A description of the ‘smile sign’ and multi-pass technique for endovenous laser ablation of large diameter great saphenous veins

Abstract

Aims

To report on great saphenous vein diameter distribution of patients undergoing endovenous laser ablation for lower limb varicose veins and the ablation technique for large diameter veins.

Methods

We collected retrospective data of 1929 (943 left leg and 986 right leg) clinically incompetent great saphenous vein diameters treated with endovenous laser ablation over five years and six months. The technical success of procedure, complications and occlusion rate at short-term follow-up are reported. Upon compression, larger diameter veins may constrict asymmetrically rather than concentrically around the laser fibre (the ‘smile sign’), requiring multiple passes of the laser into each dilated segment to achieve complete ablation.

Results

Of 1929 great saphenous veins, 334 (17.31%) had a diameter equal to or over 15 mm, which has been recommended as the upper limit for endovenous laser ablation by some clinicians. All were successfully treated and occluded upon short-term follow-up.

Conclusion

We suggest that incompetent great saphenous veins that need treatment can always be treated with endovenous laser ablation, and open surgery should never be recommended on vein diameter alone.

Keywords

Duplex ultrasound endovenous laser ablation great saphenous vein saphenofemoral junction thermal ablation

Introduction

Within the last two decades, widespread availability of duplex ultrasonography has enabled vast progression within the field of venous surgery. Traditionally, varicose vein surgery resulted in a significant morbidity, as the underlying venous reflux was treated with open surgical procedures that coincide with high recurrence and poor long-term success rates.^1–3

The current trend of catheter-based endovenous thermal ablation initially appeared with radiofrequency ablation in the late 1990s and was joined soon afterwards with endovenous laser ablation (EVLA). The development of minimally invasive endovenous thermal ablation techniques has largely overcome the traditional surgical limitations. Thermally induced fibrotic occlusion has been shown to successfully eliminate venous reflux in mid- to long-term research.^4–6 Incidentally, in 2013, the National Institute of Health and Care Excellence recommended ‘endothermal ablation’ as the optimal treatment procedure for truncal vein reflux.⁷

However, traditional surgical techniques remain popular with many surgeons, and in particular, the use of endovenous or open surgical techniques in larger truncal veins with a diameter over 15 mm remains controversial. Some practitioners have classified veins that are highly tortuous or with a large diameter as unsuitable for thermal ablation and, in some instances, consider open-surgery to be a superior treatment option.^8–10

The objective of this study was to report our experience using EVLA to treat incompetent great saphenous vein (GSV) of any diameter. In this report, we have shown the distribution of GSV diameters that have been successfully treated with EVLA by one consultant vascular surgeon over five years and six months. We have described the endovenous technique for treating incompetent veins with a large diameter, particularly those that do not contract concentrically onto the endovenous laser catheter (the ‘smile sign’).

Patients and methods

Data collection

Using a prospectively completed database, we obtained measurements of incompetent venous diameter from the GSV of all procedures performed by one vascular surgeon from our unit (BAP) from March 2011 to September 2016, which equated to 1929 truncal veins (943/1929 left leg and 986/1929 right leg). All patients with incompetent GSVs were treated with EVLA, and no patient was excluded from this treatment. All veins treated with a diameter under 4 mm were excluded from this study.

GSV measurement was obtained using a duplex ultrasound scan, with the patient standing upright, at room temperature and bearing weight on the leg that was not being scanned.

We did not require ethics for this study, as it is not required for reporting audit figures. Verbal informed consent was obtained from all patients.

Surgical technique

Access to the GSV was made using the Seldinger technique with the patient in a head up position to maximally dilate the vein. A guide wire was percutaneously inserted into the distal GSV and advanced towards the saphenofemoral junction (SFJ). A cannula on an introducer was inserted into the vein over the guidewire. The introducer and wire were removed, and the EVLA device passed up the vein under ultrasound control. During this study, two different EVLA devices were used: the radial firing 1470 nm ELVeS fibre (Biolitec, Jena, Germany) and the forward firing NeverTouch Direct 1470 nm Jacket Tipped Fibre (AngioDynamics, Queensbury, NY).

The patient was moved into a head down position to help contract the vein onto the device and tumescence was administered around the outside of the vein and within the saphenous fascia, protecting the surrounding tissue. Appropriate laser fibre placement near the SFJ was visualised under ultrasound. For the radial firing laser, the tip was placed just distal to the junction of the inferior epigastric vein and GSV. For the forward firing laser, the tip was placed near this point and external pressure was applied via the ultrasound probe, compressing the vein and attempting to trap the thermal energy as represented by the steam bubbles visualised on ultrasound (the ‘Bubble Trap Technique’).¹¹ Subsequently, ablation was performed with both devices using a power of 10 W, and pullback of 6 to 9 cm/s giving a linear endovenous energy density (LEED) of 60 to 90 J/s. Pullback speed and, as the power was kept at 10 W, hence LEED were selected on vein diameter and vein wall thickness.

