Novel Implication of Combined Stent Crushing and Intravascular Ultrasound for Dislodged Stents

An impending consequence of unsuccessful stent deployment is the dislodgement of a stent from its delivery catheter with loss of the stent or embolization. A number of techniques to retrieve stents have been described, including the use of a distally placed angioplasty balloon,1 a second wire,2 forceps,3–5 retrieval snares,6,7 baskets,4 emboli containment devices8 and surgical removal.9–11 These techniques have been described and successfully used in some cases; however, these approaches are difficult, time-consuming and sometimes distressing. Crushing an undeployed stent by an angioplasty balloon and then by another stent is substantially easier than stent retrieval.12 In addition, the potential to cause dissection or precipitate thrombosis is greatly diminished.12 However, crushing an undeployed stent in an atherosclerotic or calcified segment of coronary artery may induce incomplete expansion of the second stent, which may precipitate stent thrombosis or restenosis. The use of intravascular ultrasound (IVUS) in conjunction with stent crushing to assess the second stent expansion has not been previously reported. This report describes a novel technique of combined stent crushing of an undeployed stent and the use of IVUS to achieve optimal stent expansion. Case Report. A 47-year-old man with a history of hypertension and hyperlipidemia was admitted to the hospital with unstable angina. Despite continuation of medical therapy, including the use of intravenous heparin as well as glycoprotein IIb/IIIa receptor antagonist (eptifibatide), the patient’s chest pain persisted and was referred for emergency cardiac catheterization, which demonstrated a 90% stenosis with evidence of possible thrombus in the proximal left anterior descending (LAD) coronary artery and an 80% stenosis in the mid portion of the right coronary artery (RCA); the left circumflex coronary artery had some luminal irregularities, with no significant stenosis. The RCA had an aberrant takeoff and there was moderate tortuosity in its proximal portion (Figure 1A). Left ventricular ejection fraction was 50% with anteroapical hypokinesis. After cardiac catheterization, the patient underwent successful direct stenting of the proximal LAD stenosis, and a 3.5 x 13 mm Penta stent was deployed at 18 atmospheres (atm). The patient’s chest pain resolved after stenting of the LAD, but his creatine kinase (MB) rose to 40. The RCA stenosis was long and critical and there was a concern that after discharge from the hospital the patient might develop the recurrence of angina; therefore, he was brought back to the catheterization laboratory on the third day of admission for percutaneous coronary intervention (PCI) of the RCA. A 6 French (Fr) multipurpose guiding catheter was used to engage the ostium of the RCA. A 0.014´´ Choice PT guidewire was advanced into the RCA and positioned in the distal portion of the artery. A 3.0 x 23 mm Penta stent was advanced over the guidewire to position it across the stenosis. However, after multiple attempts, the stent could not be advanced through the tortuous segment of the proximal RCA and the guiding catheter was disengaged from the ostium of the RCA, which pulled the guidewire and stent delivery catheter out of the RCA. Thereafter, the guiding catheter, stent delivery catheter and guidewire were removed as a whole unit. However, it was noted that the stent had slipped off its delivery catheter and was trapped inside the proximal segment of the RCA (Figure 2A). Because the multipurpose guiding catheter did not provide an adequate opposite aortic wall support, an Amplatz guiding catheter (AL 0.75) was engaged into the ostium of the RCA and a 0.014´´ Sport guidewire was advanced into the RCA. A 3.0 x 15 mm Maxxim balloon was advanced over the wire, inflated distal to the undeployed stent in the proximal RCA, and slowly pulled back to the guiding catheter, which did not trap the undeployed stent. Subsequently, the balloon was readvanced, positioned parallel to the stent and then inflated to a maximum pressure of 15 atm to crush the undeployed stent against the vessel wall. Thereafter, A 3.5 x 25 mm NIR stent was advanced, positioned side by side along the crushed stent in the proximal RCA and then deployed at 15 atm. A 3.5 x 20 mm Quantum Ranger balloon was advanced, positioned inside the stent and inflated at 20 atm. Finally, a 3.0 x 25 mm NIR stent was advanced, positioned across the mid RCA stenosis and deployed at 17 atm. The RCA angiogram revealed straightening of the proximal segment of the RCA with no residual stenosis, and an 80% stenosis in the mid portion was reduced to Discussion. Coronary stenting has become the mainstay of PCI due to its better angiographic success rate and decreased restenosis rate than balloon angioplasty. Cantor et al.13 reported a series of 1,303 PCI procedures and found that failure to deploy stents occurred in 8.3% of cases and was related to a 6-month mortality rate of 39%, probably as a result of remaining residual stenosis or dissection. Others14 reported that failure of stent delivery was associated with significant requirement for urgent bypass surgery (6.9%). Previous studies identified a number of clinical and angiographic factors associated with failed stent deployment, including severe tortuosity,15 using coiled or hand-mounted stents,15 suboptimal guiding catheter position,13 and attempting to pass a stent through a previously deployed stent to a more distal lesion.13 In our case, a number of factors contributed to stent deployment failure, including proximal vessel tortuosity, suboptimal guiding catheter back-up and vessel calcification. Strategies that should have been implemented prior to stenting to prevent the stent dislodgement include an optimal guiding support, use of an extra-support guidewire, predilation with a balloon and the use of a shorter stent. A number of methods have been described to retrieve dislodged stents. Veldhuijzen et al.2 reported retrieval of an undeployed stent by a technique using a second guidewire, which was advanced distal to the undeployed stent. After advancing a second guidewire and twisting both ends of the guidewires by a torquer device, the guiding catheter, guidewires and stent were removed from the coronary artery. Foster-Smith et al.4 reported the successful use of 3 commercially available retrieval devices, including the nitinol gooseneck snare, biliary forceps and the multipurpose basket to remove dislodged stents. Webb et al.8 used an angioplasty guidewire incorporating a distal occlusion balloon (Guardwire) to remove an undeployed stent. Rozenman et al.1 advanced a 3 mm ACE balloon alongside a dislodged stent into the distal part of a vein graft where the stent was dislodged. The balloon was inflated distal to the dislodged stent and the whole system was then withdrawn as a unit. The removal of dislodged stents with all of the techniques described above requires that a guidewire remain in the central lumen of a stent. Feldman12 suggested an alternative approach by crushing the undeployed stent underneath another stent; the undeployed stent is thus excluded from the circulation by deploying the second stent. The time and difficulty involved in simply excluding an undeployed stent from the circulation by placing it under a deployed stent is remarkably easier and avoids the disturbances that often occur when trying to retrieve a lost stent. In addition, since the stent was not riding on the guidewire in this case, the options of advancing a second guidewire or snaring the stent as reported by others2,6,7 were deemed impossible. The use of IVUS in this case assured authors that the stent was well deployed and adequately expanded to prevent complications such as stent thrombosis and restenosis. Furthermore, the use of IVUS enabled the authors to rule out dissection of the vessel wall and to evaluate the status of the crushed stent. The present case demonstrates that the technique of crushing an undeployed stent combined with IVUS use is remarkably easier and faster than a number of tedious stent retrieval techniques. It could be used safely and effectively in preference to a number of challenging stent retrieval techniques. Of note, every attempt should be made to ensure that the guidewire is outside of the stent to be crushed; otherwise, the wire will be entrapped. Before attempting to crush the stent, passing a balloon distal to a stent and withdrawing the partially inflated balloon indicates that the wire has not passed through a stent strut, and the technique can then safely be employed.

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