Gorlin Formula Calculator

What Is the Gorlin Formula?

The Gorlin formula estimates valve area from cardiac catheterization hemodynamics. It relates cardiac output, heart rate, flow period, and the mean transvalvular pressure gradient to effective orifice area. This calculator computes both aortic valve area (AVA) and mitral valve area (MVA) from shared cardiac output and heart rate inputs. For echocardiographic AVA, see the Aortic Valve Area Calculator.

Formulas Used

Aortic valve area in cm² is calculated as cardiac output in mL/min divided by the product of 44.3, heart rate, systolic ejection period in seconds, and the square root of the aortic mean gradient in mmHg. Mitral valve area uses the same cardiac output with constant 37.7, diastolic filling period, and the square root of the mitral mean gradient.

$$AVA = \frac{CO\ (\text{mL/min})}{44.3 \times HR \times SEP \times \sqrt{\Delta P_{aortic}}}$$

$$MVA = \frac{CO\ (\text{mL/min})}{37.7 \times HR \times DFP \times \sqrt{\Delta P_{mitral}}}$$

Stenosis Severity Grading

For the aortic valve, severe stenosis is AVA at or below 1 cm², moderate is 1 to 1.5 cm², mild is 1.5 to 3 cm², and normal is about 3 to 4 cm². For the mitral valve, severe stenosis is MVA below 1 cm², moderate is 1 to 1.5 cm², mild is 1.5 to 4 cm², and normal is about 4 to 6 cm². These cutoffs guide clinical decisions but should always be interpreted with symptoms and imaging.