AVMs are congenital vascular malformations developed by defects of arterial and venous origins that result in direct communications between vessels of different sizes or primitive reticular networks of dysplastic vessels that have failed to mature into “capillary” vessels called “nidus” (Lee et al. 2013). AVMs have angiographic classification, proposed by Do et al. (Cho et al. 2006; Ko et al. 2019). According to this, our case was AVM type IIIb, which had multiple shunts between the arterioles and venules with dilated fistulae. Direct puncturing of the dilated fistula and injecting ethanol have been proven to be effective, and induced fewer skin complications than transarterial injection (Park et al. 2019). During the last sessions, we performed transarterial and direct puncture alcohol injections. However, these did not work due to the very high velocity of AMVs. Thus, we planned to use a transvenous approach and perform embolization using balloon-occluded glue injection to slow down the velocity and maximize the efficiency of alcohol.
Balloon-occluded glue injection, called the B-glue technique, was introduced by Hamaguchi et al. (Hamaguchi et al. 2013, 2015). This demonstrated many advantages over the flow-dependent technique. It can demonstrate better control of embolus range and less reflux. Moreover, it can also help prevent proximal embolization and distal migration. That said, it has a greater pullback resistance than the flow-dependent technique when reflux occurs due to a larger adhesion area than the usual microcatheter. Furthermore, it is important to remove the microballoon catheter immediately upon reflux detection. In our case, it was performed in venous system and we had no choice but to wait for the polymerization of glue to prevent migration to systemic blood flow.
Several studies have been reported on the prevention of glue reflux and balloon adhesion during the B-glue technique. Mine et al. reported that glue injection via distally advanced microcatheter inserted in the inflated microballoon catheter decreased the risk of glue adhesion to the balloon surface compared with direct injection via a microballoon catheter (Mine et al. 2020). Moreover, Kawai et al. reported that adding ethanol to glue and iodized oil mixture can render microcatheter adhesion negligible. They assumed that rapid completion of N-butyl cyanoacrylate (NBCA) sclerosis by adding ethanol was the cause of the minimal adhesion of NBCA to the catheter (Kawai et al. 2012). However, no reports have been published describing rescue method after adhesion of balloon catheters.
We were able to remove the stuck and broken pieces of the microballoon catheter by filling the guiding catheter with glue to anchor the pieces and pulling them all out together. This technique can be very useful when any object to be removed is inside the catheter or sheath. These conditions can include broken microcatheter within larger catheter and unwillingly deployed detachable or pushable coils that do not entirely come out of the catheter. It is very important to know the internal volume of catheter to prevent overflow of glue while performing this rescue technique.
This technique may also be helpful in removing stuck microcatheters by glue even if they are not broken. In our case, when the microballoon was stuck to the vein wall, we pulled hard on the distal portion of the catheter. However, rather than pulling off, the catheter broke inside the guiding catheter. When we pulled it after filling the guiding catheter with glue, the stuck microballoon fell off. This is probably due to the effect of pulling it from the far proximal of the stuck catheter. It would be more efficient to pull out the catheter adjacent to the adhesion site rather than distal part. In case of unbroken microcatheter stuck by glue, pulling it after advancing outer catheter near the attachment site and making glue casting into outer catheter can be more helpful.