Generally, sufficient tumescence together with the application of external pressure with the ultrasound probe will concentrically compress the vein around the laser fibre; therefore continuous pullback during procedure will successfully ablate the entire vein wall. Veins with a wide lumen diameter may constrict asymmetrically on compression with the probe, forming adjacent bulges rather than a circular contraction (Figure 1) and also under tumescence around the laser fibre (Figure 4(b)). We call this the ‘smile sign’. This compression rather than constriction reduces the surface area of the vein wall adjacent to the laser tip. Consequentially, in such a vein, only part of the wall can be adequately treated in one passage of the endovenous laser tip. It is important to consider that the appearance of the ‘smile sign’ is not synonymous with a particular vein diameter measurement, hence ultrasound evaluation is essential. However, the presence of the ‘smile sign’ shows that the vein has not constricted concentrically around the endovenous device suggesting more than one pass is necessary to distribute heat to the whole vein wall.

Figure 1.

Compression of a large diameter vein – the ‘smile sign’.

Therefore, in venous segments that do not concentrically constrict and which compress in the ‘smile sign’, the EVLA device is pulled back once, causing constriction of a certain area of vein wall but leaving a lumen formed by currently untreated vein wall. Once the segment has been traversed, the fibre is passed gently back up through the patent part of the vein, and it tracks through the area of untreated vein wall and patent lumen. A second pass is then performed, heating more of the vein wall and constricting more of the lumen. This process is repeated as many times as is required to obliterate the vein lumen and hence treat the whole of the vein wall. We have never had a perforation when performing this technique in this way. Multiple passes may be required for a very large vein. The multi-pass technique aims to expose the total circumferential vein wall to adequate thermal energy to enable successful ablation of such dilated segments.

When administering the multi-pass technique, ultrasound evaluation of the dilated vein section being treated is essential. When the laser is passed into a vein, and is activated, contraction of that section can be visualised. Enough passes have been made when total circumferential vein contraction can be observed. This will ensure that the entire vein wall has been exposed to adequate laser energy.

The number of passes required for complete ablation of each wide diameter GSV varies. The diameter of the vein is an important determining factor. However, there is no linear relationship between the number of passes and the diameter. The number of passes also relies on the responsiveness of the vein to contraction under treatment. The number of passes we have used for treating incompetent vein segments has varied from two to eight.

Follow-up

The data that we gathered about GSV diameters that have been treated with EVLA were obtained prospectively. The retrospective database consisted of the information we obtained upon the normal treatment procedure. We did not actively follow-up on these patients over time for the purpose of this study. Therefore, the follow-up data obtained were also retrospective, and for most patients, this was at eight weeks post procedure when they returned for follow-up ultrasound guided foam sclerotherapy. Upon this follow-up, a specialist clinical vascular scientist would perform a duplex ultrasound scan to assess the treated vein. EVLA is defined as successful when no blood flow can be observed on a duplex ultrasound scan, but also when fibrotic rather than thrombotic occlusion is identified.

Results

Venous diameters ranged from 4 to 42 mm in the left leg and 4 to 33 mm in the right leg, as shown in Figures 2 and 3, respectively. Mean GSV diameter was 9.68 mm for the left leg and 9.78 mm for the right leg. Both legs had a median value of 8 mm.

Figure 2.

A graph showing the distribution of diameters of the left GSVs.

Figure 3.

A graph showing the distribution of diameters of the right GSVs.

All patients returned approximately eight weeks after EVLA for follow-up. Upon duplex ultrasound examination, no colour flow was observed, and successful complete fibrotic occlusion of the entire length of the treated GSV was confirmed in all cases.

Of this cohort, 17.31% (334/1929 of all GSVs, made up of 167/943 (17.70%) left GSV and 167/986 (16.94%) right GSV) had a diameter measurement of 15 mm or over upon initial examination. All veins were successfully treated with EVLA and upon a short-term follow-up, veins of all diameters – 100% of treated veins – were seen to be successfully occluded. There was no difference in the surgical success rates between GSVs of different diameter. So overall in our experience, we have found that 100% of incompetent GSVs are eligible for EVLA, regardless of diameter, with proven short-term success (Figure 4).

Figure 4.

Duplex ultrasound imaging of a large GSV (measured 3.59 cm on screen) (a), with the addition of tumescent anaesthesia (b) and post-EVLA (c).

In all the cases, we retrospectively reviewed, incidence of endovenous heat induced thrombosis (EHIT) and deep vein thrombosis (DVT) have been negligible. We report no incidence of EHIT and three cases of DVT over the 1929 GSVs treated (0.16%). It is important to note that no DVT case was persistent and resolved with compression and/or anticoagulants.

