Migration of an Embolized Deployed Stent from the Left Main with Subsequent Crushing: A New Use for the IVUS Catheter?

ABSTRACT: Coronary stent dislodgement and loss carries significant morbidity and risk of infarction and thrombosis if left untreated. There have been multiple previous techniques for stent retrieval or deployment after stent loss including wire braiding, distal small balloon retrieval technique, snare use, forceps in large vessels and the stent crush technique.^1–4 We report an unusual case of a largely deployed stent which was iatrogenically embolized retrogradely to the left main and its migration using an IVUS catheter with successful stent crushing in the proximal circumflex with good angiographic and medium term clinical outcome.

J INVASIVE CARDIOL 2010;22:E19–E22

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Case Report. A 64-year-old male with a positive stress test presented to the catheterization lab with class 3 angina on good medical therapy. Angiography demonstrated a normal left main artery. The left anterior descending artery had mild disease only. A major diagonal had severe 75–80% mid body disease (Figure 1). A large obtuse marginal (OM) had an 85–90% in its proximal segment (Figure 2). The right coronary artery had mild to moderate disease only. After discussion with the patient, intervention was planned on the OM and diagonal vessels. The left main was engaged with a VL 3.5 6 Fr guiding catheter. A Prowater wire™ (Abbott Vascular, Santa Clara, California) was advanced down the OM1. The lesion was then pre dilated with a 2.25 x 12mm balloon at eight atmospheres. Subsequently a 2.75 x 15 mm Vision® (Abbott Vascular) was passed into the OM (Figure 3A). During deployment, unfortunately the stent was pulled back while being deployed inadvertently by the assistant due to an inadvertent tugging backward while holding onto the balloon catheter and wire with the dilatation pressure at 8 atm at this point. On the CINE, the stent was found to have migrated to the left main at this point (Figure 3B). Upon deflation of the balloon, the residual backward force on the balloon and other equipment made the wire and balloon both come out of the left main with subsequent loss of balloon and wire. At this point we had a partially deployed stent in the left main with loss of wire access. The patient remained hemodynamically stable with no chest pain and good TIMI 3 flow in all vessels. We went through our options of snaring this deployed stent vs. crushing it in the left main with a larger drug eluting stent. Ideally, our goal was to not disrupt the left main or stent it if avoidable. First under increased magnification, both the OM and diagonal vessels were rewired around the stent and not through it. Our plan was to deal with the distal lesions in the OM and diagonal first in case these would not be accessible at a later point. The guider was advanced somewhat deeply into the left main to ensure that the free stent would not embolize backwards into the aorta. Next, to prove stent mobility, a balloon was inserted over the circumflex wire which caused the free stent to be displaced to the superior aspect of the left main in the caudal view, this demonstrated complete mobility of this detached stent (Figure 4). Next, we passed a 2.75 x 16 mm Taxus® (Boston Scientific Corp. Natick, Massachusetts) drug-eluting stent into the OM and this was deployed at 12 atm and post-dilated with a 3.25 x 8 mm noncompliant balloon at 18 atm throughout with an excellent result (Figure 5). Next, a 2.5 x 12 mm Taxus DES was deployed in the diagonal at 14 atm with good effect (Figure 6). At this point there was an option of snaring the detached expanded stent vs. trying to migrate it distally where it could be crushed. We first thought to perform intravascular ultrasound (IVUS) to localize the exact anatomy and location of the detached stent. This was performed using the Atlantis Pro 40 MHz IVUS catheter (Boston Scientific). The IVUS demonstrated the stent to be deployed in the left main with a slant toward the circumflex ostium (Figure 7). Our hope was to catch the proximal edge of the deployed stent with the IVUS catheter and gently migrate it down the circumflex if possible. Fortunately, during gentle manipulation during the second IVUS run, we were able to catch the proximal strut of the deployed stent with the mouth of the IVUS catheter and ease it into the proximal circumflex (Figure 8). This then enabled us to deploy a 3.5 x 16 mm Taxus Liberté in the proximal circumflex with its proximal 1–2 mm struts in the distal left main at 18 atm, thereby crushing the previous detached stent against the wall of the circumflex (Figure 9). Next, a 4.0 x 12 mm Quantum™ (Boston Scientific) noncompliant balloon was used to further maximize expansion of the 3.5 mm Taxus stent and ensure complete crushing of the detached Vision® (Abbott Vascular) stent against the proximal circumflex wall. The distal mouth of the detached stent was protruding into the ongoing circumflex/OM2 (Figure 10). This vessel was then wired with a Prowater wire and a Sprinter 1.5 x 10 mm balloon was used to cross the struts and dilate the distal portion of this stent facing the OM2. Subsequent kissing inflations were performed with a 4.0 x 12 mm Quantum in the circumflex and a 2.25 x 12 mm Apex balloon in the OM2 ostium to flare the nose of the stent into the OM2 (Figure 11). This gave a good angiographic result with complete stent crushing, no residual stent in the left main and no side branch loss (Figures 12 A and B). Intravascular ultrasound was repeated at the end to demonstrate complete crushing and no residual stent in left main and this was the case (Figure 13). The patient is doing clinically well and remains asymptomatic at 3 month follow-up. Discussion. Stent dislodgement and loss can be a devastating complication of percutaneous coronary intervention. In this case, a very unusual iatrogenic complication of stent embolization occurred due to unintentional catheter tugging and subsequent withdrawal of a deployed bare metal stent into the left main. Many options need to considered in such a scenario including surgical backup, snare retrieval and stent crushing. Given the very mobile nature of the detached and deployed stent, we chose to migrate this stent distally into the proximal circumflex and then to crush it subsequently. This was done with the aid of the IVUS catheter interestingly, since it managed to “catch” on the proximal struts of the stent and helped to gently migrate it into the circumflex. Our thought was that snaring a deployed stent as opposed to an undeployed stent had a higher potential for left main injury given the usual distortion and “mangling” of stent architecture that occurs with withdrawal with a snare. If the migration technique had not been successful, snare retrieval was our next default option. Deployed stent migration using the tip of an IVUS catheter has not been described to our knowledge in previous reports. If the IVUS catheter had not “caught” on the stent edge, a small inflated balloon down the LAD or nontarget vessel for migration may also have been successful at nudging the stent along its course into the proximal circumflex. The stent migration was performed so as to avoid performing crushing and stenting in the left main at all and to potentially avoid left main stenting in a healthy left main artery. There are multiple caveats and assumptions to this approach. Firstly, detached stents are usually undeployed and become detached due to catching on calcified vessels or when withdrawing back into the guiding catheter most commonly. This was not the case here. This is quite an unusual and unfortunate circumstance of a deployed stent iatrogenically retrogradely embolized to the left main. The usual stent retrieval techniques of distal small balloon and pullback or wire braiding have been described for undeployed stents and not for our scenario. Although distal wire braiding could still have been utilized for this situation, with one wire through the detached stent and another wire outside the stent. Although snaring was contemplated as a second option for this deployed stent, it remains a very useful tool for retrieving most detached devices. Our technique of migrating this deployed stent is not without potential risk including vessel injury, dissection, infarction and thrombosis. Therefore demonstration of free stent mobility is critical and it is also important to ensure that in an emergency such as acute vessel closure, it is always possible to pass a second stent alongside the detached stent for rapid crushing if needed. Both, demonstration of stent mobility and the ability to pass the distal stents around the detached stent were achieved in our case. This technique of stent migration may be a useful tool in rare situations such as in this patient where unfortunate embolization of a deployed stent may occur.

