The goal of this study is to optimize the transfer of acoustic energy deep in the body. In order to find suitable acoustic paths for the energy transfer to be efficient, we propose a model of ultrasound propagation that takes into account a realistic geometry of the tissue layers inside the human body. The data from the Visible Human Project is used to identify the tissues between the transducer array and the target point located on the epicard of the heart. The model is validated by comparison with measurements of the pressure field radiated by a focused 64-element array in water. Then, model results are presented in a realistic configuration, choosing a suitable input acoustic power so that adverse bio-effects are minimized. The model predicts the amount of acoustic energy that can be obtained at the target point, and is therefore useful to select the best acoustic path among several possibilities.