Cutting Balloon Entrapment During Treatment of In-stent Restenosis: An Unusual Complication and Its Management

The Barath Cutting Balloon (CB) (Boston Scientific, Natick, Massachusetts) was designed to score atherosclerotic plaque during balloon angioplasty using 3 or 4 longitudinal atherotomes.¹ This microsurgical dilatation technique allows coronary dilatation with lower inflation pressures than conventional balloon angioplasty, potentially reducing the degree of balloon-induced arterial barotrauma, as well as dilatation of fibrocalcific lesions resistant to conventional balloon angioplasty. A third advantage of the CB is that the longitudinal blades increase axial friction during inflation, reducing the degree of balloon slippage (or “watermelon seeding”) during dilatation of fibrous lesions. Despite its potential to improve late outcomes, a large randomized clinical trial found no difference in late restenosis in patients treated with the CB or conventional balloon angioplasty.² Nevertheless, the CB has been approved by the U.S. Food and Drug Administration for the treatment of “resistant” coronary lesions. Due to its ability to incise fibrocalcific plaque, the CB has been used in coronary lesions resistant to conventional balloon angioplasty,³ small vessels, ostial locations, bifurcations, and for the treatment of patients with in-stent restenosis (ISR) alone⁴ or prior to radiation brachytherapy.^5–7 However, large, randomized clinical trials comparing the CB to conventional devices are lacking. Complications associated with CB angioplasty are infrequent and include coronary dissection,⁸ perforation with cutting balloon oversizing,⁹ and, rarely, entrapment of the CB within a coronary stent during treatment of ISR.^10–13 We present an additional three cases of CB entrapment during treatment of ISR. Causative mechanisms and potential management strategies are reviewed. Methods We retrospectively reviewed all percutaneous coronary interventions (PCIs) performed at out institution between January 1, 2002 and January 1, 2003. Using an electronic medical record, all cases in which the CB was used during this period were identified and were examined for the occurrence of CB entrapment during the procedure. CB entrapment was defined as the inability to immediately withdraw the CB catheter from the dilated lesion after balloon deflation. Procedural angiograms and hospital records were then reviewed for all cases of CB entrapment. Results A total of 2,184 PCIs were performed at the Brigham and Women’s Hospital during the study period. The CB was used in 279 (12.8%) of PCIs. ISR was treated with the CB in 248 cases; radiation brachytherapy was used with CB angioplasty in 157 of these ISR cases. Three cases (1.1%) of CB entrapment were identified during the study period, all occurring during the treatment of in-stent restenosis. Case 1. A 58-year-old diabetic woman with unstable angina 4 months following placement of a 3.0 x 13 mm PENTA^® coronary stent (Guidant Corporation,Santa Clara, California) in her distal right coronary artery (RCA), was found to have a focal, 90% restenotic lesion within the stent. PCI in anticipation of radiation brachytherapy was performed using a 7 Fr JR4 guide and a 0.014 inch BMW wire (Guidant Corp.) that was advanced across the lesion and positioned in the posterior descending artery without difficulty. Predilatation using a 3.0 x 20 mm Maverick™ balloon (Boston Scientific Corporation, Maple Grove, Minnesota) was attempted, but a persistent balloon waist was noted at 10 atmospheres. A 3.25 x 10 mm CB was then advanced within the stent without resistance, but the CB failed to inflate at 10 atmospheres. Withdrawal of the CB met with resistance, thus a 2.0 x 20 mm ACE™ balloon (Boston Scientific Corp.) was positioned alongside the CB and inflated (“buddy balloon” technique), but failed to dislodge the CB. Further attempts at forceful traction of the CB were unsuccessful and coronary bypass surgery (CABG) was performed to remove the CB en-bloc. Examination of the en-bloc specimen showed that the CB had passed behind a stent strut and a blade had become entrapped at the time of CB withdrawal. Case 2. An 81-year-old woman presented with unstable angina four months following PCI with stent placement in the ostium of the saphenous vein graft (SVG) to left anterior descending artery (LAD). Cardiac catheterization showed 95% focal in-stent restenosis of this stent. There was difficulty with