Home
Up

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

Hakki Eq.

Purpose
To calculate the aortic valve area (AVA) using a simplified Gorlin equation. Original Gorlin formula calculates AVA from 5 parameters: cardiac output, mean pressure gradient, heart rate, systolic ejection period and the constant 44.3.

Hakki and colleagues realized that 44.3 * SEP * HR is approximately 1000. If the cardiac output is expressed in liters/minute (rather than in mL/min as in Gorlin eq.), AVA can be calculated using only the cardiac output (CO) and the square root of mean pressure gradient (MPG).

Technical Hints
Make sure the cardiac output is expressed in liters per minute!

Calculator

Cardiac output  (CO)

 liters/minute

Mean pressure gradient (MPG):

 mm Hg


 		  

Answers
Aortic valve area  cm2


Formula

Valve area = CO / sq root of MPG

References

Hakki A, Iskandrian A, Bemis C, Kimbiris D, Mintz G, Segal B, Brice C. A simplified valve formula for the calculation of stenotic cardiac valve areas. Circulation 1981;63(5):1050–5.