Tools for Echocardiographic Calculations

Muhamed Saric, MD, PhD
New York University

Gorlin Eq.


To calculate the mitral or aortic valve based on a formula that combines the fundamental equation of fluid mechanics (flow = velocity * area), and the Bernoulli equation (which expresses velocity in terms of pressure). The formula was devised by a father and son team: S.G. Gorlin (father, an engineer), and Dr. Richard Gorlin (1926-1991; son, a cardiologist).

Technical Hints

The original Gorlin formula is used for the aortic valve area. Based on an empiric constant, the mitral valve area is 85% of the valve area calculated by the original Gorlin formula.


Cardiac output  (CO)


Flow period (FP)
SEP (systolic ejection period for aortic valve)
DFP (diastolic flow perior for mitral valve)


Mean pressure gradient (MPG):

 mm Hg

Heart rate (HR):

 beats per minute



Aortic valve area  cm2

Mitral valve area



Valve area = k * [CO / (44.3 * HR * FP * sq root of MPG)]

k = 1 for aortic valve

k = 0.85 for mitral valve


Gorlin R, Gorlin SG. Hydraulic formula for calculation of the area of the stenotic mitral valve, other cardiac valves, and central circulatory shunts. I. Am Heart J. 1951 Jan;41(1):1-29. Reevaluated in J Am Coll Cardiol. 1990 Jan;15(1):246-7.