Dislodged stent after stent reverse controlled antegrade and retrograde subintimal tracking (CART) — Is stent reverse CART a necessary tool or an unnecessary evil?

Abstract

We report a case of stent reverse controlled antegrade and retrograde subintimal tracking (CART) in left anterior descending artery (LAD) chronic total occlusion. Reverse CART is the method used to make a connection between the retrograde wire and the antegrade true lumen by using a balloon to dilate the antegrade space and pushing the retrograde wire into this space. We successfully crossed the septal channel from right coronary to the LAD, and proceeded to reverse CART, which was unsuccessful. After demonstrating that both the retrograde and antegrade wires were in the same subintimal space by intravascular ultrasound (IVUS), we placed the distal stent edge at the connection point of the wires and deployed the stent. We could easily wire the stent lumen with the retrograde conquest 9 g wire. Afterwards we tried to push the retrograde corsair microcatheter through the CTO and into the antegrade guiding, but unfortunately, the retrograde corsair could not pass into the antegrade guiding and was stuck just outside the antegrade guiding ostium. At this point IVUS showed that the stent had been dislodged from the LAD and pushed into the aorta just outside the left main by the retrograde corsair because the retrograde wire passed into the stent lumen through a distal side strut opening and not through the true distal end of the stent. Due to unstable hemodynamics we had to remove the retrograde system and this led to stent embolism. The case illustrates stent dislodgement after stent reverse CART and stresses the importance of using IVUS to check fully the retrograde wire path before pushing the corsair. We discuss the role of stent reverse CART in the contemporary reverse CART era and conclude that it should be relegated to the very last resort after trying transit balloon technique. We conclude that stent reverse CART is mostly an unnecessary evil.

<Learning objective: The case illustrates the dangers of stent reverse controlled antegrade and retrograde subintimal tracking (CART) and discusses the alternative options to stent reverse CART, as well as how to perform stent reverse CART safely with the use of intravascular ultrasound both before stenting and after stenting to ensure correct wire passage through the stent.>

Introduction

Stent reverse controlled antegrade and retrograde subintimal tracking (CART) has been used as a method to overcome the problem of reverse CART. Stenting the chronic total occlusion (CTO) segment on the antegrade wire creates the biggest possible sustained lumen as a target for the retrograde wire. It prevents the recoil of tissue after ballooning and removes proximal vessel dissection flaps that can trap the retrograde wire. However, stent reverse CART is rarely necessary in the contemporary reverse CART era. Joyal et al. [1] in their landmark review of retrograde techniques describes stent reverse CART, but they state their preference to use guideline reverse CART instead. In the Asia Pacific CTO Club (APCTO) retrograde algorithm [2], stent reverse CART is placed as a cautioned last resort option, when there is connection between antegrade and retrograde wires shown on intravascular ultrasound (IVUS). There are of course other ways to create the biggest possible antegrade space for retrograde wire puncture without resorting to stent reverse CART, for example, the previously described technique of transit balloon by Wu et al. [3]. Since stent reverse CART is so rarely used, complications arising in stent reverse CART cases are extremely rare. We describe a case of dislodged stent by retrograde corsair after stent reverse CART and discuss the issue of whether stent reverse CART is a necessary tool or an unnecessary evil.

Case report

A 47-year-old man with past history of type II diabetes, hypertension, and hypercholesterolemia, presented with effort angina in 2015. He underwent an exercise tolerance test, which was positive. A coronary angiogram showed CTO to the right coronary artery (RCA) (Fig. 1a) and the left anterior descending (LAD) arteries (Fig. 1b). The circumflex artery had no significant stenosis. Antegrade CTO percutaneous coronary intervention (PCI) was successfully performed on the RCA with drug-eluting stent implantation, but the antegrade attempt to the LAD was unsuccessful, and he was referred to our CTO proctorship program.

Fig. 1.

(a) Right coronary artery chronic total occlusion (CTO). (b) Septal channel in left anterior descending artery CTO. (c) Posterior descending artery septal collateral channel. (d) Successful septal crossing. (e) Retrograde wires go into septal. (f) Retrograde Ultimate Bros 3 wire in subinitimal proximally.

