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ECHONOMY
Tools for Echocardiographic Calculations
Muhamed Saric, MD, PhD
New York University
 

MS - Continuity Eq

Purpose
To calculate mitral valve area using the continuity principle which states that the stroke volume that passes through the mitral valve in diastole is equal to the stroke volume passing through the LVOT in systole.

Technical Hints
The method is not valid when there is significant mitral or aortic regurgitation.

Calculator

LVOT Diameter (d):

 cm

LVOT VTI
(by pulsed Doppler):

 cm

Mitral valve VTI
(by continuous Doppler):

 cm


 		  

Answers

LVOT Area:

 cm2

Mitral Valve Area (MVA):

 cm2

Formulas

LVOT Area = (1/2 * d)2 * pi

MVA = LVOT Area * (LVOT VTI / MV VTI)

Reference
Holen J, Aaslid R, Landmark K, Simonsen S, Ostrem T. Determination of effective orifice area in mitral stenosis from non-invasive ultrasound Doppler data and mitral flow rate. Acta Med Scand 1977;201:83-88.

Karp K, Teien D, Eriksson P. Doppler echocardiographic assessment of the valve area in patients with atrioventricular valve stenosis by application of the continuity equation. J Intern Med 1989;225:261 266.