Tangible modelling of ventricular aneurysm

Myocardial infarction (MI) may cause left ventricular aneurysms (LVAs) as the long-term and obsolete complications. Following MI, the scar will replace the necrotic lesion within a few weeks. As a result, a portion of the left ventricular free wall protrudes, which leads to appearance of LVAs. The three dimensional echocardiography, the computed tomography and the magnetic resonance imaging (MRI) are the most effective tools to diagnose the left ventricular volumetric function and its wall motion. And the primary choice to treat LVAs is surgical therapy, which is called the left ventricular reconstructive surgery (LVRS). The LVRS such as Dor procedure is performed to resume the left ventricular shape and its original myocardial fibre orientation as much as possible. Furthermore, we also have to consider the location of the couple of papillary muscle in order to maintain the mitral valvular functions. When the ventricle dilates due to the obsolete MI, the papillary muscles might be displaced away from the mitral valvular annulus, leading to decreased coaptaion of the mitral leaflets and mitral regurgitation. As the clinical status, the surgeons establish the surgical planning of LVRS according to their design, evidence and experience base on the diagnostic imaging, which is difficult to estimate the postoperative cardiac function and structure quantitatively. The purpose of this study was to support surgeons to examine more quantitative surgical strategies by dint of engineering approach as fabrication of diseased ventricular tangible elastic model and numerical analyses in each patient prior to the treatment. Then we developed a prototyping method of fabrication for elastic ventricular models by the normal sequence of MRI data, which could show the identical and quantitative representation of diagnostic imaging. It is anticipated that these methods could realise the quantitative images and expressions as well as the intercommunity to the strategy of surgical therapy to reduce the patients' risk. As the results: a) An engineering method for the three-dimension reconstruction of diseased ventricular configuration from MRI in cardiac end-systole and end-diastole was established. By using of this method, the evaluation of ventricular motive displacement could be realized and farther researches could be performed base on the reconstructed data. b) A distinctive short-term process for fabricating tangible elastic diseased ventricular model was established. The models could give the surgeons a tangible image of the diseased ventricular shape. On the other hand, preoperative investigations of ventricular blood volume and morphological characteristic could be accomplished. c) The presentation of ventricular wall stress distribution around the diseased lesion was simulated by the finite element method (FEM). According to the result of numerical analyses, it was indicated that the stress distribution was greatly related with the ventricular shape. Moreover, the boundary between the diseased lesion and normal portion, which is important for the decision of surgical position, was shown distinctly.