title: Application of color Doppler flow mapping to calculate effective regurgitant orifice area. An in vitro study and initial clinical observations.
abstract: BACKGROUND
  Analogous to stenotic valve area in the assessment of valvular stenosis, regurgitant orifice area (ROA) represents a fundamental parameter to assess valvular insufficiency. However, this parameter has not been routinely available up to now. In this study, we introduce the concept and provide the methodology to calculate regurgitant orifice area noninvasively, based on the analysis of the proximal flow convergence zone.
  
  
  RESULTS
  In an in vitro study, we showed the feasibility and the accuracy of calculating effective ROA by the proximal flow convergence method throughout a range of driving pressures. The calculated and true ROA showed an excellent correlation with r = .992, delta ROA = -1.4 +/- 2.9 mm2. We then applied this concept clinically in 77 patients with mitral regurgitation and showed a very good correlation between effective ROA calculated by the proximal flow convergence method and calculated by the Doppler echocardiographic method: r = .95, delta ROA = -0.2 +/- 3.9 mm2. The ROA also correlated very well with Doppler echocardiographic-derived regurgitant stroke volume (r = .93) and regurgitant fraction (r = .82). In a subgroup of 20 patients who underwent invasive evaluation, the calculated effective ROA also correlated well with the angiographic grade of mitral regurgitation (rho = .81).
  
  
  CONCLUSIONS
  We conclude that effective ROA represents unique information on the severity of a regurgitant lesion and can easily be calculated by the proximal flow convergence method. This new parameter should enhance our understanding and improve the serial assessment of valvular regurgitation.
authors.affiliation: Department of Cardiology, Cleveland Clinic Foundation, OH 44195.
authors.forename: P M
authors.initials: PM
authors.lastname: Vandervoort
authors.forename: J M
authors.initials: JM
authors.lastname: Rivera
authors.forename: D
authors.initials: D
authors.lastname: Mele
authors.forename: I F
authors.initials: IF
authors.lastname: Palacios
authors.forename: R E
authors.initials: RE
authors.lastname: Dinsmore
authors.forename: A E
authors.initials: AE
authors.lastname: Weyman
authors.forename: R A
authors.initials: RA
authors.lastname: Levine
authors.forename: J D
authors.initials: JD
authors.lastname: Thomas
mesh_terms: D001783:Blood Flow Velocity / Q000502:physiology; D015150:Echocardiography, Doppler / Q000379:methods*; D005240:Feasibility Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008943:Mitral Valve / Q000000981:diagnostic imaging; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000503:physiopathology; D008955:Models, Cardiovascular; D008961:Models, Structural; D012044:Regression Analysis