guiding catheter engagement in the ostium of the SVG due to stent protrusion into the aorta. A 6 Fr AR-2 guiding catheter was used to advance a PT Graphix™ wire (Boston Scientific Corp.) through the stent and into the distal SVG. An initial attempt to cross the ostial stenosis using a 4.0 x 15 mm CB failed, and a 2.5 x 15 mm Maverick balloon was inflated to 15 atmospheres for predilation. The 4.0 x 15 mm CB was then reintroduced across the lesion and inflated to 10 atmospheres. After repositioning of the CB proximally, a second inflation of 10 atmospheres resulted in CB rupture. The CB then met resistance on withdrawal and could not be extracted, presumably due to the passage of the CB through a stent strut in the aortic ostium. The CB was ultimately extracted with forceful back pressure, leaving a deformed ostial stent. The stent was then further dilated through the committed strut using a 4 mm noncompliant balloon, leaving a 50% residual stenosis with TIMI 3 flow. The patient was discharged home the following day in stable condition. Case 3. A 56-year-old man with a history of remote CABG and multiple prior PCIs to the native left main, LAD, and left circumflex (LCx), represented with angina 3 months following stent placement to the left main, ostium of the LAD, and ostium of the left circumflex. Cardiac catheterization revealed an 80% ISR of the ostial LAD and LCx stents (Figure 1A). Using an 8 Fr XB 3.5 guide, 2 BMW wires were placed into the LAD and LCx. A 2.75 x 10 mm CB initially failed to cross into the LCx, and a 1.5 mm Maverick was passed into both the LAD and LCx. Stabilizer^® XS steerable guidewires (Cordis Corporation/J&J Company, Warren, New Jersey) were then exchanged in both vessels. Subsequent 1.5 x 15 mm and 2.5 x 15 mm balloon inflations were performed in “kissing” fashion on the LAD and LCx bifurcation. Due to considerable recoil in the LCx ostium, a 2.75 x 10 mm CB was then inflated in the LCx ostium at 10 atmospheres 3 times. Attempts to remove the CB failed due to entrapment of the proximal edge of the CB within the stent (Figure 1B). Three maneuvers were then employed to remove the entrapped CB. A 2.5 mm ACE balloon, positioned adjacent to the entrapped CB, was inflated to 10 atmospheres, but the CB could still not be withdrawn (Figure 1C). The ACE balloon was then inflated distally and the guide catheter was advanced over the CB in an attempt to “sheath” the CB into the guide, which was also unsuccessful. The hub (proximal end) of the CB was then cut off and a 7 mm Amplatz Goose Neck^® Microsnare (Microvena, ev3, Inc., Plymouth, Minnesota) was advanced over the CB shaft to the guide tip. The CB was snared and removed through the guide using exceptional force. Final angiography revealed poor flow in both the LAD and LCx, presumably due to stent deformation. After rewiring both the LAD and LCx and performing 2.5 mm kissing balloon inflations, a 2.5 x 13 mm stent was placed in the LAD, and TIMI 3 flow was restored to both vessels (Figure 1D). The patient was discharged in stable condition the following day. Discussion Entrapment after CB use for the treatment of ISR has been described in three case reports.^10,12,13 An additional microtome fracture has also been seen following dilatation of a complex fibrous lesion.¹¹ In all the three cases of CB entrapment in our series, there was likely an inadvertent passage of the wire through an incompletely apposed stent strut that led to the CB entrapment. Our cases demonstrate common scenarios in which CB entrapment may occur. In the event that the stent is incompletely apposed against the vessel wall, the coronary guidewire can inadvertently pass behind the stent strut. Our first case demonstrated an unusual finding of a waist during balloon dilatation of ISR that prompted the use of a CB. In retrospect, the resistant lesion likely represented the passage of the balloon between the stent struts. High-pressure balloon dilatation during stent deployment, and potentially the use of intravascular ultrasound in patients with ISR, may lessen the occurrence of this complication. Our second case demonstrated the passage of a coronary guidewire through the exposed stent struts of an aorto-ostial stent. The occurrence of this event may be lessened if the guidewire is prolapsed when it enters the stent. Our third case demonstrated the passage of a coronary guidewire through the exposed stent struts of an aorto-ostial stent. The occurrence of this event may