Simulation of the motion of the heart

Abstract

This paper describes a simulation of the motion of the heart during the heart cycle. It considers the heart as a body with two cavities representing the combined atria and ventricles, respectively. It is coupled to the frame (chest) by viscoelastic eZe ments. In the first part of the paper this heart- frame system is described by equations for the relative translation and rotation of its parts. The factors affecting the motion are blood flows into and out of the heart, the changing shape and distribution of the mass of the heart, and the mechanical coupling. Two models were formulated. The first one included some nonlinear terms, and the second was linearized. Both were tested, and results obtained from the linearized model show that it describes the system adequately. This model can be incorporated into existing analog models of the circulation. It considers only one-dimensional translation and neglects the nonlinear effects of flows. The relationship between the position of the centre of gravity of the heart and its volume and shape is linearized. Results obtained from this model for the contribution of the heart to the human ballistocardiogram (the main purpose of the model) are shown and discussed. The main problem at this stage seems to be the lack of data describ ing the mechanical properties of the system.