Comparison between cardiovascular magnetic resonance and transthoracic doppler echocardiography for the estimation of effective orifice area in aortic stenosisReport as inadecuate




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Journal of Cardiovascular Magnetic Resonance

, 13:25

First Online: 28 April 2011Received: 20 November 2010Accepted: 28 April 2011

Abstract

BackgroundThe effective orifice area EOA estimated by transthoracic Doppler echocardiography TTE via the continuity equation is commonly used to determine the severity of aortic stenosis AS. However, there are often discrepancies between TTE-derived EOA and invasive indices of stenosis, thus raising uncertainty about actual definite severity. Cardiovascular magnetic resonance CMR has emerged as an alternative method for non-invasive estimation of valve EOA. The objective of this study was to assess the concordance between TTE and CMR for the estimation of valve EOA.

Methods and results31 patients with mild to severe AS EOA range: 0.72 to 1.73 cm and seven 7 healthy control subjects with normal transvalvular flow rate underwent TTE and velocity-encoded CMR. Valve EOA was calculated by the continuity equation. CMR revealed that the left ventricular outflow tract LVOT cross-section is typically oval and not circular. As a consequence, TTE underestimated the LVOT cross-sectional area ALVOT, 3.84 ± 0.80 cm compared to CMR 4.78 ± 1.05 cm. On the other hand, TTE overestimated the LVOT velocity-time integral VTILVOT: 21 ± 4 vs. 15 ± 4 cm. Good concordance was observed between TTE and CMR for estimation of aortic jet VTI 61 ± 22 vs. 57 ± 20 cm. Overall, there was a good correlation and concordance between TTE-derived and CMR-derived EOAs 1.53 ± 0.67 vs. 1.59 ± 0.73 cm, r = 0.92, bias = 0.06 ± 0.29 cm. The intra- and inter- observer variability of TTE-derived EOA was 5 ± 5% and 9 ± 5%, respectively, compared to 2 ± 1% and 7 ± 5% for CMR-derived EOA.

ConclusionUnderestimation of ALVOT by TTE is compensated by overestimation of VTILVOT, thereby resulting in a good concordance between TTE and CMR for estimation of aortic valve EOA. CMR was associated with less intra- and inter- observer measurement variability compared to TTE. CMR provides a non-invasive and reliable alternative to Doppler-echocardiography for the quantification of AS severity.

Electronic supplementary materialThe online version of this article doi:10.1186-1532-429X-13-25 contains supplementary material, which is available to authorized users.

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Author: Julio Garcia - Lyes Kadem - Eric Larose - Marie-Annick Clavel - Philippe Pibarot

Source: https://link.springer.com/article/10.1186/1532-429X-13-25







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