Response of a replicated human heart system to dynamic loading

The response of the human heart and attached major vasculature to rapid acceleration loading was studied by means of a non-pulsatile replica consisting of leotard fabric components. The system was designed to prevent leakage of water intended to simulate the blood present. This model was emplaced inside a rigid thorax and mounted on a moving cart, with sudden arrest produced by barrier impact. Large displacements of the ventricles and other attached vessels and pressures in the heart compartments were measured. Twelve impacts to the front, side, rear and at oblique incidence for a condition corresponding to the end of diastole were executed. The tests indicated that the strains in the right ventricle and the interchamber pressure were significant. Strains in the inferior vena cava were relatively high with lower values for the superior vena cava. Significant extensions were also observed in the brachiocephalic, left common carotid and left subclavian arteries. These findings qualitatively substantiate clinical experience for humans subjected to rapid non-invasive loading. A simple spring-mass system was used to model the dynamic response of the replicated heart unit. Predicted values were found to be in fair agreement with test data.