The Cutting Balloon® (CB) (Interventional Technologies, Letterkerry, Ireland) employs three to four longitudinally mounted microblades that produce clean incisions into plaque or neointima, enhancing lesion dilatation.1 Its use has been advocated specifically for heavily calcified lesions, aorto-ostial disease, and in-stent restenosis (ISR).2–4 However, the microblades also render the current version of the balloon bulky and stiff. Several recent reports have described CB entrapment following dilatation for ISR, leading to inadvertent extraction of the previously deployed stent.5–8 We describe for the first time a case in which the CB became entrapped during treatment of ISR and could not be removed, with subsequent complete detachment of the CB from the balloon catheter. Case Report. A 72-year old man with extensive comorbidities including severe aortic stenosis, dialysis-dependent chronic renal failure, cerebrovascular and peripheral vascular disease, had undergone two previous percutaneous coronary intervention (PCI) procedures to the right coronary artery (RCA) for de novo disease. A total of five overlapping stents were deployed from the proximal to the distal vessel. After initial symptom relief, he developed recurrent chest pain eight months after the most recent procedure, culminating in admission to a district hospital due to unstable angina. Coronary angiography demonstrated diffuse neointimal hyperplasia, with a focal 90% ISR in the distal vessel, and a focal 70% restenotic lesion in mid-vessel (Figure 1). He was referred for repeat PCI. Procedure. Eptifibatide and intra-arterial heparin (60 units/kg) were administered at the onset of the procedure. The RCA was engaged with a 6 Fr JR4 guiding catheter, and a Balance Middleweight™ guidewire (Guidant Corp., Santa Clara, California) was advanced without resistance to the distal vessel. A 3.0 x 10 mm CB could not be passed across the mid-RCA lesion. A 2.5 x 15 mm Stormer® Balloon (Medtronic, Inc., Minneapolis, Minnesota) successfully crossed both lesions, although considerable resistance was encountered, and deep seating of the JR4 guiding catheter was required to provide sufficient support. The balloon was inflated to 16 atmospheres (atm) in the mid and distal lesions, with no evident waist. It was then possible to advance the 3.0 x 10 mm CB across both lesions, though once again, resistance was encountered and deep seating of the guiding catheter was necessary. The CB was inflated to 8 atm in both lesions, with no waist, and was withdrawn without resistance. Repeat angiography revealed substantial recoil, with significant residual stenosis at the distal lesion and extending back to the mid-vessel lesion. A 3.25 x 10 mm CB was therefore passed to the distal RCA, again with some difficulty. Three sequential overlapping distal-to-proximal inflations of the CB were performed, each to 10 atm. Once again, no waist was observed. Following the last inflation, an attempt was made to withdraw the CB. However, after moving a short distance, the balloon became immobile and could not be pulled back further. Coronary angiography revealed localized dissection and a reduction in antegrade flow to TIMI grade 2 (Figure 2). The patient complained of typical anginal chest pain, but was hemodynamically stable. The CB was re-inflated, initially to 2 atm, then subsequently to 8 atm, and was then deflated to negative pressure in an attempt to improve rewrapping and reduce profile. However, further attempts to remove the CB were unsuccessful and resulted in stretching of the balloon catheter (Figure 3). Efforts to withdraw the CB, guidewire and guiding catheter together were no more successful. We endeavored to deeply engage the JR4 catheter over the CB and then withdraw the CB. However, the guiding catheter could only be advanced part way over the CB, and no further movement of the balloon was achieved. A surgical opinion was sought; however, surgery was not deemed feasible due to comorbidities as well as active anticoagulant therapy. Eventually, further attempts to withdraw the CB resulted in separation of the balloon from the balloon catheter. The entire balloon catheter, with the proximal third of the balloon, but missing the distal two-thirds and all of the microblades, was withdrawn from the patient. Angiography demonstrated the distal marker of the CB still present within the stent (Figure 4). There was persistent dissection and further reduction in flow. After unsuccessful attempts with a second softer guidewire, an extra-support hydrophilic Shinobi coronary guidewire (Cordis Corp., Miami, Florida) coronary guidewire was selected and, with considerable difficulty, manipulated beyond the CB remnant into the distal RCA. A 2.0 x 15 mm Maverick™ balloon (Boston Scientific, Natick, Massachusetts) was inflated adjacent to the disconnected CB, but burst immediately on inflation. A new 2.5 x 15 mm Stormer balloon also ruptured on attempted inflation. A 2.75 x 8 mm Quantum balloon (Boston Scientific) was then chosen, with the rationale that the noncompliant balloon material may be more resistant to bursting on the blades of the fractured CB, and was successfully inflated to 12 atm. Further inflations of the Quantum balloon were performed throughout the stented segment to a pressure of 12 atm. Two 2.75 x 18 mm S660 stents (Medtronic) were deployed, each to 18 atm, to cover the area of dissection and the