Calculate cardiac valve area using the Gorlin formula from catheterization data including cardiac output, heart rate, and pressure gradient.
The Gorlin formula is a foundational equation in interventional cardiology used to calculate cardiac valve area from hemodynamic data obtained during cardiac catheterization. Developed by Richard Gorlin and S. Gordon Gorlin in 1951, this formula remains a gold-standard method for assessing the severity of valvular stenosis when non-invasive imaging is inconclusive or discordant.
The formula accounts for cardiac output, heart rate, the systolic ejection period (for aortic valve) or diastolic filling period (for mitral valve), and the mean transvalvular pressure gradient. By integrating these parameters, the Gorlin equation provides a quantitative valve area that directly correlates with stenosis severity according to ACC/AHA guidelines.
This calculator supports both aortic and mitral valve assessments, automatically applies the appropriate Gorlin constant (44.3 for aortic, 37.7 for mitral), and grades stenosis severity based on current guideline criteria. The tool also provides indexed valve area, estimated peak velocity, and doppler continuity estimates for cross-validation with echocardiographic data.
The Gorlin formula calculator provides rapid, accurate valve area calculations from catheterization hemodynamic data, essential for surgical decision-making in valvular heart disease. It eliminates manual calculation errors and provides instant severity grading with visual concordance checks. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation.
Gorlin Formula: Valve Area = (CO × 1000) / (HR × Period × C × √ΔP), where CO = cardiac output (L/min), HR = heart rate (bpm), Period = systolic ejection period or diastolic filling period (sec), C = Gorlin constant (44.3 aortic, 37.7 mitral), ΔP = mean pressure gradient (mmHg).
Result: 0.91 cm²
With CO of 5.0 L/min, HR of 75 bpm, SEP of 0.33 sec, and a mean gradient of 30 mmHg, the Gorlin formula yields a valve area of 0.91 cm², classified as moderate aortic stenosis.
The Gorlin formula was published in 1951 in the American Heart Journal and quickly became the standard method for calculating valve area during cardiac catheterization. Before the era of echocardiography, catheterization with Gorlin formula calculation was the only quantitative method to assess valvular stenosis severity. Even today, when echocardiographic and cath data are discordant, the Gorlin formula provides the definitive invasive measurement.
The primary limitation of the Gorlin formula is its flow-dependence: in low cardiac output states, the formula underestimates true valve area because flow across the valve is reduced. The Hakki simplification (AVA = CO / √ΔP) eliminates the need for ejection period measurement and performs reasonably well at heart rates between 60–100 bpm. The simplified Gorlin formula and planimetry by echocardiography or CT are modern alternatives.
Contemporary practice uses multimodality imaging to assess valvular disease. Echocardiographic continuity equation, planimetry by 3D TEE, and CT calcium scoring all complement catheterization data. The Gorlin formula remains the invasive gold standard and is particularly valuable in discordant cases, low-flow low-gradient stenosis evaluation, and pre-procedural assessment for transcatheter valve interventions.
The Gorlin formula calculates cardiac valve area from catheterization data, helping grade the severity of valvular stenosis when echocardiographic results are unclear or discordant. Use this as a practical reminder before finalizing the result.
The empiric constant is 44.3 for the aortic valve and 37.7 for the mitral valve. These constants were derived from hydraulic orifice flow equations and have been validated in clinical studies.
The formula is reliable in high-flow states but can underestimate valve area in low cardiac output conditions. The simplified Gorlin formula and Hakki method may be alternatives in low-flow states.
ACC/AHA guidelines define severe aortic stenosis as valve area < 0.6 cm² (or < 1.0 cm² with symptoms), mean gradient > 40 mmHg, and peak velocity > 4.0 m/s.
Yes, using the diastolic filling period instead of systolic ejection period and the mitral Gorlin constant of 37.7. Mitral valve area < 1.0 cm² indicates severe mitral stenosis.
Indexed valve area divides the calculated valve area by body surface area (BSA), which is important in small patients where a nominally normal valve area may still be functionally stenotic. Keep this note short and outcome-focused for reuse.