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Accuracy and pitfalls of Doppler evaluation of the pressure gradient in aortic coarctation
Insights
Doppler echocardiography accurately estimates pressure gradients in aortic coarctation. Including pre- and post-obstruction velocities improves accuracy, offering a reliable alternative to traditional methods when sphygmomanometry is not feasible.
Area of Science:
- Cardiology
- Medical Imaging
- Pediatric Cardiology
Background:
- Accurate pressure gradient measurement in aortic coarctation is crucial for diagnosis and management.
- Sphygmomanometry can be unreliable in certain patients due to limb arterial compromise.
- Non-invasive methods are needed to reliably assess transcoarctation pressure gradients.
Purpose of the Study:
- To evaluate the accuracy of Doppler echocardiography in predicting pressure gradients across coarctation of the aorta.
- To compare Doppler-derived gradients with those obtained via cardiac catheterization.
- To determine if incorporating proximal velocities improves Doppler gradient estimation.
Main Methods:
- A systematic review and meta-analysis of 32 studies comparing Doppler echocardiography with cardiac catheterization for aortic coarctation.
- Doppler-derived transcoarctation gradients were calculated using the modified Bernoulli equation with jet velocities.
- Analysis included methods using only distal velocities (V2) and those incorporating proximal (V1) and distal (V2) velocities.
Main Results:
- Doppler echocardiography closely estimated catheterization-derived pressure gradients (r = 0.91).
- When both proximal and distal velocities were used, Doppler estimation significantly improved, closely matching catheterization gradients (r = 0.98).
- The mean Doppler-estimated gradient using V1 and V2 was 36 +/- 20 mm Hg, compared to 36 +/- 21 mm Hg by catheterization.
Conclusions:
- Doppler echocardiography is a reliable non-invasive tool for estimating pressure gradients in aortic coarctation.
- Including velocities proximal and distal to the obstruction in the modified Bernoulli equation enhances the accuracy of Doppler gradient assessment.
- This method provides a valuable alternative when sphygmomanometry is compromised.
Abstract:
Although the pressure gradient in aortic coarctation can usually be obtained by comparison of upper and lower limb blood pressures measured by sphygmomanometry, some patients may have upper or lower limb arterial compromise as a result of prior procedures or anomalous origin of the subclavian arteries, either of which may preclude accurate gradient measurement. To determine whether Doppler echocardiography could predict the pressure gradient, the Doppler method was used to predict transcoarctation gradients in 35 studies and the data were compared with the gradients measured at catheterization. Jet velocities were not adequately obtained by Doppler recording in three neonates with coarctation and patent ductus arteriosus, leaving 32 studies for analysis. The mean age of the study patients was 6 +/- 5.8 years. The mean Doppler-estimated gradient, calculated using only jet velocities distal to the obstruction (V2) in the modified Bernoulli equation, was 44 +/- 17 mm Hg, and the mean catheterization gradient was 36 +/- 21 mm Hg (p = NS; r = 0.91, SEE = 7.0 mm Hg; slope = 0.75, y = 17.3 mm Hg). The mean Doppler-estimated gradient using both the pre- and postcoarctation velocities (V1 and V2) in the modified Bernoulli equation (n = 26) was 36 +/- 20 mm Hg, and the mean catheterization gradient was 36 +/- 21 mm Hg (p = NS; r = 0.98, SEE = 4.2 mm Hg; slope = 0.91, y = 2.8 mm Hg). Doppler echocardiography closely estimated the pressure gradient in aortic coarctation, and estimation of the gradient improved when the velocities proximal as well as distal to the obstruction were included in the modified Bernoulli equation.