Echolucent Restenotic Tissue After Brachytherapy
In January 2000, a 56-year-old woman was treated with rotational atherectomy and adjunct balloon angioplasty because of multiple episodes of in-stent restenosis of the right coronary artery. She was then enrolled in the open-label brachytherapy protocol WRIST PLUS (Washington Radiation for In-Stent Restenosis Trial with 6 months of Plavix), which consisted of intracoronary γ-radiation followed by 75 mg/d clopidogrel for a period of 6 months. Six months later, angiography and intravascular ultrasound (IVUS) were performed (Figure⇓). She had recurrent in-stent restenosis extending proximal (between the dark arrows on the angiogram) and distal to the stented segment. The IVUS imaging of this in-stent restenosis area proximal to the stent showed echolucent (dark) tissue (double white arrows). The recurrent lesion was treated with restenting.
Previous studies have shown that in-stent neointimal hyperplasia consists predominantly of spindle-shaped mesenchymal cells (α-actin–positive smooth muscle cells) with very little collagen and elastin.1 2 3 4 The corresponding IVUS image is hypoechoic but not echolucent. Brachytherapy is a promising alternative for treating in-stent restenosis. The echolucent appearance of the restenotic tissue in the current case is an unusual phenomenon in IVUS imaging. This has been termed a “black hole.” We speculate that this black hole of echolucent tissue is caused by the fact that the tissue is acellular and necrotic and lacks connective tissue elements.
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The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
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- Copyright © 2001 by American Heart Association
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