Effect of the ellipsoid shape of the left ventricular outflow tract on the echocardiographic assessment of aortic valve area in aortic stenosis

J Cardiovasc Comput Tomogr. 2014 Jan-Feb;8(1):52-7. doi: 10.1016/j.jcct.2013.12.006. Epub 2014 Jan 11.


Background: Previous studies showed discrepancies between echocardiographic and multidector row CT (MDCT) measurements of aortic valve area (AVA).

Objective: Our aim was to evaluate the effect of the ellipsoid shape of the left ventricular outflow tract (LVOT), as shown and measured by MDCT, on the assessment of AVA by transthoracic echocardiography (TTE) in patients with severe aortic stenosis.

Methods: This retrospective single-center study involved 49 patients with severe aortic stenosis referred before transcatheter aortic valve implantation. The AVA was deduced from the continuity equation on TTE and from planimetry on cardiac MDCT. Area of the LVOT was calculated as follows: on TTE, from the measurement of LVOT diameter on parasternal long-axis view; on MDCT, from manual planimetry by using multiplanar reconstruction perpendicular to LVOT.

Results: At baseline, correlation of TTE vs MDCT AVA measurements was moderate (R = 0.622; P < .001). TTE underestimated AVA compared with MDCT (0.66 ± 0.15 cm2 vs. 0.87 ± 0.15 cm2; P < .001). After correcting the continuity equation with the LVOT area as measured by MDCT, mean AVA drawn from TTE did not differ from MDCT (0.86 ± 0.2 cm2) and correlation between TTE and MDCT measurements increased (R = 0.704; P < .001).

Conclusion: Assuming that LVOT area is circular with TTE results in constant underestimation of the AVA with the continuity equation compared with MDCT planimetry. The elliptical not circular shape of LVOT largely explains these discrepancies.

Keywords: Aortic stenosis; Continuity equation; Left ventricular outflow tract; MDCT; Transthoracic echocardiography.

Publication types

  • Comparative Study

MeSH terms

  • Aged, 80 and over
  • Aortic Valve / diagnostic imaging*
  • Aortic Valve Stenosis / complications*
  • Aortic Valve Stenosis / diagnostic imaging*
  • Echocardiography / methods*
  • Female
  • Humans
  • Image Enhancement / methods
  • Image Interpretation, Computer-Assisted / methods
  • Male
  • Multidetector Computed Tomography / methods*
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Ventricular Outflow Obstruction / diagnostic imaging*
  • Ventricular Outflow Obstruction / etiology*