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


Purpose

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 (19261991; 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. 
Calculator

Cardiac output (CO) 

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

seconds 
Mean pressure gradient (MPG): 

mm Hg 
Heart rate (HR): 

beats per minute 


Answers

Aortic valve area 

cm^{2} 
Mitral valve area 

cm^{2} 
Formula
Valve area = k * [CO / (44.3 * HR * FP * sq root of MPG)]
k = 1 for aortic valve k = 0.85 for mitral valve 
References

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):129. Reevaluated in
J Am Coll Cardiol. 1990 Jan;15(1):2467.
