title: Effect of the ellipsoid shape of the left ventricular outflow tract on the echocardiographic assessment of aortic valve area in aortic stenosis.
abstract: 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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Radiology, Cardiac CT/MR Unit, Rouen University Hospital, 1 rue de Germont, 76031 Rouen, France.
authors.forename: Clément
authors.initials: C
authors.lastname: De Vecchi
authors.affiliation: Department of Radiology, Cardiac CT/MR Unit, Rouen University Hospital, 1 rue de Germont, 76031 Rouen, France; Inserm U1096, Rouen, France; University of Rouen, Institute for Research and Innovation in Biomedicine, Rouen, France. Electronic address: Jerome.Caudron@chu-rouen.fr.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Caudron
authors.affiliation: Department of Radiology, Cardiac CT/MR Unit, Rouen University Hospital, 1 rue de Germont, 76031 Rouen, France; Inserm U1096, Rouen, France; University of Rouen, Institute for Research and Innovation in Biomedicine, Rouen, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Dubourg
authors.affiliation: Department of Radiology, Cardiac CT/MR Unit, Rouen University Hospital, 1 rue de Germont, 76031 Rouen, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Pirot
authors.affiliation: Department of Radiology, Cardiac CT/MR Unit, Rouen University Hospital, 1 rue de Germont, 76031 Rouen, France; Inserm U1096, Rouen, France; University of Rouen, Institute for Research and Innovation in Biomedicine, Rouen, France.
authors.forename: Valentin
authors.initials: V
authors.lastname: Lefebvre
authors.affiliation: Inserm U1096, Rouen, France; University of Rouen, Institute for Research and Innovation in Biomedicine, Rouen, France; Department of Cardiology, Rouen University Hospital, Rouen, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Bauer
authors.affiliation: Inserm U1096, Rouen, France; University of Rouen, Institute for Research and Innovation in Biomedicine, Rouen, France; Department of Cardiology, Rouen University Hospital, Rouen, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Eltchaninoff
authors.affiliation: Department of Radiology, Cardiac CT/MR Unit, Rouen University Hospital, 1 rue de Germont, 76031 Rouen, France; Inserm U1096, Rouen, France; University of Rouen, Institute for Research and Innovation in Biomedicine, Rouen, France.
authors.forename: Jean-Nicolas
authors.initials: JN
authors.lastname: Dacher
mesh_terms: D000369:Aged, 80 and over; D001021:Aortic Valve / Q000000981:diagnostic imaging*; D001024:Aortic Valve Stenosis / Q000150:complications* / Q000000981:diagnostic imaging*; D004452:Echocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D061330:Multidetector Computed Tomography / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014694:Ventricular Outflow Obstruction / Q000000981:diagnostic imaging* / Q000209:etiology*
keywords: Aortic stenosis; Continuity equation; Left ventricular outflow tract; MDCT; Transthoracic echocardiography