Re: “Modification of protocol with one extra drop of endovascular cyanoacrylate improved closure rates in incompetent great saphenous veins”—time to rethink the instructions for use for VenaSeal™?

Dear Sir,

We wish to congratulate Professor Chan et al. ¹ for his interesting paper neatly demonstrating that an extra drop of cyanoacrylate glue (CAG) delivered at the proximal great saphenous vein (GSV) may improve closure rates of refluxing GSV ≥ 8 mm diameter compared to those closed with normal IFU protocol using the VenaSeal™ device (Medtronic, Galway, Ireland). ¹ The authors however found that the GSV occlusion rates in the medium term (2 years) of those truncal veins ≥ 8 mm were still inferior to those GSV < 8 mm in diameter, using this modified protocol, although there was no increased incidence of endovenous glue-induced thrombosis (EGIT) at the sapheno-femoral junction (SFJ). Our group has previously described a similar double-dosing regimen to counter this re-opening effect in incompetent GSVs after we found early recurrences in our early experience using the same device. ² Our double-dosing regimen was slightly different from the one described here and followed the manufacturer’s IFU except that at the SFJ, rather than the usual 0.1 mL, 0.2 mL is injected immediately after the initial 1-cm pullback of the delivery catheter. Furthermore, where the GSV was focally dilated (>6 mm), at the level where significant branches came in and where incompetent perforators were located, double-dosing of CAG was injected with simultaneous gentle external massage using the ultrasound probe, to deliberately allow for glue dispersion into these incompetent venous reservoirs to cause occlusion. We found this to be highly efficacious (96% GSV occlusion rate at 6 months) with no increased number of adverse events such as thrombophlebitis or deep vein thrombosis. Obvious concerns using this double-dosing technique would be glue creeping toward the SFJ, but we observed 2/25 (8%) flush occlusions—a similar rate to this HK study, which were asymptomatic and managed conservatively. The uptake into surrounding varicosities, side branches and perforators had also been efficient. Do the authors think that potentially adding in more double-dosing (0.2 mL CAG) aliquots along the GSV, especially in thigh, could prevent recanalization events further especially for the larger truncal veins?

As the authors state, the precise mechanism for late recanalization of the GSV is unclear. The pattern of recurrence in Chan’s cohort, especially with the larger diameter veins > 8 mm, seems to be from the SFJ downwards. This begs the question about the role of the remnant stump length. Geier et al. studied 279 cases of groin recurrences after GSV stripping surgery and found that a long residual SFJ stump was present in two-thirds of cases, ³ which may cause recurrent varicosities by refluxing back pressure against the closed distal GSV and reflux migration via the other major superficial tributaries near the SFJ such as through the anterior accessory saphenous vein. One thought we have is that if the CAG does not oppose the two adjacent walls of the GSV completely during the initial curing process, especially in the bigger sized veins, there is a potential gap between the glue and the vein wall, which may open further and enlarge by the refluxing stump causing recanalization. Therefore, it may be critical to perform more aggressive CAG ablation between the terminal and pre-terminal valves, which are both thought to play an important role in the development of varicose veins (valvular incompetence theory) ⁴ and corresponds to the residual stump zone. We can therefore fully understand why the authors commenced their procedure only 4 cm distal to the SFJ compared to the device’s IFU of 5 cm to minimize this residual stump length. Perhaps they need to compress closer to the SFJ when they start the CAG embolization to allow more glue to dissipate closer to the SFJ, which is a technique employed using the Turkish glue devices for CAG ablation ⁵ ?