Intracoronary Imaging with Optical Coherence Tomography after Cutting Balloon Angioplasty for In-stent Restenosis

Optical coherence tomography (OCT) represents a promising new technology^1–2 for imaging the vascular microstructure at a level of 10–20 mm,^3–6 which has not yet been achieved with the use of other imaging modalities.^7–9 It may permit the determination of small structural details such as intimal flap width and the presence of fissures, as well as the width of intimal caps^10–12 or malapposition of a stent.¹³Case Report. Cutting Balloon® (Interventional Technologies, San Diego, California)¹⁴ angioplasty was performed for in-stent restenosis of an Easy Wallstent™ (Boston Scientific, Maple Grove, Minnesota) 6.0 mm x 100 mm implanted in the left superficial femoral artery in a 63-year-old Japanese male with a history of hypertension. The Fontaine class was IIa. An angiogram showed diffuse and tandem stenosis (Figure A). Since the Easy Wallstent™ was well-dilated by intravascular ultrasound (IVUS), we selected a 5.5 mm x 10 mm Cutting Balloon. It was inflated multiple times to cover the entire stent at 6–10 atms. The balloon was inflated several times for the same stenosis at increasing inflation pressures. Comparison of the IVUS image with that of OCT (Image Wire™, LightLab Imaging, Inc., Westford, Massachusetts) yielded the following results: at baseline, the stent lumen was filled with a hypoechoic mass. Each stent strut could be detected, although the strut edge was ambiguous by IVUS (Figure B). OCT (Figure C) revealed that the plaque was signal-rich and homogenous. The deep segment was signal-poor, most likely due to attenuation. Each stent strut could be well-delineated and they were detected to be as thin as the expected thickness. This plaque was classified as fibrous according to the classification of Yabushita, et al.¹⁵ After the cutting balloon procedure, OCT detected many fine flaps floating in the lumen (Figure E), while IVUS (Figure D) was unable to detect them separately. The contrast between the vessel surface and blood was excellent in OCT, but poor in IVUS. Discussion. To the best of our knowledge, this is the first report showing the OCT images after cutting balloon angioplasty. Cutting balloon angioplasty is thought to be less invasive than plain-old balloon angioplasty based on its dilatation mechanism,¹⁴ and intimal flaps can be incised without over-dilatation of the vessel and at a lower inflation pressure due to the action of three or four blades on the cutting balloon.¹⁴ After cutting balloon angioplasty, the lumen surface of the stenosed artery has been shown to be smooth, with cut incisions formed by microcatheters. Adamian, et al.¹⁶ reported good late results with a cutting balloon for in-stent restenosis. The angiographic results are often very excellent, with stent-like results showing a very smooth lumen border. However, we sometimes experience restenosis with cutting balloon use, even in cases that produce optimal initial results according to angiograms and IVUS. According to the OCT images, the lumen surface was not smooth, but rather very irregular with fine floating flaps, despite the fact that the IVUS images showed acceptable results in this case. This may partially contribute to the formation of thrombosis or inflammation, causing intimal hyperplasia and, finally, restenosis. This technology may offer a new approach for interventional cardiologists.^17,18shigeito5@hotmail.com

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