be lessened if the guidewire is prolapsed when it enters the stent. In aggregate, it is clear from these cases that extra caution should be used when advancing the coronary guidewire through potentially underdeployed or exposed stents. If there is question about the location of the wire, CB angioplasty should be avoided. Strategies for removing an entrapped cutting balloon. A number of strategies can be used to remove an entrapped CB, and some of these techniques were used for the management of patients included in this report. Depending on the size of the guiding catheter selected for the initial CB use, an additional guiding catheter via use of the contralateral groin or upper extremity access may be required. Upon CB deflation, the balloon rewraps, covering the CB blades into distinct folds. Prior to implementing the actions listed below, the CB should be inflated and deflated in an effort to encase the proximal portion of the microtome within the balloon. • Push/pull. An avulsed longitudinal atherotome may be trapped between the stent strut and the vessel wall. The entrapped CB should first be advanced forward and rotated either clockwise or counterclockwise in order to unhook the protruding microtome. • Buddy balloon. If the atherotome has become deformed in its mid-portion that has snagged a stent strut, a second balloon can be introduced alongside the entrapped CB and inflated in order to change the confirmation of the CB and release a stent strut. Although the “buddy balloon” technique may be useful in changing the configuration of the entrapped CB, the risk of balloon rupture from a protruding microtome is possible, but was not experienced in our series. • Guiding catheter “sheath.” With the extreme longitudinal arterial force sometimes required to remove an entrapped CB, the proximal vessel can sustain tractional injury, resulting in proximal coronary dissection. With some 6 Fr guiding catheters, the guiding catheter can be deep-seated within the coronary artery, and the retraction force can be applied at the orifice of the guiding catheter. If the CB has been dilated through a stent strut, this maneuver is unlikely to be successful, but will lessen the degree of traction injury to the vessel. • Snare. If a larger (>= 8 Fr) guiding catheter has been used (or a smaller guiding catheter can be exchanged for a larger one), the hub of the CB can be cut and a Microvena Snare can be placed over the shaft of the CB and its wire. The snare can then be advanced through the guiding catheter to the CB allowing for greater traction force to be directly applied to the entrapped device. • CABG. If the entrapped CB cannot be retracted despite these maneuvers, or if anterograde flow cannot be sustained, surgical consultation for CABG and removal of the entrapped CB should be undertaken. Although this therapy is a last resort, it is required in some cases with refractory CB entrapment. The primary modality for CB use in our laboratory is for the treatment of ISR prior to radiation brachytherapy.^5–7 With the advent of sirolimus- and paclitaxel-eluting stents that have resulted in clinical restenosis rates 14,15 it is likely that the relative use of the CB will shift toward resistant lesions rather than for the treatment of in-stent restenosis, thus minimizing the potential for CB entrapment. Nevertheless, drug-eluting stent restenosis has been reported, and interventionalists may still utilize CB alone, or in combination with either brachytherapy or additional drug-eluting stents. CB is currently being used in patients with undilatable lesions and particularly in those with ISR after bare metal stent placement, where conventional balloon slippage results in extended injury prior to radiation brachytherapy.⁵ Limitations of the CB include excessive cost and poor crossing profile, which make it cumbersome to use at times compared with standard balloons. It is important to recognize the limited efficacy data with the CB and balance this with the potential complications with this device. Cutting balloon entrapment was infrequent in our series, but was related to passage of the coronary guidewire through an exposed or underdeployed stent strut. Although the CB can generally be removed with a number of maneuvers, on occasion, CABG may be required. CB use should be avoided if there is concern that the guidewire has passed between stent struts during the treatment of ISR.

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