Development of BioPoly® materials for use in prosthetic heart valve replacements
Date
2012
Authors
Dean, Harold, author
James, Sue, advisor
Dasi, Prasad, committee member
Orton, Chris, committee member
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Abstract
Since their conception in the 1950s, prosthetic heart valves (HV) have suffered clinical complications. Mechanical HVs, made from synthetic materials and with unnatural hemodynamics, are prone to thrombus formation without anti-coagulation therapy. Bioprosthetic HVs, made from fixed natural tissues, do not generally elicit thrombogenicity, but require long-term antiplatelet therapy and have a shorter lifespan due to calcification and tearing. Polymeric and fabric leaflet HVs potentially have the durability of a mechanical HV with the natural hemodynamics of a bioprosthetic valve; however, previous polymeric leaflet HVs did have problems with thrombus formation and calcification and very little research has been done on fabric leaflet HVs. This research aimed to explore the possibility to improve the hemocompatibility and long term in vivo performance of polymeric and fabric HV leaflets by improving polymer surface chemistry. The overall goal of the current project was to develop BioPoly materials for cardiovascular applications. The percent crystallinity, mechanical properties (i.e. tensile and bending), surface contact angle and hemocompatibility with whole blood of hyaluronan (HA) treated linear low density polyethylene (LLDPE) film and polyethylene terephtalate (PET) fabric were compared to untreated LLDPE film and PET fabric. Both processes were successful in incorporating HA into the base polymer structures. The swelling method used with the LLDPE allowed for HA concentrations ranging from 0.5% to 1.5%. The open weave of the PET fabric resulted in more controllable HA integration with a range from 0.25% to 3.5% HA. The process used to integrate HA maintained original tensile and bending properties and reduced surface water contact angle compared to LLDPE controls (86.7±2.3° to 39.0±1.1°). Increasing HA content did not further reduce contact angle when the additional surface dip was utilized. Whole blood clotting was significantly less on the HA-treated materials than the control LLDPE and PET, with clotting becoming negligible at the higher HA concentrations, as confirmed by free hemoglobin and scanning electron microscopy (SEM). The reduction of contact angle in the HA-treated LLDPE indicates the hydrophilic nature of the composite which resulted in better anti-thrombogenic properties.
Description
Rights Access
Subject
heart valve
thrombus
polyethylene
hemocompatible