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You are here: Contents > 2014 > Volume 23 Number 3 May 2014 > AORTIC VALVE DISEASE > Quantification of Low-Gradient Severe Aortic Stenosis Using a Hybrid Approach Combining Doppler Echocardiography and Thermodilution

Quantification of Low-Gradient Severe Aortic Stenosis Using a Hybrid Approach Combining Doppler Echocardiography and Thermodilution

Philippe Unger1, Chantal Dedobbeleer2, Eric Stoupel1, Nicolas Preumont2, Jean-François Argacha3, Guy Berkenboom2, Guy Van Camp3

1Université Libre de Bruxelles-Centre Hospitalier Universitaire Saint-Pierre, Brussels, 2Erasme Hospital, Brussels, 3Universitair Ziekenhuis Brussel-Vrije Universiteit Brussel, Brussels, Belgium

Background and aim of the study: Estimation of stroke volume in the left ventricular outflow tract (LVOT) is a main limitation to aortic valve area (AVA) calculation by echocardiography when using the continuity equation. In this study, the hypothesis was tested that a hybrid method using thermodilution-derived cardiac output measurement and simultaneous Doppler estimation of the systolic ejection period and transvalvular aortic velocities could be used to accurately assess AVA in patients with low-gradient severe aortic stenosis (AS).

Methods: Eighteen patients with low mean gradient (<40 mmHg) and nine patients with conventionally defined (≥40 mmHg) severe AS (<1 cm2), as assessed by the echocardiographic continuity equation (baseline echocardiography), underwent catheterization and simultaneous Doppler recording of trans-aortic velocities.

Results: The mean pressure gradient was slightly lower by

Doppler in the catheterization laboratory (35.8 ± 15.7 mmHg) compared to baseline echocardiography (37.4 ± 15.2 mmHg) and invasive (38.5 ± 16.6 mmHg) measurements (both p <0.05). The AVA values were 0.72 ± 0.12 cm2 during baseline echocardiography, 0.74 ± 0.14 cm2 by catheterization, and 0.71 ± 0.14 cm2 by the hybrid method (bias -0.01 ± 0.11 cm2 and -0.02 ± 0.08 cm2, versus echocardiography and catheterization, respectively; both p = NS).

Conclusion: The hybrid method is reasonably accurate in assessing AVA in patients with lowgradient severe AS. Although the continuity equation should be used in routine clinical practice in most patients, this method could serve as an alternative when the LVOT diameter and/or velocities seem questionable.

The Journal of Heart Valve Disease 2014;23:271-278

Quantification of Low-Gradient Severe Aortic Stenosis Using a Hybrid Approach Combining Doppler Echocardiography and Thermodilution

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