Single femoral access with a EBU 3.5 8 French guiding (Medtronic, Minneapolis, MN, USA) for ipsilateral septal to septal collateral (Fig. 1b) was attempted in view of the decent size of the channel, but we were unable to cross the channel despite using Sion and XTR wires (Asahi Intecc, Nagoya, Aichi, Japan). Therefore a second femoral access for 7 French JR 4.0 (Cordis, Fremont, CA, USA) guide was placed to the RCA. There was a large Posterior Descending artery septal collateral channel to the LAD (Fig. 1c), which looked promising. We first treated the lesions in RCA and PDA with drug-eluting stents under IVUS guidance for securing safety of retrograde approach. Then a Sion wire (Asahi) supported by a 150 cm corsair catheter (Asahi) easily negotiated the channel (Fig. 1d). We began retrograde wiring with a XTA wire (Asahi) but the wire kept slipping into the high septal branch and failed to puncture the distal cap of the CTO (Fig. 1e). Therefore, an Ultimate Bros 3 g wire (Asahi) was used to puncture into the distal cap and wire into the mid portion of the CTO. As there was a sizeable diagonal branch just proximal to the proximal cap of the CTO, we decided not to attempt single retrograde wire crossing for fear of jeopardizing the large diagonal (Fig. 1f). A Gaia second wire (Asahi) was used to wire antegradely into the CTO but this wire went into the antegrade track produced by the previous antegrade attempt and ended up in a small septal branch that emerged about 6 mm into the CTO body (Fig. 2a).

Fig. 2.

(a) Antegrade Gaia 2nd in small septal branch. (b) Failed reverse controlled antegrade and retrograde subintimal tracking (CART). (c) Wire at 4 o’clock — same space as intravascular ultrasound catheter. (d) Wire at 5 o’clock — subintimal position. (e) Stent reverse CART. (f) Retrograde conquest 9 easily wire into stent.

We attempted to redirect the antegrade wire into the main LAD CTO, but it was not possible. Therefore we began contemporary reverse CART in the proximal part of the CTO using first a 2.0-mm balloon, then a 2.5-mm balloon, and even a 3.0-mm balloon. Despite using several retrograde wires including XTA, Gaia second, Gaia third, Sion Black, Conquest Pro 9 (all Asahi); we were unable to succeed in reverse CART (Fig. 2b). An IVUS examination showed that the retrograde and antegrade wires were connected in the subintimal space (Fig. 2c) but proximal to this connection point, the retrograde wire continued in the subintimal position while the antegrade wire was in the true lumen (Fig. 2d). We attempted IVUS-guided wiring but we were unable to wire the retrograde wire back into the true lumen. We did consider the use of a bigger balloon to perform reverse CART or transit balloon technique, but we were concerned that the balloon may slip forward into the small septal branch and cause a perforation. A stent, however, would less likely slip forward and would protect the proximal diagonal. We therefore decided to proceed to stent reverse CART. Under IVUS imaging to guide the distal stent-landing site, we implanted a 3.5 × 15 mm Osiro drug-eluting stent (Biotronik, Berlin, Germany) into the CTO lesion (Fig. 2e), and did IVUS-guided post dilatation with a 3.75 mm Pantera Leo non-compliant balloon (Biotronik) at 16 atmospheres. After this, we could easily manipulate the retrograde conquest pro 9 wire into the stent (Fig. 2f) and into the aorta. We did an IVUS check of the retrograde wire position and found that the wire was inside the stent (Fig. 3a), but we could not pass the IVUS all the way through the distal end of the stent as the antegrade wire was inside a small septal branch that could not accommodate the IVUS catheter. Retrospectively, when we reviewed this IVUS run we could see that the retrograde wire suddenly disappeared from inside the stent when the IVUS was pushed to the most distal part of the stent (Fig. 3b), but we did not notice this during the procedure. We easily manipulated the retrograde wire into the antegrade guiding catheter and began rotating the retrograde corsair through the CTO into the antegrade guiding catheter using a 3.0-mm balloon to trap the retrograde wire inside the antegrade-guiding catheter. However, after the retrograde corsair passed the CTO and exited the left main ostium, it could not enter the antegrade guiding catheter (Fig. 3c) and at this point the patient developed hypotension with a systolic blood pressure dropping down to 80 mmHg and bradycardia down to 40 bpm. Intravenous fluid resuscitation and inotropic support were started while we did an antegrade IVUS to explore what had happened. We noticed that the LAD was free of stent (Fig. 3d) and instead there was an expanded stent just outside the left main in the aorta (Fig. 3e). The IVUS also showed that the retrograde wire was inside the proximal part of the stent but passed through the distal stent struts to outside the stent (Fig. 3f). On cine we could appreciate that the stent was stuck at the ostium of the antegrade guiding.

Fig. 3.

(a) Antegrade wire at 8 o’clock inside the stent. (b) Distal stent retrograde wire drop out. (c) Corsair cannot enter guiding. (d) No stent in Left anterior descending artery. (e) Stent in aorta outside left main. (f) Wire crossed from outside to inside stent at 9 o’clock.

