The bright and the dark sides of brachytherapy: mechanisms of stenosis reduction and findings of intracoronary β-radiation therapy revealed by IVUS-3D and QCA

Sincethe first percutaneous coronary intervention, 24 years ago, the field of interventional cardiology has continued to grow rapidly. Although PTCA has demonstrated superiority to medical therapy in alleviating angina, restenosis and acute closure of the treated vessel remained major limitations. Stent has improved both problems by preventing residual dissection, elastic recoil and negative remodeling. However, the occurrence of restenosis after stenting remains unresolved. Furthermore, in-stent restenosis has become a new enemy in the field of interventional cardiology, since the conventional treatment of in-stent restenosis is rather disappointing with high restenosis rates (around 30 - 70%). Therefore, the holy grail to overcome this immense enemy went unabated. Intracoronary brachytherapy is a powerful therapy to prevent restenosis after percutaneous transluminal coronary intervention. The purpose of this thesis is to explore the mechanism of action of intracoronary radiation and the problems related to this procedure. For this purpose, three-dimensional intravascular ultrasound (IVUS) and quantitative coronary angiography (QCA) were applied as investigational tools. This thesis consists of 2 parts; the first part deals with the positive aspect of intracoronary brachytherapy which explains its increasing application (Chapter 2) and its mechanistic interpretation (Chapters 3-7). The second part reports on the dark sides of intracoronary brachytherapy (Chapters 8-12).