In vitro experimental system for ultrasonic estimation of myocardial elasticity

An experimental system for investigating cardiac eigenvibration myocardial elastometry (CEME) in vitro was developed. Since CEME is based on a critical assumption that the left ventricle in diastole is approximated as a spherical shell made of a homogeneous material, it does not take into account two key factors that affect eigenvibrations: heart-shape complexity and myocardial inhomogeneity. In the present study, three models of silicon shells (soft, stiff, and ischemic) were used to verify the above-mentioned assumption. To investigate shape complexity, the heart shape was examined by using a commercial heart model. To investigate myocardial imhomogeneity, an ischemic model was created by replacing the soft silicon in the heart apex region by a stiff one. It was found that the eigenfrequency of the soft-shell model is lower than that of the stiff-shell model. For the ischemic model, the eigenfrequency was between those of the soft-and stiff-shell models. This result implies that inhomogeneity is an important factor in improving CEME.