title: Impact of energy loss index and valvuloarterial impedance in patients with aortic stenosis using three-dimensional echocardiography.
abstract: BACKGROUND
  Energy loss index (ELI) and valvuloarterial impedance (Z(va)) have been evaluated with a lack of three-dimensional (3D) information regarding the left ventricular outflow tract (LVOT) and sino-tubular junction (STJ). Our aim of this study is to compare the difference of ELI and Z(va) between two-dimensional (2D) and 3D echocardiography.
  
  
  METHODS
  In 74 patients with moderate-to-severe aortic stenosis, the effective orifice area index (EOAI: EOA/body surface area) was calculated by continuity equation based on both 2D transthoracic echocardiography (2DTTE) and 3D transesophageal echocardiography (3DTEE). The areas of the LVOT and the STJ were calculated with the assumption of π × (dimension/2)(2) by 2DTTE and were measured directly by 3DTEE. Severe AS was defined as EOAI or ELI <0.6 cm(2) /m(2) or Z(va) ≥ 4.5 mmHg/mL per m(2) .
  
  
  RESULTS
  Both the LVOT and STJ were elliptical, and LVOT was more elliptical than STJ. The ELI by 3DTEE (0.58 cm(2) /m(2) [median]) was larger than the other 3 values: EOAI on 2DTTE = 0.41, P < 0.01; EOAI on 3DTEE = 0.49, P < 0.01; and ELI on 2DTTE = 0.49, P < 0.01. Furthermore, Z(va) by 2DTTE, 4.7 mmHg/mL per m(2), was larger than that by 3DTEE (3.8, P < 0.01).
  
  
  CONCLUSIONS
  2DTTE underestimated EOAI and ELI relative to 3DTEE and overestimated Z(va) relative to 3DTEE.
authors.affiliation: Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California.
authors.forename: Takeji
authors.initials: T
authors.lastname: Saitoh
authors.forename: Jun
authors.initials: J
authors.lastname: Tanaka
authors.forename: Azusa
authors.initials: A
authors.lastname: Furugen
authors.forename: Kenji
authors.initials: K
authors.lastname: Harada
authors.forename: Masaki
authors.initials: M
authors.lastname: Izumo
authors.forename: Yoko
authors.initials: Y
authors.lastname: Fukuoka
authors.forename: Takahiro
authors.initials: T
authors.lastname: Shiota
mesh_terms: D000369:Aged, 80 and over; D001011:Aorta / Q000000981:diagnostic imaging*; D001021:Aortic Valve / Q000000981:diagnostic imaging*; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging*; D019560:Echocardiography, Three-Dimensional / Q000379:methods*; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D009929:Organ Size; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
keywords: aortic valve stenosis; diagnosis; three-dimensional echocardiography