Gorlin Formula Calculator

The Gorlin formula is derived from hydraulic principles of fluid flow through an orifice. It relates the flow across a valve during its open period to the square root of the mean pressure gradient across that valve. For the aortic valve, the formula calculates AVA using systolic ejection period (SEP) and mean aortic gradient: AVA = Cardiac Output / (Heart Rate × Systolic Ejection × 44.3 × √(Aortic Gradient)). For the mitral valve, it computes MVA using diastolic filling period (DFP) and mean mitral gradient:

Let us walk through a practical example for calculating the mitral valve area (MVA). Suppose a patient has a cardiac output of 5.0 L/min, a heart rate of 75 beats/min, a diastolic filling period of 0.4 seconds per beat, and a mean mitral pressure gradient of 9 mmHg. First, take the square root of the gradient: √9 = 3. Next, multiply the heart rate, diastolic filling time, constant 37.7, and the square root of the gradient: 75 × 0.4 × 37.7 × 3 = 3,393. Finally, divide the cardiac output (converted to mL/min as 5000) by this product: 5000 / 3393 equals approximately 1.47 cm². This result indicates moderate mitral stenosis.

Ensure that all input parameters, particularly pressure gradients and flow rates, are obtained via careful cardiac catheterization or high-fidelity echocardiography to prevent compounding errors. Always double-check unit conversions for cardiac output (typically liters per minute) and time intervals (seconds per beat). Remember that the Gorlin formula can become less reliable in the presence of significant valvular regurgitation, so clinical correlation is always required.