Despite fluids and increasing doses of dopamine, the patient continued to be hypotensive. We postulate that this was due to a combination of ripping the stent off the LAD as well as the tension in the retrograde system. Subsequently, we conducted simultaneous echocardiography examination during retrograde microcatheter pushing and this showed that the loss of longitudinal contraction was due to the pushing out of the apex by the force exerted onto the retrograde microcatheter. Therefore, only releasing the retrograde system can restore the blood pressure. However, despite trying to manipulate the retrograde system to release tension, hypotension persisted. We considered snaring the dislodged stent but after balancing the risks of proceeding with snaring during hypotension and allowing the dislodged stent to embolize, we decided to release the stent and retrieve the retrograde system. Once the retrograde system was retrieved the patient’s blood pressure recovered and he remained stable on inotropic support. Final angiogram of RCA showed no damage to the septal channel.

Subsequent computed tomography scan showed that the stent was dislodged to the carotid artery but was in a stable position and the neurosurgical team considered the risks of snaring it outweighed the risks posed by this dislodged stent. Therefore it was treated conservatively. The patient recovered uneventfully and was discharged.

Discussion

The problem of reverse CART is particularly challenging to retrograde CTO operators. By the time we are performing reverse CART we have usually spent considerable time and effort in antegrade preparation, retrograde channel crossing, and CTO body wiring. Contrast and radiation limits are nearly breached and operator fatigue and patient tolerance reaching their limits. Under these circumstances, it is easy to be tempted to use the “most powerful” reverse CART method, the stent reverse CART.

The solutions that have been proposed to solve the reverse CART problem all involve increasing the antegrade target size, by IVUS-guided large balloon, by guideliner reverse CART, or ultimately by stent reverse CART [1]. On the retrograde side, the solutions have focused on increasing the penetration power of the retrograde wire or placing the wire in the subintimal space by knuckle wiring [1]. However, in the contemporary reverse CART era, we should refocus our solutions toward improving retrograde wire control [4].

We report a case where stent reverse CART was performed but unfortunately the retrograde wire entered the stent lumen through the struts in the side of the stent near the distal end. This led to the stent being dislodged by the retrograde corsair and ultimately embolized to the carotid artery. There are several important lessons to learn from this case.

First, we made the mistake of continuing to use the conquest wire, which is stiff and runs the risk of puncturing through the side struts; we should have used a floppy wire instead. Secondly, we did not take careful cine to look at how the retrograde wire crossed the stent, however, in our defense, today’s thin strut stents can sometimes be difficult to see clearly on cine. Finally, we did not check the retrograde wire position in the very distal end of the stent, which we should have done.

Stent reverse CART is by nature an irreversible procedure, once the stent is implanted, it cannot be removed (ironically it was removed in our case). Therefore, if after the stenting we cannot complete the reverse CART, this will lead to stent thrombosis and infarction due to proximal thrombus propagation. It is important to only use stent reverse CART when IVUS has clearly demonstrated a connection between the antegrade and retrograde wires. If there is no connection, the retrograde wire may fail to enter the distal part of the stent and instead enter via the side of the stent as in our case. Worse still, the retrograde wire can theoretically push the plaque and deform the deployed stent leading to a crushed distal end of the stent. Therefore we believe that IVUS documentation of connection between antegrade and retrograde wires is a prerequisite for stent reverse CART. Also, the use of IVUS to check the retrograde wire position throughout the entire length of the stent is also essential for safe stent reverse CART. The use of a looped retrograde wire to pass the stent is also helpful.

Stent reverse CART is often thought of as the ultimate weapon in reverse CART, but our case clearly shows that serious complications can result from stent reverse CART. There are other options to stent reverse CART, such as guideliner reverse CART as suggested by Joyal et al. [1] and if the guideliner does not provide a big enough antegrade target space, transit balloon technique [3] can fulfill all the benefits of stent reverse CART without the risks. With improving retrograde wires that can be controlled and directed when supported by retrograde microcatheter, stent reverse CART is rarely necessary, if at all. Therefore it is our conclusion that stent reverse CART is not a necessary tool but rather an unnecessary evil and should be filed into the history books of retrograde CTO PCI.

We reported a case of retrograde CTO PCI to LAD using stent reverse CART that was complicated by stent dislodgement. We discussed the importance of IVUS in both confirming a connection between the retrograde and antegrade wires as well as confirming true lumen position of the retrograde wire inside the stent to ensure safety of stent reverse CART. However, in this contemporary reverse CART era where we have directable retrograde wires, and we have the options of guideliner reverse CART and transit balloon technique, stent reverse CART should be the very last resort. Not to toot our own horns, but we do encourage our readers to adopt transit balloon technique in place of stent reverse CART. Stent reverse CART may be considered a rarely necessary evil and not a routine tool.

Conflicts of interest

There are no conflicts of interests in relation to this case report on behalf of all authors