of a linear endovenous energy density of 20 J/cm and optical bare fibers for veins with diameters of 3-4 mm resulted in a slit-shaped or wide venous wall perforation. A thermal effect was observed on the perivenous connective tissue (PVCT), which caused damage to its structures. Wide perforations were accompanied by complete destruction of the PVCT in the projection of the formed defect. The distance between the remaining vein wall fragment, located opposite to the perforation, and injured small vessels was 257.7 ± 23.6 μm. The radius of thermal damage increased to 2073.5 ± 8.0 μm near the vessel perforation. Using optical radial fibers for veins with diameters of 3.9 ± 0.5 mm did not lead to perforations. The destructive effect of the laser on small vessels of the PVCT extended to a distance of 425.7 ± 22.0 μm.

CONCLUSIONS

Analysis of thermal vessel damage in perivenous tissue after EVLC with bare-tip fiber shows that in the projection of a wide perforation, the damaged vessels of the PVCT are located at a large distance from the coagulated vein wall. On the opposite side of the perforation, the distance from the coagulated vein wall to the damaged vessels of the PVCT is significantly reduced because of the minimal output of laser radiation energy through the poorly damaged part of the wall. Using an optical radial fiber facilitates the application of a uniform distribution of thermal energy to the vein wall and damage to all its layers; at the same time, it minimizes the thermal energy that extends beyond the vein wall and damages the surrounding tissue.

CLINICAL RELEVANCE

The use of radiation with a wavelength of 1910 nm will make it possible to carry out endovenous laser coagulation of varicose veins at lower power values compared with radiation in the micron and one and a half micron regions of the spectrum. Understanding of morphological changes of veins and perivenous tissues after endovenous laser coagulation with 1910-nm laser radiation and different types of optical fibers (bare-tip, radial, radial 2ring) help predict possible complications and reduce their rate.

Systematic review on the incidence and management of endovenous heat-induced thrombosis following endovenous thermal ablation of the great saphenous vein

OBJECTIVE

A systematic review and meta-analysis was performed to determine the incidence of endovenous heat-induced thrombosis (EHIT) and evaluate its management after endovenous thermal ablation of the great saphenous vein (GSV).

METHODS

MEDLINE and Embase were searched for studies with at least 100 patients who underwent great saphenous vein endovenous thermal ablation and had duplex ultrasound follow-up within 30 days. Data were gathered on the incidence of thrombotic complications and on the management of cases of EHIT. The primary outcome for the meta-analysis was EHIT types 2 to 4 and secondary outcomes were deep venous thrombotic events (which we defined as types 2-4 EHIT plus deep vein thrombosis [DVT]), DVT, and pulmonary embolism (PE). Pooled proportions were calculated using random effects modelling.

RESULTS

We included 75 studies (23,265 patients). EHIT types 2 to 4 occurred in 1.27% of cases (95% confidence interval [CI], 0.74%-1.93%). Deep venous thrombotic events occurred in 1.59% (95% CI, 0.95%-2.4%). DVT occurred in 0.28% (95% CI, 0.18%-0.4%). Pulmonary embolism occurred in 0.11% (95% CI, 0.06%-0.18%). Of the 75 studies, 24 gave a description of the management strategy and outcomes for EHIT and there was inconsistency regarding its management. Asymmetrical funnel plots of studies that reported incidence of EHIT 2 to 4 and DVT suggest publication bias.

CONCLUSIONS

The recently published guidelines on EHIT from the Society for Vascular Surgery/American Venous Forum provide a framework to direct clinical decision-making. EHIT and other thrombotic complications occur infrequently and have a benign course.

Resultados de médio e longo prazo do tratamento endovenoso de varizes com laser de diodo em 1940 nm: análise crítica e considerações técnicas

Contexto

Desde a introdução do laser endovenoso para tratamento das varizes, há uma busca pelo comprimento de onda ideal, capaz de produzir o maior dano seletivo possível com maior segurança e menor incidência de efeitos adversos.

