In vitro evaluation of forward and reverse volumetric flow across a regurgitant aortic valve using Doppler power-weighted mean velocities.
To determine the accuracy of using power-weighted mean velocities for quantitating volumetric flow across a cardiac valve, we equipped pulsatile flow-tank systems with a 25 mm porcine or a 27 mm mechanical valve with various sizes of regurgitant orifices. Forward and reverse volumetric flows were measured over a range of hemodynamic conditions using two insonating angles (0 and 45 degrees). Pulsed Doppler power-weighted mean velocity measurements were obtained simultaneously with electromagnetic or ultrasonic transit-time probe measurements. For the porcine valve, Doppler measurements correlated well with electromagnetic flow measurements for all (r = 0.75 to 0.97, p < 0.05) except the smallest (2.7 mm) orifice (r = 0.19). For the mechanical valve, power-weighted mean velocity measurements correlated well with ultrasonic transit-time measurements for each hemodynamic condition defined by pulse rate, mean arterial pressure, and insonating angle (r = 0.93 to 0.99, p < 0.01), but equations varied unpredictably. Thus, although power-weighted mean velocity volumetric flow measurements correlate well with flow probe measurements, equations vary widely as hemodynamic conditions change. Because of this variation, power-weighted mean velocity data are not useful for quantitation of volumetric flow across a cardiac valve at this time. Further investigation may show how different hemodynamic conditions affect power-weighted mean velocity measurements of volumetric flow.
Minich
L L
LL
Department of Pediatrics, Primary Children's Medical Center, Salt Lake City, UT 84113, USA.
Tani
L Y
LY
Pantalos
G M
GM
D001022:Aortic Valve Insufficiency / Q000601:surgery*; D001705:Bioprosthesis; D001783:Blood Flow Velocity; D001810:Blood Volume / Q000502:physiology*; D018619:Echocardiography, Doppler, Pulsed; D006439:Hemodynamics; D018056:Hemorheology; D016014:Linear Models