In vitro evaluation of Doppler pressure gradient

Evaluation of prosthetic heart valves using Doppler echocardiography remains still controversial although Doppler technique has become standardized for assessing native heart valve function. One of the reasons is the discrepancy between Doppler and catheter gradient due to pressure recovery. This threshold can be overcome by in vitro standardization effects because both gradients are coupled by /spl Delta/p/sub doppler/=8g/K /spl Delta/p/sub catheter/ with K pressure loss coefficient dependent on prosthetic valve geometry and g gravitational acceleration. The authors try to give some clarification in this matter.<>