title: Differential left ventricular outflow tract remodeling and dynamics in aortic stenosis.
abstract: BACKGROUND
  Left ventricular outflow tract (LVOT) geometry is variable and often elliptical, which can affect aortic valve area calculation in patients with aortic stenosis (AS). Specific differences in LVOT geometry and dynamics between patients with AS and normal control subjects have not been described. The aim of this study was to test the hypothesis that differences in LVOT geometry in patients with AS might relate to variable LVOT remodeling and stiffness relative to normal control subjects.
  
  
  METHODS
  In 54 patients with severe AS and 33 control subjects without AS, LVOT geometry, dynamics, remodeling, and stiffness were assessed by three-dimensional transesophageal echocardiography. LVOT stiffness was measured by calculating the distensibility coefficient, defined as the percentage change in LVOT area relative to change in left ventricular pressure. LVOT remodeling was assessed by measuring the posterior LVOT wall thickness. Multivariate linear regression analysis was used to determine independent associations with peak systolic LVOT ellipticity. LVOT area by three-dimensional transesophageal echocardiographic planimetry was compared with areas obtained assuming circular or elliptical geometry.
  
  
  RESULTS
  At end-diastole, LVOT geometry was similar between patients with AS and normal control subjects. In patients with AS, however, the percentage change in cross-sectional area (7.5% vs 14.7%, P < .001) from end-diastole to peak systole was lower compared with normal control subjects, while peak systolic ellipticity index was higher in patients with AS (1.18 vs 1.08, P < .001). Compared with control subjects, patients with AS had lower distensibility coefficients (4.7 ± 1.9 × 10(4) vs 12.5 ± 5.3 × 10(4) mm Hg(-1), P < .001) and higher posterior LVOT wall thickness (3.5 ± 0.8 vs 2.3 ± 0.5 mm, P < .001). In multivariate analysis, posterior LVOT wall thickness and distensibility coefficient were independently associated with peak systolic LVOT ellipticity index. LVOT area underestimation by transthoracic echocardiography was higher in patients with AS when assuming circular geometry (20% vs 12%, P = .001).
  
  
  CONCLUSIONS
  The LVOT is less distensible and undergoes remodeling in severe AS. These changes lead to greater peak systolic ellipticity and greater LVOT cross-sectional area underestimation relative to normal control subjects. These findings have important implications for the assessment of AS severity.
authors: Division of Cardiology, Cardiac Ultrasound Laboratory, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors: Praveen
authors: P
authors: Mehrotra
authors: Division of Cardiology, Cardiac Ultrasound Laboratory, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors: Aidan W
authors: AW
authors: Flynn
authors: Division of Cardiology, Cardiac Ultrasound Laboratory, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors: Katrijn
authors: K
authors: Jansen
authors: Division of Cardiology, Cardiac Ultrasound Laboratory, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors: Timothy C
authors: TC
authors: Tan
authors: Division of Cardiology, Cardiac Ultrasound Laboratory, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors: Gary
authors: G
authors: Mak
authors: Division of Cardiology, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania.
authors: Howard M
authors: HM
authors: Julien
authors: Division of Cardiology, Cardiac Ultrasound Laboratory, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors: Xin
authors: X
authors: Zeng
authors: Division of Cardiology, Cardiac Ultrasound Laboratory, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors: Michael H
authors: MH
authors: Picard
authors: Division of Cardiology, Cardiac Ultrasound Laboratory, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
authors: Jonathan J
authors: JJ
authors: Passeri
authors: Division of Cardiology, Cardiac Ultrasound Laboratory, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts. Electronic address: jhung@partners.org.
authors: Judy
authors: J
authors: Hung
mesh_terms: D000369:Aged, 80 and over; D001024:Aortic Valve Stenosis / Q000150:complications* / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D019560:Echocardiography, Three-Dimensional / Q000379:methods*; D054459:Elasticity Imaging Techniques / Q000379:methods; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D014694:Ventricular Outflow Obstruction / Q000000981:diagnostic imaging* / Q000209:etiology*; D020257:Ventricular Remodeling
keywords: Aortic stenosis; Dynamics; Left ventricular outflow tract; Stiffness; Three-dimensional echocardiography