References

1. Brilakis ES, Best PJM, Elesber AA, et al. Incidence, retrieval methods and outcomes of stent loss during percutaneous coronary intervention: A large single centre experience. Catheter Cardiovasc Interv 2005;66: 341–342. 2. Ahmar W, Malaiapan Y, Meredith IT. Transradial retrieval of a dislodged stent from the left main coronary artery. J Invasive Cardiol 2008;20:545–547. 3. Wongpraparut N, Yalamachili V, Leesar MA. Novel implication of combined stent crushing and intravascular ultrasound for dislodged stents. J Invasive Cardiol 2004;16:445–446. 4. Veldhuijzen FL, Bonnier HL, Michels HR, et al. Retrieval of undeployed stents from the right coronary artery: A report of two cases. Cathet Cardiovasc Diagn 1996;39:271–276.

_________________________________________ From St. Boniface General Hospital, University of Manitoba, Winnipeg, Manitoba, Canada. The authors report no conflicts of interest regarding the content herein. Manuscript submitted July 7, 2009, provisional acceptance given August 20, 2009, final version accepted September 14, 2009. Address for correspondence: Dr. Farrukh Hussain, Assistant Professor of Medicine, Interventional Cardiology, St. Boniface General Hospital, Y-3012, St. Boniface General Hospital, Winnipeg, Manitoba, Canada. R2H-2A6. E-mail: fhussain@sbgh.mb.ca