Red cell damage in flexible leaflet heart valves

A pyrolytic carbon (rigid) bileaflet mechanical valve and an ultra high molecular weight polyethylene (UHMPE-flexible) tilting disc valve were used in the study in an in vitro pulsatile flow loop. Fresh bovine blood was used as the blood analog fluid and plasma free hemoglobin (PFHg: a measure of hemolysis) measured at 15 min intervals, normalized to magnitude at the start of the experiment was used as an index for blood damage. The negative pressure transients in the atrial side of the chamber were also measured. The mean and standard deviations of eight valves in each category were computed. The blood losses as well. As the negative pressure transients with the flexible leaflet valve were significantly lower compared to the rigid leaflet valve. The flexibility of the leaflet, and the reduction in water hammer effect at the instant of valve closure results in reduced damage to blood cells and may be an important factor in mechanical valve design