Gorlin Formula Calculator: Aortic and Mitral Valve Area

Your details

Select the valve you want to assess. The formula constant changes between valves.
Cardiac output in millilitres per minute. To convert from L/min, multiply by 1000. Measured by the Fick method or thermodilution during catheterization.
mL/min
Beats per minute recorded at the time of the catheterization measurement.
bpm
Duration of ventricular ejection per beat in seconds, measured from the aortic pressure tracing. Typical range 0.25 to 0.40 s/beat.
s/beat
Mean transvalvular pressure gradient in mmHg, measured as the time-averaged difference between ventricular and downstream arterial pressure during the flow period. Use mean gradient, not peak-to-peak gradient.
mmHg
Valve areaSevere AS
0.83cm²

Gorlin formula valve area

Hakki approximation0.91cm²
Transvalvular flow rate202mL/s
Square root of gradient5.477√mmHg
Stenosis severitySevere AS
0.83 cm²
Severe stenosis<1Moderate stenosis1-1.5Mild stenosis1.5-2.5Normal2.5+

Calculated aortic valve area is 0.83 cm² (Severe AS).

  • A normal aortic valve area is 3.0 to 4.0 cm². Your calculated area of 0.83 cm² falls in the severe range.
  • The Hakki approximation gives 0.91 cm², differing by 0.08 cm². Large discrepancies (>0.2 cm²) suggest an atypical heart rate or ejection period warranting review.
  • The Gorlin formula measures functional orifice area, not anatomical area. Planimetry by echocardiography and continuity-equation area from Doppler should be used to cross-check the catheterization result.

Next stepSevere aortic stenosis is a class I indication for valve intervention in symptomatic patients. Refer to the ACC/AHA Valvular Heart Disease guidelines for the full decision pathway.

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