A Methodology for Quantifying Deformations in Stented Coronary Arteries Based on Three-Dimensional Angiography

Coronary arteries possess a curvilinear shape as observed in all vascular trees and undergo a cyclical deformation due to their attachment to the myocardium. Implanted stents result in a permanent alternation of the curvilinearity of the artery. It has been hypothesized that the frequently observed straightening effect of stents implies an uneven distribution of forces within the arterial wall, potentially augmenting the injury reaction of the vessel wall and thereby increasing the rate of restenosis. When a target vessel is very tortuous or its shape changes dramatically during the cardiac cycle, the implanted stent may fracture due to complex bending forces induced from the artery movement. Stent fractures have been reported in coronary and pulmonary artery stenting, aortic coarctation, and peripheral vascular stenting such as femoropopliteal artery, renal artery, common iliac artery, and subclavian artery or even nonvascular stenting such as gastrointestinal tract. It is believed that stent fracture is likely to be affected by a large flexion induced from body movement (e.g., such as knee bending or leg crossing) or cyclic flexion subject to cardiac motion. Additionally, stent fracture might be also associated with the high incidence of target lesion revascularization. It is the intent of this paper to propose a methodology to quantify artery deformation subject to cardiac motion and shape alternation caused by device implantation that are applicable today and also generic to other vascular trees created from the same or different imaging modalities. In experiments, two typical human coronary arterial trees are presented, and the validation study by use of intra-coronary marker wires is reported.