In vivo estimation of coronary mechanical wall deformation and its relation to plaque formation

When a coronary artery moves, the wall has to change shape. Thus in each cardiac cycle some regions of the wall contract and some dilate. The stress on the coronary wall during ventricular contractions can be calculated by tracking elements in the arterial wall throughout the cycle and calculating their deformation. The method employs a 3D reconstruction process to generate model input for a structural mechanical finite elements package. The reconstruction algorithm is applied to biplane angiogram images taken at different stages of the cardiac cycle and the data fed into a package to generate the corresponding meshed model configurations. The calculation of conformational stress requires two further assumptions: the minimal residual stress state is selected to be the configuration just prior to systole, and secondly, a model for material properties of coronary artery walls has to be assumed. We have developed packages in Mathematica™ 4.1 for construction of meshed arteries, estimating local conformational deformation and associated stress quantities.