The osmotic swelling characteristics of cardiac valve prostheses

Several types of mechanical cardiac prostheses have been constructed with Delrin occluders, a material that is subject to osmotic swelling. The leaftets are designed to expand to specific tolerances when immersed in blood. The synthetic blood analogs commonly used in vitro contain hydrophilic compounds that can alter the osmotic expansion of the Delrin occluders. A static leak test chamber was employed to illustrate the effects of various test fluids on the sustained regurgitation phase of Delrin valves.