Gorlin Valve Area
Enter cardiac output, heart rate, systolic ejection period per beat, and mean transvalvular gradient from catheterization to calculate valve area and stenosis severity.
Use thermodilution or Fick cardiac output from cath lab.
For mitral valve, use diastolic filling period; for aortic valve, systolic ejection period per beat.
How to Use This Calculator
Collect cath lab data
Obtain cardiac output, heart rate, mean gradient, and ejection period from invasive hemodynamics.
Choose valve type
Select aortic or mitral to apply appropriate severity thresholds.
Interpret results in context
Combine valve area with echocardiographic gradients, symptoms, and other clinical findings.
Formula
Valve area (cm²) = (CO × 1000) ÷ (HR × SEP × 44.3 × √ΔPmean)
CO = cardiac output (L/min), SEP = systolic (or diastolic) ejection period per beat (s), ΔPmean = mean gradient (mmHg).
Full Description
The Gorlin equation converts invasive flow and pressure measurements into an effective valve area. It accounts for cardiac output, the time the valve is open each beat, and the pressure gradient across the valve. Valve area helps grade stenosis severity and guides timing of intervention, especially when echocardiographic measures are discordant or when invasive assessment is required prior to valve replacement.
Frequently Asked Questions
What is the constant 44.3?
It converts flow in mL/s and pressure in mmHg to area in cm² accounting for blood density and orifice discharge coefficient.
How do arrhythmias affect the calculation?
Average cardiac output and gradients over multiple beats; tachyarrhythmias can shorten ejection period and alter accuracy.
Do I need to adjust for valve prostheses?
The Gorlin equation can be applied to prosthetic valves, but consider manufacturer reference effective orifice areas for comparison.
Can echocardiography replace the Gorlin formula?
Doppler echocardiography is first-line. Use the Gorlin calculation when noninvasive results are inconclusive or pre-procedural confirmation is required.