Assessing aortic valve area in aortic stenosis by continuity equation: a novel approach using real-time three-dimensional echocardiography.

AIMS Two-dimensional echocardiographic (2DE) continuity-equation derived aortic valve area (AVA) in aortic stenosis (AS) relies on non-simultaneous measurement of left ventricular outflow tract (LVOT) velocity and geometric assumptions of LVOT area, which can amplify error, especially in upper septal hypertrophy (USH). We hypothesized that real-time three-dimensional echocardiography (RT3DE) can improve accuracy of AVA by directly measuring LVOT stroke volume (SV) in one window. METHODS AND RESULTS RT3DE colour Doppler and 2DE were acquired in 68 AS patients (74 +/- 12 yrs) prospectively. SV was derived from flow obtained from a sampling curve placed orthogonal to LVOT (Tomtec Imaging). Agreement between continuity-equation derived AVA by RT3DE (AVA(3D-SV)) and 2DE (AVA(2D)) and predictors of discrepancies were analysed. Validation of LVOT SV was performed by aortic flow probe in a sheep model with balloon inflation of septum to mimic USH. There was only modest correlation between AVA(2D) and AVA(3D-SV) (r = 0.71, difference 0.11 +/- 0.23 cm(2)). The degree of USH was significantly associated with difference in AVA calculation (r = 0.4, P = 0.005). In experimentally distorted LVOT geometry in sheep, RT3DE correlated better with flow probe assessment (r = 0.96, P < 0.001) than 2DE (r = 0.71, P = 0.006). CONCLUSION RT3DE colour Doppler-derived LVOT SV in the calculation of AVA by continuity equation is more accurate than 2D, including in situations such as USH, common in the elderly, which modify LVOT geometry.

[1]  M. Quiñones,et al.  Accurate noninvasive quantification of stenotic aortic valve area by Doppler echocardiography. , 1986, Circulation.

[2]  M Jones,et al.  Real-time three-dimensional echocardiography for measurement of left ventricular volumes. , 1999, The American journal of cardiology.

[3]  H. Torp,et al.  Cross-sectional left ventricular outflow tract velocities before and after aortic valve replacement: a comparative study with two-dimensional Doppler ultrasound. , 1993, Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography.

[4]  A. Cohen-Solal,et al.  Diagnosis of aortic valvular stenosis by multislice cardiac computed tomography. , 2006, European heart journal.

[5]  A. Weyman,et al.  Aortic stenosis: physics and physiology--what do the numbers really mean? , 2005, Reviews in cardiovascular medicine.

[6]  H. Baumgartner,et al.  Determination of aortic valve area by Doppler echocardiography using the continuity equation: a critical evaluation. , 1990, Cardiology.

[7]  R. Baumann,et al.  Use of 3-dimensional color Doppler echocardiography to measure stroke volume in human beings: comparison with thermodilution. , 2007, Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography.

[8]  C. Otto,et al.  Recommendations for quantification of Doppler echocardiography: a report from the Doppler Quantification Task Force of the Nomenclature and Standards Committee of the American Society of Echocardiography. , 2002, Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography.

[9]  M. Spiecker,et al.  Quantitative assessment of aortic stenosis by three-dimensional echocardiography. , 1997, Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography.

[10]  J. Scheiman.  Strategies to reduce the GI risks of antiplatelet therapy. , 2005, Reviews in cardiovascular medicine.

[11]  N. Nanda,et al.  Images in geriatric cardiology. Usefulness of live three-dimensional transthoracic echocardiography in aortic valve stenosis evaluation. , 2004, The American journal of geriatric cardiology.

[12]  K Matre,et al.  Three-dimensional cross-sectional velocity distribution in the ascending aorta in cardiac patients. , 1996, Clinical physiology.

[13]  Michael Jerosch-Herold,et al.  Real-time three-dimensional color Doppler echocardiography overcomes the inaccuracies of spectral Doppler for stroke volume calculation. , 2006, Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography.

[14]  B. Mégarbane,et al.  Comparison of cardiac output measured with echocardiographic volumes and aortic Doppler methods during mechanical ventilation , 2003, Intensive Care Medicine.

[15]  Bjørn Olav Haugen,et al.  Blood flow velocity profiles in the aortic annulus: a 3-dimensional freehand color flow Doppler imaging study. , 2002, Journal of the American Society of Echocardiography.

[16]  K. Thiele,et al.  The use of live three-dimensional Doppler echocardiography in the measurement of cardiac output: an in vivo animal study. , 2005, Journal of the American College of Cardiology.

[17]  Hemodynamic assessment of aortic stenosis: are there still lessons to learn? , 2006, Journal of the American College of Cardiology.

[18]  J. Fleiss,et al.  Intraclass correlations: uses in assessing rater reliability. , 1979, Psychological bulletin.

[19]  D. Altman,et al.  STATISTICAL METHODS FOR ASSESSING AGREEMENT BETWEEN TWO METHODS OF CLINICAL MEASUREMENT , 1986, The Lancet.

[20]  F. Laurent,et al.  Absolute assessment of aortic valve stenosis by planimetry using cardiovascular magnetic resonance imaging: comparison with transesophageal echocardiography, transthoracic echocardiography, and cardiac catheterisation. , 2006, European journal of radiology.

[21]  L L Huntsman,et al.  Determination of the stenotic aortic valve area in adults using Doppler echocardiography. , 1986, Journal of the American College of Cardiology.

[22]  R. Gibbons,et al.  ACC/AHA Guidelines for the Management of Patients With Valvular Heart Disease. Executive Summary. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Patients With Valvular Heart Disease). , 1998, The Journal of heart valve disease.

[23]  L Hatle,et al.  DIAGNOSTIC METHODS , 2005 .

[24]  Xiaokui Li,et al.  Real-time 3-dimensional Doppler echocardiography for the assessment of stroke volume: an in vivo human study compared with standard 2-dimensional echocardiography. , 2005, Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography.

[25]  H. Torp,et al.  The velocity distribution in the aortic anulus in normal subjects: a quantitative analysis of two-dimensional Doppler flow maps. , 1991, Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography.

[26]  T. Abraham,et al.  Three-dimensional surface area of the aortic valve orifice by three-dimensional echocardiography: clinical validation of a novel index for assessment of aortic stenosis. , 1998, American heart journal.

[27]  Damien Garcia,et al.  What do you mean by aortic valve area: geometric orifice area, effective orifice area, or gorlin area? , 2006, The Journal of heart valve disease.

[28]  Robert A Levine,et al.  Effect of three-dimensional valve shape on the hemodynamics of aortic stenosis: three-dimensional echocardiographic stereolithography and patient studies. , 2002, Journal of the American College of Cardiology.

[29]  R. Shandas,et al.  Analysis of the effect of flow rate on the Doppler continuity equation for stenotic orifice area calculations: a numerical study. , 1998, Circulation.

[30]  Louis-Gilles Durand,et al.  Flow-dependent changes in Doppler-derived aortic valve effective orifice area are real and not due to artifact. , 2006, Journal of the American College of Cardiology.

[31]  D. Sahn,et al.  Surface integration of velocity vectors from 3D digital colour Doppler: an angle independent method for laminar flow measurements. , 2002, European journal of echocardiography : the journal of the Working Group on Echocardiography of the European Society of Cardiology.