Objetivos

Avaliar os resultados de médio e longo prazo do laser de diodo de 1940 nm no tratamento de varizes, correlacionando os parâmetros utilizados com a durabilidade do desfecho anatômico.

Métodos

Revisão retrospectiva de pacientes diagnosticados com insuficiência venosa crônica em estágio clínico baseado em clínica, etiologia, anatomia e patofisiologia (CEAP) C2 a C6, submetidos ao tratamento termoablativo endovenoso de varizes tronculares, com laser com comprimento de onda em 1940 nm com fibra óptica de emissão radial, no período de abril de 2012 a julho de 2015. Uma revisão sistemática dos registros médicos eletrônicos foi realizada para obter dados demográficos e dados clínicos, incluindo dados de ultrassom dúplex, durante o período de seguimento pós-operatório.

Resultados

A média de idade dos pacientes foi de 53,3 anos; 37 eram mulheres (90,2%). O tempo médio de seguimento foi de 803 dias. O calibre médio das veias tratadas foi de 7,8 mm. A taxa de sucesso imediato foi de 100%, com densidade de energia endovenosa linear (linear endovenous energy density, LEED) média de 45,3 J/cm. A taxa de sucesso tardio foi de 95,1%, com duas recanalizações por volta de 12 meses pós-ablação. Não houve nenhuma recanalização nas veias tratadas com LEED superior a 30 J/cm.

Conclusões

O laser 1940 nm mostrou-se seguro e efetivo, em médio e longo prazo, para os parâmetros propostos, em segmentos venosos com até 10 mm de diâmetro.

Comparison of Endovenous Laser and Radiofrequency Ablation in Treating Varices in the Same Patient

Introduction: To compare endovenous laser ablation (EVLA) and radiofrequency ablation (RFA) in different legs in the same individual in patients with venous insufficiency. Methods: Sixty patients with bilateral saphenous vein insufficiency were included. EVLA or RFA was applied to one of the patient's legs and RFA or EVLA to the other leg. Results: EVLA and RFA complications were hyperemia at 20.7% and 31.0%, ecchymosis at 31.0% and 51.7% and edema at 27.6% and 65.5%, respectively. The rate of recanalization was 6.8% in the RFA group. No recanalization was observed in EVLA group. The level of patients satisfied with EVLA was 51.7%, compared to 31.0% for RFA, while 17.2% of patients were satisfied with both procedures. Times to return to daily activity were 0.9 days in the EVLA group and 1.3 days in the RFA group. Conclusion: EVLA procedure may be superior to RFA in certain respects.

Factors affecting optimal linear endovenous energy density for endovenous laser ablation in incompetent lower limb truncal veins – A review of the clinical evidence

Objectives

The objective is to identify the factors that affect the optimal linear endovenous energy density (LEED) to ablate incompetent truncal veins.

Methods

We performed a literature review of clinical studies, which reported truncal vein ablation rates and LEED. A PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) flow diagram documents the search strategy. We analysed 13 clinical papers which fulfilled the criteria to be able to compare results of great saphenous vein occlusion as defined by venous duplex ultrasound, with the LEED used in the treatment.

Results

Evidence suggests that the optimal LEED for endovenous laser ablation of the great saphenous vein is >80 J/cm and <100 J/cm in terms of optimal closure rates with minimal side-effects and complications. Longer wavelengths targeting water might have a lower optimal LEED. A LEED <60 J/cm has reduced efficacy regardless of wavelength. The optimal LEED may vary with vein diameter and may be reduced by using specially shaped fibre tips. Laser delivery technique and type as well as the duration time of energy delivery appear to play a role in determining LEED.

Conclusion

The optimal LEED to ablate an incompetent great saphenous vein appears to be >80 J/cm and <95 J/cm based on current evidence for shorter wavelength lasers. There is evidence that longer wavelength lasers may be effective at LEEDs of <85 J/cm.

Comparison of Endovenous Laser and Radiofrequency Ablation in Treating Varicose Veins in the Same Patient

Purpose:

To compare endovenous laser ablation (EVLA) and radiofrequency venous ablation (RFA) in different legs in the same patients with venous insufficiency.

