Prevention of polyurethane valve cusp calcification with covalently attached bisphosphonate diethylamino moieties.

Objective: Calcification of polyurethane prosthetic valve leaflets causes a major functional impairment. Previously we showed that polyurethane heart valves modified with covalently linked bisphosphonate groups were resistant to calcification in vivo. However, we also found that the highly polar anionic bisphosphonate groups on the polyurethane surface attracted sodium counter ion adsorption, and thereby increased the elastomer's water absorption to 20% of total weight.