Demonstration of left ventricular outflow tract eccentricity by real time 3D echocardiography: Implications for the determination of aortic valve area

Sanjay Doddamani, Ricardo Bello, Mark A. Friedman, Anita Banerjee, James H. Bowers, Bette Kim, Prashant R. Vennalaganti, Robert J. Ostfeld, Garet M. Gordon, Divya Malhotra, Daniel M. Spevack

Research output: Contribution to journalArticle

107 Scopus citations

Abstract

Background: Determination of the left ventricular outflow tract cross-sectional area (ALVOT) is necessary for calculating aortic valve area (AVA) by echocardiography using the continuity equation (CE). In the commonly applied form of CE, πr2 is used to estimate ALVOT utilizing the assumptions that LVOT is round and the parasternal long axis (PLAX) plane bisects LVOT. Imaging LVOT using real time 3D echocardiography (RT3DE) eliminates the need for these assumptions. We tested the hypothesis that LVOT is round based on a formula for eccentricity. Methods and Results: In 53 patients, 2D echocardiography (2DE) and RT3DE were acquired. ALVOT was calculated by 2DE using πr2 (ALVOT-2D). Using RT3DE, ALVOT planimetry was performed immediately beneath the aortic valve (ALVOT-3Dplan). Eccentricity Index (EI) was calculated using the shortest and longest LVOT diameters. The long axis was measured to be larger by 0.53 cm ± 0.36 (P < 0.005). The median EI was 0.20 (0.00-0.54), indicating that half the subjects had at least a 20% difference between the major and minor diameters. ALVOT-3Dplan was larger than ALVOT-2D (3.73 ± 0.95 cm2 vs. 3.18 ± 0.73 cm 2; P < 0.001) by paired analysis. Using the equation of an ellipse (πab), ALVOT-3Dellip was 3.57 ± 0.95 resulting in improved agreement with ALVOT-3Dplan. Conclusions: In our small patient sample with normal aortic valves, we showed the LVOT shape is usually not round and frequently, elliptical. Incorrectly assuming a round LVOT underestimated the ALVOT-3Dplan and consequently the AVA by 15%. Investigating the LVOT in aortic stenosis is warranted to evaluate whether RT3DE may improve measurement of AVA.

Original languageEnglish (US)
Pages (from-to)860-866
Number of pages7
JournalEchocardiography
Volume24
Issue number8
DOIs
StatePublished - Sep 1 2007

Keywords

  • Aortic valve area
  • Continuity equation
  • Left ventricular outflow tract
  • Real time 3D echocardiography

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Cardiology and Cardiovascular Medicine

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    Doddamani, S., Bello, R., Friedman, M. A., Banerjee, A., Bowers, J. H., Kim, B., Vennalaganti, P. R., Ostfeld, R. J., Gordon, G. M., Malhotra, D., & Spevack, D. M. (2007). Demonstration of left ventricular outflow tract eccentricity by real time 3D echocardiography: Implications for the determination of aortic valve area. Echocardiography, 24(8), 860-866. https://doi.org/10.1111/j.1540-8175.2007.00479.x