CB remnant. A gap identified between the stents was covered with a 3.0 x 9 mm S7 stent (Medtronic), deployed at 18 atm. The final angiographic result was excellent, with TIMI grade 3 flow and no residual stenosis (Figure 5). At the end of the procedure the patient was pain-free; he was transferred back to the district hospital the following day in stable condition. He was advised to remain on clopidogrel for 12 months postprocedure. Discussion. The Cutting Balloon has been widely used as a standalone therapy for in-stent restenosis. Although recent randomized trial data showed no improvement in restenosis recurrence versus conventional balloon angioplasty, fewer balloons were needed and, importantly, balloon slippage was less frequent, limiting the extent of trauma.9 In the future, the principal role of the CB is likely to be for dilatation of the restenotic lesion prior to definitive treatment with brachytherapy or drug-eluting stent (DES) deployment; limiting injury outside the treated segment is crucial with both of these therapies.10–12 The principle limitations of the current generation CB are the increased profile and reduced trackability conferred by the stiff microblades. Although the CB is engineered to rewrap after balloon inflation to protect the edge of the blades, the deflated profile is larger still, and may lead to resistance during balloon withdrawal. Four previous reports have described entrapment of a CB during treatment of ISR.5–8 In all four cases, the guiding catheter, guidewire and CB were successfully removed as a single unit, but with inadvertent extraction of the previously deployed stent. In one case, entrapment of the CB was related to unsuspected passage of the coronary guidewire through a stent cell.8 In the others, it was attributed to locking of the microblades in the stent struts, with subsequent avulsion of the struts on attempted withdrawal. In one case, this occurred in association with fracture of the microblade, a recognized complication.6,13 This is the first report of persistent CB entrapment with subsequent detachment of the CB from the balloon catheter. The separation of the balloon from the catheter rather than extraction of the stent may be explicable by the presence of overlapping stents in this case. The mechanism of entrapment remains unclear. It is unlikely that the guidewire had passed through the side of the stent since the initial passage of the guidewire to the distal vessel was smooth, and no difficulty was encountered withdrawing the conventional balloon and the smaller diameter CB that were used first. Furthermore, no focal balloon waist was detected with inflation to suggest dilatation of a stent cell. It seems more likely, therefore, that entrapment was due to locking of a microblade in a stent strut, possibly in association with blade fracture. It has been suggested that inflation of the CB to pressures higher than manufacturer’s recommendations of 6–8 atm may increase the risk of blade fracture, particularly if failure to dilate the restenotic lesion causes uneven balloon expansion resulting in metal fatigue.6 However, the balloon manufacturer’s own product test has established that the pressure level required to cause blade breakdown would be far beyond the 10 atm that we employed.4 We were able to successfully deal with the detached CB by rewiring of the lesion, balloon dilatation and subsequent deployment of further stents to trap the CB remnants in a “stent sandwich”. A number of mechanisms have been employed to remove entrapped stents, including the use of snare devices, myocardial biopsy forceps and low-profile 1.5 mm angioplasty balloon catheters inflated distal to the entrapped device.14–16 However, we were reluctant to try such methods, since further retraction of the CB may have led to extraction of the stent, occlusive dissection or even coronary perforation. This case highlights the care that should be employed when using the CB in the treatment of ISR. Firstly, the indication for CB should be considered carefully, given the lack of clear superiority to conventional balloon angioplasty in the only randomized trial available. If difficulty is encountered advancing the CB, preliminary dilatation with a standard balloon should be employed. The interventionist should be alert to the possibility of wire passage through stent cells. Excessive resistance to advancement of the balloon should be interpreted as an indication of this, and rewiring considered. Where doubt exists, intravascular ultrasound can be used to confirm that the wire is within the stent lumen throughout its course.16 The manufacturer’s guidelines for balloon inflation should be adhered to (1 atm inflation every 5 seconds; maximum 6–8 atm). Some operators also recommend deflation of the balloon at the same gradual rate. Finally, withdrawal of the CB should not be attempted until an adequate time interval has elapsed to allow full rewrapping of the balloon. Gentle advancement of the balloon before withdrawal is also advisable to unlock the microblade from the stent strut in case locking has occurred. The CB will continue to be a useful device in the interventionist’s armamentarium for the treatment of in-stent restenosis. However, this case illustrates the difficulties that can be encountered, and emphasizes the care that should be taken to avoid them.
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