Estimation of the mitral valve area using the principle of conservation of mass by analyzing the Proximal Isovelocity hemispheric Surface Area (PISA) of the flow convergence on the atrial side. Due to funnel shape of the proximal convergence, it is important to take into account the angle correction, α when the aliasing velocity (Vr <40 cm/s). If the aliasing velocity is high (Vr >40 cm/s), it is not as important since the PISA approximates a hemisphere.
MVA =
2πr2
*
Vr
VMax
*
α0
1800
Variable
Definition
Input
2 × π × r2
Proximal isovelocity hemispheric surface area at a radial distance r from the orifice
Vr
Aliasing velocity at the radial distance r (cm/s)
VMax
Peak mitral stenosis velocity by CW (m/s)
α
Angle between two mitral leaflets on the atrial side (degree0)
Output
VFR
Volume Flow Rate (cc)
MVA
Mitral valve area (cm2)
References
Baumgartner H, et al. Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice. J Am Soc Echocardiogr. 2009 Jan;22(1):14, 17.
Rodriguez L., et al. Validation of the proximal flow convergence method. calculation of orifice area in patients with mitral stenosis. Circulation. 1993 Sep; 88(3):1157-65.
Developer: Edward Brawer