Finite Element analysis of Left ventricular wall motion and pressure during diastolic filling have allowed determination of regional variation of stiffness or Young's Modulus of the myocardium. Additionally, it has also been shown that this regional stiffness increases with ischemia. However, the potential of this methodology in delineating """"""""normal"""""""" and """"""""Ischemic"""""""" myocardium based on its regional stiffness has yet to be fully utilized in a clinical setting. The primary reasons for this, we believe, are: (1) No well controlled in vitro model studies have yet been done to establish accuracy and reproducibility of the finite element technique to predict regional stiffness of an irregular nonlinear chamber that simulates the left ventricle. (2) Effect of poor primary data used in the finite element analysis (e.g. poor wall definition of the Echocardiographic images; no wall thickness data in angiographic images) in producing error in the estimate of the regional stiffness has not been studied. Also the potential of minimizing the error by using the state-of-the-art imaging technique such as Cine-CT have not yet been explored. This research project proposes to undertake studies in these two areas. The plan essentially is to (1) construct a three- dimensional silastic chamber of variable regional stiffness simulating left ventricular chamber. (2) To subject this chamber under pulsatile pressure within physiological ranges and obtain wall deformation images by direct high speed VCR image acquisition and Cine-CT. (3) Use a nonlinear finite element analysis to determine regional stiffness distribution of the silastic LV chamber. (4) Determine stiffness of test samples by direct testing in INSTRON. These samples will be obtained from the same silastic LV model described above. (5) Compare the regional stiffness values obtained by studies mentioned above to determine the accuracy of finite element method. (6) In vivo open chested canine studies in Cine-CT to determine alteration in regional myocardium stiffness due to ischemia. (7) Streamline the protocol and software for routine use in clinical laboratories. This research, we believe, will provide a clinical tool to deliniate """"""""normal"""""""" and """"""""Ischemic - yet Viable"""""""" myocardium from analysis of Left ventricular wall motion.
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