Towards myocardial contraction force image reconstruction for heart disease assessment and intervention planning

It is clinically vital to devise a technique to evaluate regional functionality of the myocardium in order to determine the extent and intensity of local damage to the cardiac tissue caused by ischemic injuries. Such a technique can potentially enable cardiologists to discriminate between reversible and irreversible ischemic injuries and to devise appropriate revascularization therapy in case of reversible lesions. The technique is founded on the premise that sufficient contraction force generated by the cardiac tissue can be regarded as a direct and reliable criterion for regional analysis of tissue healthy functionality. To this end, a number of imaging techniques have been developed and, to our knowledge, none of them assess regional cardiac functionality based on a straightforward mechanical measure such as local cardiac contraction forces. . As such, a novel imaging technique is being developed on the basis of quantification and visualisation of local myocardial contraction forces. In this technique, cardiac contraction force distribution is attained through solving an inverse problem within an optimization framework which uses iterative forward mechanical modelling of the myocardium. Hence, a forward mechanical model of the myocardium which is computationally efficient, robust, and adaptable to diverse pathophysiological conditions is necessary for this development. As such, this paper is geared towards developing a novel mechanical model of the healthy and pathological myocardium which considers all aspects of the myocardial mechanics including hyperelasticity, anisotropy, and active contraction force. In this investigation, two major parts, including background tissue and reinforcement bars (fibers) have been considered for modelling the myocardium. The model was implemented using finite element (FE) approach and demonstrated very good performance in simulating normal and infarcted left ventricle (LV) contractile function.