Differential remodeling after balloon overstretch injury and either β- or γ-intracoronary radiation of porcine coronary arteries

Abstract Background: Restenosis is a consequence of both neointimal hyperplasia and vessel remodeling. Prior studies have shown that intracoronary radiation (IR) prevents neointima accumulation, but its contribution to vessel remodeling is unknown. The purpose of this study was to evaluate the effect of IR on differential vascular remodeling after balloon angioplasty in porcine coronary arteries. Methods: A total of 20 juvenile swine (30 coronary arteries) were subjected to overstretch balloon injury (BI) followed by IR with either β- or γ-radiation ( 90 Y or 192 Ir). After 2 weeks following treatment, serial tissue sections were perfusion fixed and stained by hematoxylin and eosin (HE control: 3.6±0.7 mm 2 ). In contrast, the DReg was increased following IR, as demonstrated by the FL and the calculated area of the injured segment (control: 2.7±0.5 mm 2 ; β: 5.5±1.1 mm 2 , γ: 5.5±1.1 mm 2 , P Conclusion: We consider that the global arterial remodeling after IR is a heterogeneous process that includes the absence of retraction in an UReg and a positive remodeling in the DReg as shown in the porcine coronary model. These changes in adventitia and neointima appear to contribute to differential vascular remodeling caused by IR in injured vessels.