Methods:

Sixty patients with bilateral saphenous vein insufficiency were included. Endovenous laser ablation or RFA was applied to one of the patient’s legs and the remaining procedure, RFA or EVLA, to the other leg.

Results:

Minor complications in EVLA and RFA were hyperemia at 20.7% and 31.0%, ecchymosis at 31.0% and 51.7% and edema at 27.6% and 65.5%, respectively. The rate of recanalization was 6.8% in the RFA group. No recanalization was observed in the EVLA group. The level of patients satisfied with EVLA was 51.7%, compared to 31.0% for RFA, while 17.2% of patients were satisfied with both the procedures. Times to return to daily activity were 0.9 days in the EVLA group and 1.3 days in the RFA group.

Conclusion:

The EVLA procedure may be superior to RFA in certain respects.

The effect of wavelength on endothermal heat-induced thrombosis incidence after endovenous laser ablation

OBJECTIVE

We hypothesized that the incidence of endothermal heat-induced thrombosis (EHIT) depends on the laser wavelength used in endovenous laser ablation (EVLA) of the saphenous veins.

METHODS

We identified patients undergoing EVLA in our office from 2005 to 2014 with an 810-nm (hemoglobin-specific) or 1470-nm (water-specific) laser. We reviewed the records for age, sex, body mass index, Clinical, Etiologic, Anatomic, and Pathophysiologic (CEAP) class, vein diameter, vein(s) treated, adjunctive phlebectomy, energy delivered, laser pullback times, and EHIT (closure level ≥3) development. The Fisher exact test and Pearson χ(2) test were used to evaluate the association between EHIT and the categoric variables. Logistic regression was used to evaluate the relationship between EHIT and the continuous variables.

RESULTS

There were 1439 veins ablated in 1109 patients (769 female, 340 male). The great saphenous vein (GSV) was treated in 1332, the small saphenous vein (SSV) in 78, and both in 29 (22 procedures on accessory veins were excluded). The CEAP C class for these patients was 1 in 0, 2 in 616, 3 in 522, 4 in 150, 5 in 51, and 6 in 98, and was not recorded in 2. EHIT occurred in 76 cases (5.28%), in 73 after GSV ablation and in three after SSV ablation. The 810-nm laser was used in 1144 procedures, and EHIT developed in 69 patients (6.0%). The 1470-nm laser was used in 295 procedures, with EHIT developing in seven patients (2.4%; P = .0122 by Fisher exact test). The average energy delivered to the EHIT group (3517 ± 1998.1 J) was higher than for the non-EHIT group (2825.1 ± 1491.2 J; P = .0002). The average vein diameter was larger in the EHIT group (9.3 ± 3.8 mm) than in the non-EHIT group (7.2 ± 3.3 mm; P = .0001). EHIT occurred in 59 of 837 cases (6.6%) undergoing simultaneous stab phlebectomy compared with 17 of 525 cases (3.1%) undergoing only EVLA (P = .0049). Statistical analysis confirmed the association between EHIT and CEAP class was significant (P = .0001). No differences were seen for age, body mass index, sex, combined bilateral, and multiple or simultaneous GSV and SSV ablations between the two groups. A multivariate analysis confirmed that CEAP class, vein diameter, adjunctive phlebectomy, and laser wavelength were indeed risk factors for post-EVLA EHIT and that energy delivered and pullback time were not.

CONCLUSIONS

Water-specific laser fiber wavelength (1470 nm) reduces the risk of EHIT compared with a hemoglobin-specific wavelength (810 nm). CEAP class, simultaneous phlebectomy, and vein diameter >7.5 mm are associated with increased risk of EHIT after EVLA.

