Prediction of Lipid Uptake by Prosthetic Heart Valve Poppets from Solubility Parameters

Abstract

Most prosthetic heart valves currently implanted consist of a silicone rubber poppet situated within a metallic cage. Recent reports indicate that gradual deterioration of the poppet can occur and lead to serious valve malfunction. Physical changes (variance) observed in recovered prosthesis include discoloration, swelling, and cracking. A major cause of variance is believed to be lipid accumulation. This article presents an assessment of the solubility of lipids in silicone rubber and other commonly used poppet materials. The analysis is based on solubility parameter theory that is based on principles derived from thermodynamic considerations. The results of this analysis predict that highly polar compounds, such as phospholipids or proteins, should not be present in silicone rubber poppets, which is in agreement with observations.