title: Three-dimensional surface area of the aortic valve orifice by three-dimensional echocardiography: clinical validation of a novel index for assessment of aortic stenosis.
abstract: BACKGROUND
  A direct and accurate method of assessing aortic valve area (AVA) in patients with aortic stenosis (AS) is desirable because of the well-known theoretical and practical limitations of the currently available methods. We assessed the clinical feasibility and accuracy of a novel index, the 3-dimensional surface area (3-DSA) of the aortic valve orifice by 3-dimensional transesophageal echocardiography (3-DTEE) in patients with AS.
  
  
  METHODS
  Intraoperative 3-DTEE was performed in 23 consecutive patients (mean age 58 +/- 15 years) with valvular AS using a Toshiba SSA-380A system with a multiplane TEE probe and a TomTec EchoScan system. The 3-DTEE acquisition, processing and reconstruction were conducted and the aortic valve orifice presented using a "surgeon's aortotomy view" (aortic valve orifice as if viewed through an open aortic root). The 3-D images were videotaped and calibrated and the 3-DSA measured by planimetry of the inner surface of the aortic valve leaflets at the maximal systolic opening using the dynamic 3-D images. For comparison, the 2-D cross sectional area (2-DCSA) of the aortic valve was also determined by 2-DTEE. The 3-DSA and 2-DCSA were compared with the AVA by the invasive Gorlin formula and the Doppler continuity equation method by transthoracic echocardiography.
  
  
  RESULTS
  The 3-DSA and 2-DCSA measurements were feasible in all but one patient. Both 3-DSA and 2-DCSA correlated moderately well with the AVA by the Gorlin formula (n = 17, r = 0.66, standard error of the estimate [SEE] = 0.3 cm2, P <.05 for 3-DSA and r = 0.61, SEE = 0. 5 cm2 P <.05 for 2-DCSA, respectively). They also correlated well with the AVA by Doppler continuity equation method (n = 22, r = 0.90, SEE = 0.1 cm2, P <.05 for 3-DSA and r = 0.83, SEE = 0.3 cm2, P <.05 for 2-DCSA, respectively). There was no statistically significant difference between the 3-DSA and AVA by both the Gorlin formula (Delta = 0.1 +/- 0.3 cm2, P =.3) and the Doppler continuity equation (Delta = -0.0 +/- 0.3 cm2, P =.7). In contrast, the 2-DCSA significantly overestimated AVA by the Gorlin formula (Delta = 0.5 +/- 0.5 cm2, P <.005) and by the Doppler continuity equation (Delta = 0.5 +/- 0.6 cm2, P <.0001).
  
  
  CONCLUSIONS
  Planimetry of 3-DSA of the aortic valve orifice by 3-DTEE is a clinically feasible and relatively accurate technique for assessment of AVA and is superior to 2-DCSA by 2-DTEE.
authors.affiliation: Section of Cardiology, Department of Cardiothoracic Surgery, and Department of Anesthesiology, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
authors.forename: S
authors.initials: S
authors.lastname: Ge
authors.forename: J G
authors.initials: JG
authors.lastname: Warner
authors.forename: T P
authors.initials: TP
authors.lastname: Abraham
authors.forename: N D
authors.initials: ND
authors.lastname: Kon
authors.forename: R F
authors.initials: RF
authors.lastname: Brooker
authors.forename: A M
authors.initials: AM
authors.lastname: Nomeir
authors.forename: K M
authors.initials: KM
authors.lastname: Fowle
authors.forename: P
authors.initials: P
authors.lastname: Burgess
authors.forename: D W
authors.initials: DW
authors.lastname: Kitzman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D019560:Echocardiography, Three-Dimensional; D017548:Echocardiography, Transesophageal / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results