Laser; best practice techniques and evidence

Laser ablation involves the delivery of laser light through a glass fibre placed into the lumen of a refluxing vein. This energy is converted into heat inducing a permanent, non-thrombotic occlusion. This highly effective and safe approach has significant advantages over traditional surgical treatment and has driven the endovenous revolution in the management of varicose veins. This chapter will explore the mechanism of action, present the evidence of laser' clinical and cost effectiveness, and analyse specific and generic aspects of laser ablation technique.

Five-year results from the prospective European multicentre cohort study on radiofrequency segmental thermal ablation for incompetent great saphenous veins

Background

This was a prospective study of radiofrequency segmental thermal ablation (RFA) for the treatment of incompetent varicose great saphenous veins (GSVs). The present report describes long-term follow-up at 5 years.

Methods

The 5-year follow-up of this multicentre European study included assessment of the Venous Clinical Severity Score (VCSS), and GSV occlusion and reflux on duplex imaging.

Results

A total of 225 patients had 295 GSVs treated by RFA, achieving an initial vein occlusion rate of 100 per cent. With 80·0 per cent compliance, Kaplan–Meier analyses showed a GSV occlusion rate of 91·9 per cent and a reflux-free rate of 94·9 per cent at 5 years. Among the 15 GSVs noted with reflux during follow-up, only three showed full recanalization of the GSV at 1 week, 6 months and 3 years. Of the 12 legs with partial recanalization, reflux originated at the saphenofemoral junction in ten, with a mean length of the patent segment of 5·8 (range 3·2–10) cm; only six patients were symptomatic. Mean(s.d.) VCSS scores improved from 3·9(2·1) at baseline to 0·6(1·2), 0·9(1·3) and 1·3(1·7) at 1, 3 and 5 years.

Conclusion

At 5 years RFA proved to be an efficient endovenous treatment for incompetent GSVs in terms of sustained clinical and anatomical success for the vast majority of treated patients.

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.

Numerical simulation of endovenous laser treatment of the incompetent great saphenous vein with external air cooling

Endovenous laser treatment (ELT) has been proposed as an alternative in the treatment of reflux of the great saphenous vein. Before the procedure, peri-saphenous subcutaneous tumescent saline solution infiltration is usually performed. However, diffusion of this tumescent fluid is rapidly observed and can potentially reduce the efficacy as a heat sink. External skin cooling with cold air was proposed as an alternative solution. The objective of this study is to compare endovenous laser treatment without and with air cooling by realistic numerical simulations. An optical-thermal damage model was formulated and implemented using finite element modeling. The general model simulated light distribution using the diffusion approximation of the transport theory, temperature rise using the bioheat equation, and laser-induced injury using the Arrhenius damage model. Parameters, used in clinical procedures, were considered: power, 15 W; pulse duration, 1 s; fiber pull back, 3-mm increments every second; cold air applied in continuous mode during ELT; and no tumescent anesthesia. Simulations were performed for vein locations at 5, 10, and 15 mm in depth, with and without air cooling. For a vein located at 15 mm in depth, no significant difference was observed with and without cooling. For a vein located at 10 mm in depth, surface temperature increase up to 45 °C is observed without cooling. For a vein located at 5 mm, without cooling, temperature increase leads to irreversible damage of dermis and epidermis. Conversely, with air cooling, surface temperature reaches a maximum of 38 °C in accordance with recordings performed on patients. ELT of the incompetent great saphenous vein with external air cooling system is a promising therapy technique. Use of cold air on the skin continuously flowing in the area of laser shot decreased significantly the heat extent and the thermal damage in the perivenous tissues and the skin.

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.

Varicose vein: current management

The continued advancement of RFA and EVLS technology should provide for an increased safety profile and lasting efficacy for treating the major saphenous veins. The challenge lies in determining what type of patient comorbidities and anatomic variability result in higher recurrences after endothermal varicose vein treatment so that one can modify the choice of treatment appropriately. Further standardization of the FS technique may allow for its wider use in treating truncal varicosities. The powered phlebectomy system seems to be suited for isolated branch varicosities, but the sequelae of pain and ecchymosis may prevent it from becoming a mainstream treatment with stab phlebectomy and sclerotherapy as alternatives.