Doppler ultrasound accurately estimated pressure gradients across irregular and dual stenoses (r=0.97-0.99), but underestimated gradients in long, narrow tunnellike obstructions by up to 42%.
Does Doppler ultrasound accurately estimate pressure gradients across irregular, dual, and tunnellike obstructions compared to direct-pressure manometer in an in vitro model?
Doppler ultrasound accurately estimates pressure gradients across irregular and dual orifices but significantly underestimates gradients in long, narrow tunnellike obstructions.
Effect estimate: r = 0.97 to 0.99
The accuracy of Doppler-estimated pressure gradients in the setting of irregular, multiple, and tunnellike stenoses was investigated. An in vitro model of the left ventricular outflow tract was designed to allow pulsatile flow of red cells in saline across valve orifices from 0.01 to 2.5 cm2. Simultaneous pressure gradients were estimated by both Doppler and direct-pressure manometer techniques. Gradients obtained by the two methods correlated well for valve areas in the range of clinical stenoses at pressure gradients of 10 to 150 mm Hg (r = .97 to .99). Model valves were constructed with a large orifice (0.75 to 1.25 cm2) placed beside a small orifice (0.02 to 0.25 cm2) in the same outflow tract. A distinct jet was recorded when the Doppler transducer was aligned with each orifice. Doppler-estimated gradients for each pair of large and small orifices were identical and correlated well with those measured by manometer (r = .97 to .99). Irregularly shaped orifices also provided good correlation between the two methods (r = .98 to .99). Pulsatile flow was generated through long tunnellike obstructions with cross-sectional areas varying from 0.06 to 1.25 cm2. Tunnel length varied from 0.1 to 4 cm. Tunnel areas above 0.25 cm2 gave good Doppler-to-manometer correspondence at all tunnel lengths. Doppler underestimated manometer-determined values in the 0.25 cm2 tunnel by 8% at 3 cm and by 15% at 4 cm. In the 0.06 cm2 tunnel, Doppler underestimated manometer gradients by 12%, 15%, 32%, and 42% at lengths of 1, 2, 3, and 4 cm, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Teirstein et al. (1985) studied Left ventricular outflow tract obstructions (irregular, multiple, and tunnellike stenoses). Doppler ultrasound measurement vs. Direct-pressure manometer techniques was evaluated on Pressure gradients (r = 0.97 to 0.99). Doppler ultrasound accurately estimated pressure gradients across irregular and dual stenoses (r=0.97-0.99), but underestimated gradients in long, narrow tunnellike obstructions by up to 42%.