To evaluate possible causes of discrepancy between Doppler and catheter gradients across prosthetic valves, five sizes (19-27 mm) of St. Jude and Hancock valves were studied in an aortic pulsatile flow model. Catheter gradients at multiple sites distal to the valve were compared with simultaneously obtained Doppler gradients. In the St. Jude valve, significant differences between Doppler and ca...
