Key result
Continuous wave Doppler consistently overestimates prosthetic valve pressure gradients versus manometry across all valve types.
Why the study?
The accuracy of continuous wave Doppler ultrasound in deriving pressure gradients across bioprosthetic heart valves needed evaluation across different valve types, sizes, and implantation statuses.
Does continuous wave Doppler ultrasound accurately measure pressure gradients across bioprosthetic aortic valves compared to manometric measurements in an in vitro model?
Does continuous wave Doppler ultrasound accurately measure pressure gradients across bioprosthetic aortic valves compared to manometric measurements in an in vitro model?
p-value: p=<0.0001
Continuous wave Doppler ultrasound consistently overestimates pressure gradients across bioprosthetic aortic valves in vitro, highlighting the need for clinical caution when interpreting these measurements.
Bench validation supports Doppler gradients for bioprosthetic valves; leaves open in vivo correlation and clinical adoption.
The accuracy of continuous wave Doppler ultrasound in deriving pressure gradients across bioprosthetic heart valves was evaluated in an in vitro pulse duplicator. Simultaneous pressure transducer and Doppler measurements were made in new and explanted aortic bioprosthetic valves of several sizes and four types: Carpentier-Edwards, Ionescu-Shiley, Hancock standard and Hancock modified. The mean and peak gradients calculated by the modified Bernoulli equation from Doppler velocity measurements were always greater than those measured manometrically, despite corrections for location dependence of the manometric gradient (or pressure recovery). The relation between manometric and ultrasonically determined gradient was found to be statistically dependent on the valve type (mean gradient p less than 0.0001; peak gradient p = 0.0003) and size (mean gradient p = 0.0089; peak gradient p = 0.0107). Effects of implantation were observed, but were not shown to be significant. It is concluded that the continuous wave Doppler velocity data overestimated prosthetic valve pressure gradient in all cases, even when pressure recovery was taken into account. Clinicians should be wary of Doppler data when making major diagnostic or therapeutic decisions.
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Stewart et al. (1991) studied Bioprosthetic aortic valves. Continuous wave Doppler ultrasound vs. Manometric pressure transducer measurements was evaluated on Mean and peak pressure gradients (p=<0.0001). Continuous wave Doppler ultrasound consistently overestimated prosthetic valve pressure gradients compared to manometric measurements across all valve types (mean gradient p<0.0001) and sizes.
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