Design of mold to yield elastomeric membrane whose shape and size, when inflated, is similar to the shape of the human heart

摘要

Nearly five million Americans are living with heart failure and 550,000 new cases are diagnosed each year in the US. Amongst the new approaches to develop a better solution for Congestive Heart Failure, Ventricular Recovery (VR) holds the most promise. A team, under the guidance of Dr. Criscione in the Cardiac Mechanics Lab at Texas A&M University, is currently developing an investigative device which aims to assist in VR by restoration of physiological strain patterns in the myocardial cells. The contribution of this thesis has been towards the development of a molding apparatus that yields a polymeric membrane whose shape, when inflated, is similar to the shape of the human heart. This membrane would surround the epicardial surface of the heart, when used for the device being discussed and in particular for the prototypes being developed. Contribution also includes a testing apparatus that measures the inflation of a membrane and simulation to predict the behavior of isotropic ellipsoids upon inflation. After unsuccessful implementations of two processing techniques, the successful design, fabrication implementation and attachment method meets the design criteria and is based on a thermoforming technique. Inflation profiles for membranes developed using this technique were studied at different pressures, with the axis length as variable. At 1kpa, which is the normal coronary arterial pressure, the membrane with an axis length of 140mm was found to show a shape which is similar to the shape of the human heart. In order to better understand and predict the shape an isotropic ellipsoidal membrane would take upon inflation without experimentation, simulations were carried out. Successful conversion of ellipsoidal geometry, with a few degrees of freedom as parameters, aided in simulation.