The cardiac support device, CSD, which is a net covering the patient's heart to prevent cardiac dilation has been focused In this study, an optimum design method for patient specific 'order-made' support net is developed, which fit the patient's heart shape completely The patient's 3D model heart is constructed using MR imaging In order to evaluate our method, the heart model is represented as a hexahedrons mesh and numerically analyzed its behavior using the finite element method The deformation of the heart model during one cycle beat is calculated and the leftward shift of P-V loop when the net is used is shown which means the prevention of heart dilation