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Limitations in assessing the severity of aortic stenosis by Doppler gradients
R Danielsen1, J E Nordrehaug, L Stangeland
1Department of Clinical Physiology, Haukeland Hospital, University of Bergen, Norway.
Insights
Doppler echocardiography underestimates aortic stenosis gradients, especially at high ranges. Transvalvar flow significantly impacts accuracy, limiting its use for severity assessment without considering flow rates.
Area of Science:
- Cardiovascular Medicine
- Diagnostic Imaging
- Echocardiography
Background:
- Aortic stenosis is a significant valvular heart disease.
- Echocardiography, particularly Doppler, is a primary non-invasive tool for assessing aortic stenosis severity.
- Accurate gradient measurement is crucial for clinical decision-making and patient management.
Purpose of the Study:
- To evaluate the agreement between Doppler echocardiography and cardiac catheterization-derived gradients in suspected aortic stenosis.
- To identify factors influencing discrepancies between Doppler and catheterization measurements.
- To assess the utility of Doppler gradients for determining aortic valve area and stenosis severity.
Main Methods:
- Continuous wave Doppler echocardiography performed prior to cardiac catheterization in 69 patients.
- Comparison of maximum and mean Doppler gradients with catheterization gradients.
- Stepwise regression analysis to identify influencing factors; correlation analysis with aortic valve area.
Main Results:
- Good agreement was observed between Doppler and catheterization gradients, but Doppler systematically underestimated values, particularly in high-gradient cases.
- Discrepancies were not explained by age, sex, stroke volume, heart rate, ejection fraction, coronary artery disease, or aortic regurgitation severity.
- A negative curvilinear correlation existed between Doppler gradients and aortic valve area in pure aortic stenosis, decreasing with concomitant aortic regurgitation; scatter was influenced by transvalvar flow.
Conclusions:
- Doppler echocardiography's accuracy in assessing aortic stenosis severity is limited by underestimation of gradients, especially at higher ranges.
- Transvalvar flow (low and high) significantly contributes to the variability and scatter of Doppler-derived gradients.
- The clinical utility of Doppler gradients for diagnosing and monitoring aortic stenosis is severely restricted unless transvalvar flow is considered.
Abstract:
Continuous wave Doppler echocardiography was performed before cardiac catheterisation in 69 consecutive patients with suspected aortic stenosis. Agreement between the maximum and the mean Doppler gradients and catheterisation gradients was good. Doppler echocardiography, however, systematically underestimated the maximum and mean gradients, particularly in the high range. Stepwise regression analysis of the small pressure difference between the two methods showed that it could not be explained by age, sex, stroke volume, differences in heart rate, ejection fraction, the presence of coronary artery disease, or severity of aortic regurgitation. There was a negative curvilinear correlation between the maximum and mean Doppler gradients and the aortic valve areas that were measured at catheterisation in patients with pure aortic stenosis. The degree of correlation decreased when patients with concomitant aortic regurgitation were included. The scatter of gradients above and below the correlation line was large and this was caused by low and high transvalvar flow. These results show that the usefulness of Doppler gradients for judging the severity of aortic stenosis, both in relation to immediate diagnosis and follow up, is severely limited if transvalvar flow is not taken into account.