Bileaflet aortic valve prosthesis pivot geometry influences platelet secretion and anionic phospholipid exposure

The clinical histories of the Medtronic Parallel (MP) and St. Jude Medical (SJM) Standard valves suggest pivot geometry influences the thrombogenic ch aracteristics of bileaflet prostheses. This work studied the effects of var ious pivot geometries on markers of platelet damage in a controlled, in vit ro apparatus. The Medtronic Parallel valve, two St. Jude Medical valves, an d two demonstration prostheses were used to study the effects of bileaflet pivot design, gap width, and size on platelet secretion and anionic phospho lipid expression during leakage flow. A centrifugal pump was used to drive blood through a circuit containing a bileaflet prosthesis. Samples were tak en at set time intervals after the start of the pump. These samples were an alyzed by cell counting, flow cytometry, and enzyme-linked immunosorbant as say. No significant differences were observed in platelet secretion or anio nic phospholipid expression between experiments with the SJM 27 Standard re gular leaker, the SIM 20 regular leaker, and the MP 27 valves. Significant differences in platelet secretion and anionic phospholipid expression were observed between a SJM 27 Standard regular leaker and a SJM 27 high leaker valve. These studies suggest that leakage gap width within bileaflet valve pivots has a significant effect on platelet damage initiated by leakage flo w. (C) 2001 Biomedical Engineering Society.