Overestimation of flow velocity through leaks in mechanical valve prostheses and through small orifices by continuous-wave Doppler

Journal of the American Society of Echocardiography : Official Publication of the American Society of Echocardiography
F A FlachskampfP Hanrath

Abstract

The reliability of continuous-wave Doppler flow velocity measurements through small regurgitant lesions, such as in prosthetic leakage, has not been systematically analyzed. To evaluate the accuracy of continuous-wave Doppler in prosthetic valve leakage and small orifices in an in vitro, steady-flow model-flow velocities through the leaks of twelve intact mechanical prostheses and through six circular nozzles (area 0.5 to 20 mm2) were measured at pressure drops between 30 and 105 mm Hg. These results were compared with those predicted by the modified Bernoulli equation. Laser Doppler anemometry of flow velocities through the nozzles was also performed. Despite high correlation, there was substantial overestimation of Bernoulli predicted velocities by echo Doppler in the prosthetic leaks (mean +12.3% +/- 9.4%; range 90.3% to 143.4%). In the nozzles < or = 10 mm2, but not in the largest (20 mm2) nozzle, there was also overestimation of the Bernoulli predicted velocities (mean +6.2% +/- 2%). Laser Doppler anemometry of flow velocities through the nozzles showed slightly lower values than predicted by the Bernoulli equation. Thus, continuous-wave echo Doppler overestimates flow velocities through small orifices. This apparently is,...Continue Reading

References

Nov 15, 1991·Journal of the American College of Cardiology·F A FlachskampfJ D Thomas
May 1, 1984·The American Journal of Cardiology·J A RequarthH D Allen
Mar 1, 1980·British Heart Journal·L HatleA Tromsdal

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