Blood Cell Adhesion on a Polymeric Heart Valve Leaflet Processed Using Magnetic Abrasive Finishing

Abstract

Polymeric heart valves have the potential to improve hemodynamic function without the complications associated with bioprosthetic and mechanical heart valves, but they have exhibited issues that need to be addressed including calcification, hydrolysis, low durability, and the adhesion of blood cells on the valves. These issues are attributed to the valves' material properties and surface conditions in addition to the hemodynamics. To overcome these issues, a new stentless, singlecomponent trileaflet polymeric heart valve with engineered leaflet surface texture was designed, and prototypes were fabricated from a simple polymeric tube. The singlecomponent structure features a trileaflet polymeric valve and conduit that are made of a single tube component to eliminate complications possibly caused by the interaction of multiple materials and components. This paper focuses on the leaflet surface modification and the effects of leaflet surface texture on blood cell adhesion to the leaflet surface. Silicone rubber was chosen as the working material. A magnetic abrasive finishing (MAF) process was used to alter the inner surface of the tubular mold in contact with the silicone leaflets during the curing process. It was hypothesized that the maximum profile height Rz of the mold surface should be smaller than the minimum platelet size of 1 خ¼m to prevent platelets (1–3 خ¼m in diameter) from becoming lodged between the peaks. Cell adhesion studies using human whole blood flushed at low shear stresses over leaflet surfaces with six different textures showed that adhesion of the platelets and red blood cells is greatly influenced by both surface roughness and lay. Leaflets replicated from MAFproduced mold surfaces consisting of short asperities smaller than 1 خ¼m reduced blood cell adhesion and aggregation. Cell adhesion studies also found that either mold or leaflet surface roughness can be used as a measure of cell adhesion.