close
Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2008 Oct;29(20):2526-35.
doi: 10.1093/eurheartj/ehn022. Epub 2008 Feb 9.

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

Kian Keong Poh  1 , Robert A Levine, Jorge Solis, Liang Shen, Mary Flaherty, Yue-Jian Kang, J Luis Guerrero, Judy Hung
Affiliations

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

Kian Keong Poh et al. Eur Heart J. 2008 Oct.

Abstract

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.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Epicardial echocardiograms of a sheep at the apical three-chamber window showing balloon inflation of the left ventricular (LV) septum at the LV outflow tract (OT), mimicking clinical upper septal hypertrophy and distorting the LVOT geometry (left panel). Colour Doppler revealed non-uniform flow across the LVOT (right panel). RV, right ventricle; Ao, Aorta.
Figure 2
Figure 2
(A and B) Three-dimensional projections showing colour Doppler filling the LVOT. Sampling curve captured velocity vectors perpendicular to the hemispheric concave surface. (C) Region of interest was traced and the Tomtek software automatically calculated the forward flow in systole over time. (D) Derivation of stroke volume (SV) was obtained by integration of area under the flow-vs.-time curve. Cardiac output was calculated from the product of SV and heart rate.
Figure 3
Figure 3
Real-time three-dimensional echocardiographic aortic valve area (AVA) by planimetry. Cropping allows alignment of short-axis plane (B and C) at the narrowest orifice as visualized in long axis plane (A). Arrows point to the aortic valve leaflets in systole. Cropping planes are shown in 3D set for reference (D). LV, left ventricle; Ao, Ascending Aorta.
Figure 4
Figure 4
Scatter plot of correlation between aortic valve area calculated from two-dimensional echocardiography derived continuity equation [AVA(2D)] and that obtained from real-time three-dimensional stroke volume quantification [AVA(3D-SV)]. Dashed lines represent 95% prediction band of the regression line.
Figure 5
Figure 5
Bland–Altman analysis showing better agreement between aortic valve area calculated from three-dimensional continuity [AVA(3D-SV)] and three-dimensional planimetry (AVA(3D-Pl) (on the right panel) than that between aortic valve area from two-dimensional continuity [AVA(2D)] and planimetered area (left panel). Dashed lines represent ±2SD from the mean.
Figure 6
Figure 6
Two-dimensional echocardiography at the parasternal long-axis view illustrating how upper septal hypertrophy distorting the left ventricular outflow tract geometry might lead to erroneous and wide variation of aortic valve area (AVA) calculation by two-dimensional continuity equation. LV, left ventricle; Ao, Aorta.
Figure 7
Figure 7
Correlations between the left ventricular outflow tract (LVOT) cardiac output (CO) derived from two-dimensional echocardiography (2DE) Doppler (left panel) and three-dimensional echocardiography (3DE) colour Doppler (right panel) vs. the referenced flow probe measurements. These were obtained from sheep models with distorted LVOT geometry.
Figure 8
Figure 8
Bland–Altman plots of the cardiac output (CO) measurements by two-dimensional echocardiography (2DE) with flow probe measurements (left panel) and that of three-dimensional echocardiography (3DE) with flow probe CO (right panel). Dashed lines represent ±2SD from the mean.
See this image and copyright information in PMC

References

    1. Bonow RO, Carabello B, de Leon AC, Edmunds LH, Jr, Fedderly BJ, Freed MD, Gaasch WH, McKay CR, Nishimura RA, O'Gara PT, O'Rourke RA, Rahimtoola SH, Ritchie JL, Cheitlin MD, Eagle KA, Gardner TJ, Garson A, Jr, Gibbons RJ, Russell RO, Ryan TJ, Smith SC., Jr 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) J Heart Valve Dis. 1998;7:672–707. - PubMed
    1. Skjaerpe T, Hegrenaes L, Hatle L. Noninvasive estimation of valve area in patients with aortic stenosis by Doppler ultrasound and two-dimensional echocardiography. Circulation. 1985;72:810–818. - PubMed
    1. Otto CM, Pearlman AS, Comess KA, Reamer RP, Janko CL, Huntsman LL. Determination of the stenotic aortic valve area in adults using Doppler echocardiography. J Am Coll Cardiol. 1986;7:509–517. - PubMed
    1. Zoghbi WA, Farmer KL, Soto JG, Nelson JG, Quinones MA. Accurate noninvasive quantification of stenotic aortic valve area by Doppler echocardiography. Circulation. 1986;73:452–459. - PubMed
    1. Pemberton J, Li X, Karamlou T, Sandquist CA, Thiele K, Shen I, Ungerleider RM, Kenny A, Sahn DJ. The use of live three-dimensional Doppler echocardiography in the measurement of cardiac output: an in vivo animal study. J Am Coll Cardiol. 2005;45:433–438. - PubMed

Publication types