Discussion

Thermal ablation has been increasingly used to treat varicose veins over the past two decades. The superiority of endovenous thermal ablation over high saphenous ligation and stripping for the treatment of truncal venous reflux has been highlighted by some long-term research. One study has shown revascularisation rates to be as high as 82% five to eight years after open surgery, caused by the formation of a haematoma within the strip tract.^2,3 Comparatively, endovenous thermal ablation, if done properly, will induce fibrotic occlusion with transmural vein wall cell death, which is reflected by one reported success rate of 86% seven-year post-EVLA.⁵

Understandably, there appears to be no debate regarding the surgical preference of EVLA for veins with a diameter less than 8 mm. However, thermal ablation has not yet been accepted as standardised treatment protocol for veins over 15 mm. Some research has suggested that using EVLA to treat incompetent veins with an approximate diameter measurement between or over 8 to 15 mm is unsuitable, and, in some instances, open-surgery has even been recommended as preferential.^8–10,12,13

In this report, 17.31% of a clinical cohort had a vein diameter measuring 15 mm or over and we did not observe any difference in the short-term surgical outcome in those with a smaller diameter. This equates to 334 veins that would have otherwise been recommended for suboptimal open surgical intervention.

There appears to be two major underlying reasons why open surgery has occasionally been recommended for larger veins rather than endovenous thermal ablation: the risk of thrombus formation or recanalisation in an incompletely ablated vein lumen. A thrombus may form within the terminal GSV, or propagate into the deep venous system, causing EHIT and DVT respectively.^12,14 DVT has been noted as a relatively common occurrence following varicose vein surgery, but the risk of EHIT emerged following the widespread use of thermal ablation; research has suggested this risk to be high at the SFJ.^12,15 Consequentially, the proximal GSV diameter has been regarded as an important factor when considering the eligibility for EVLA; Starodubtsev et al.⁹ reported preferential use of open surgery when the proximal diameter exceeded 15 mm. Regardless, at our unit, we see minimal incidence of either EHIT or DVT, which has been reported previously.¹⁴ To avoid the propagation of thermal energy into the femoral vein when using a forward firing laser fibre, we use the Bubble Trap technique.¹¹ This, together with sufficient tumescent anaesthesia to appropriately collapse the vein around the laser fibre and the application of our multi-pass laser pass technique should elicit a desirable and safe outcome in veins of all sizes.

As described above, for appropriate treatment of veins with a large diameter, the entire vein wall surface area must be exposed to adequate thermal energy from the endovenous laser. Inadequate thermal treatment may result in endothelial damage without contraction of the vein wall, allowing thrombus formation and a thrombotic rather than a fibrotic occlusion. Intraluminal thrombus with living media surrounding it can result in subsequent recanalisation of the truncal vein and recurrent varicose vein formation. Such recanalisation is commonly seen after thrombophlebitis. Research has reported an enhanced risk of recanalisation or revascularisation and less extensive thermal penetration in veins, with a diameter measuring over 8.5 mm and 10 mm, respectively.^10,16 As we suggested in 2004, it appears that transmural death of the vein wall is required to ensure permanent fibrotic closure of the vein wall.¹⁷ Therefore, it is important to consider that laser energy has to both be incident on the inner surface of the vein wall and to conduct adequately across the whole of the vein wall to get the desired fibrotic closure. Therefore, when poor results are obtained following EVLA of large veins, it is probably because adequate circumferential thermal penetration was not achieved. One cause of this might be due to a failure to expose the entire inner surface area of the vein wall to the laser energy.

This argument also extends to laser power. Many practitioners consider that larger veins require the application of a higher laser energy.^9,13,18 However, blasting more energy into only one part of the vein wall or indeed simply into a large vein lumen where it might not be adequately conducted to the vein wall to be treated may not elicit more desirable outcome. When a vein has a large diameter, this measurement does not necessarily reflect the vein wall thickness. Therefore, by using the multi-pass approach in this large section of vein, we can ensure that we are increasing the chances of the whole of the inner surface of the vein to be treated, and that the thermal distribution within the wall is adequate for successful ablation.

We acknowledge that there are limitations in this study as retrospective data were obtained prospectively. Therefore, at the time of treatment, we did not think that we would be using these cases for this evaluation, and so we did not actively conduct long-term follow-up, which would have been a useful addition to the study. It will be interesting to evaluate the long-term outcome of performing the multi-pass technique in further research in the future and compare it to the long-term success rate obtained with other endovenous laser methods.

In conclusion, larger veins or dilated segments of veins that show the ‘smile sign’ upon compression can be treated with EVLA with successful short-term occlusion using the multi-pass technique. Therefore, we suggest that vein diameter alone should not be considered an exclusion factor for treatment by EVLA and, using this approach, we have found no patient should receive open surgery for an incompetent GSV.

Footnotes

Declaration of Conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Ethical approval

Not required for reporting audit figures.

Guarantor

Professor Mark Whiteley.

Contributorship

Emma B Dabbs – Writing the manuscript, data collection, analysis and interpretation.

Laurensius E Mainsiouw – Writing the manuscript and data collection.

Judith M Holdstock – Conception and design, data collection, analysis and interpretation.

Barrie A Price – Conception and design, data collection, analysis and interpretation.

Mark S Whiteley – Conception and design, writing the manuscript, analysis and interpretation, and critical revision of the manuscript.

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