Gorlin formula
1. The Gorlin formula is primarily used to calculate:
The Gorlin formula calculates effective valve area (e.g., aortic or mitral stenosis) using flow and pressure gradients.
2. In the Gorlin formula, valve area is inversely proportional to:
A higher mean pressure gradient reduces calculated valve area for a given flow.
3. The Gorlin formula for aortic valve area includes which constant?
The constant 44.3 is used to convert flow and gradient units to cmยฒ for aortic valve area.
4. The Gorlin formula requires measurement of:
Both cardiac output (flow) and mean pressure gradient are essential in Gorlinโs formula.
5. A valve area < 1.0 cmยฒ by Gorlin formula usually indicates:
Valve area below 1.0 cmยฒ is considered severe for both aortic and mitral stenosis.
6. Which invasive tool is required to apply the Gorlin formula?
The Gorlin formula is applied during invasive hemodynamic assessment at cath lab.
7. In mitral stenosis, the Gorlin formula includes the correction factor:
For mitral valve area, the constant 37.7 is used.
8. The Gorlin formula assumes steady flow, but in AF the limitation is:
In atrial fibrillation, varying cycle lengths make valve area calculation less reliable.
9. Which clinical lesion was first quantified using Gorlinโs formula?
Gorlin and Gorlin first developed the formula for mitral stenosis in the 1950s.
10. Which of the following can falsely elevate calculated valve area?
Increased flow can make a stenotic valve appear less severe (larger area).
11. Gorlin formula uses mean gradient measured by:
Pressure is measured across stenotic valve invasively during cath.
12. A Gorlin-calculated aortic valve area of 0.7 cmยฒ indicates:
Severe aortic stenosis is defined as AVA < 1.0 cmยฒ.
13. In low-flow, low-gradient AS, Gorlin formula may:
Low flow may lead to falsely large valve area estimation.
14. The formula requires which physiologic measurement for CO?
Cardiac output is needed to calculate flow across the valve.
15. Gorlin formula in mitral stenosis is most accurate when:
Stable rhythm and output ensure reliable results.
16. The Gorlin constant accounts for:
The constant ensures the formula yields cmยฒ values from mmHg and flow units.
17. What is the main role of Gorlin formula today?
Used in cath lab when echo results are uncertain.
18. In severe calcific AS with low output, Gorlin formula may suggest:
Dobutamine stress is often used to differentiate true vs pseudosevere AS.
19. Which factor is NOT part of Gorlin calculation?
LV wall thickness is not a variable in Gorlinโs equation.
20. The original Gorlin equation was described in:
Gorlin & Gorlin first published their formula in 1951.
Gorlin Formula โ Explanation & Calculator
What is the Gorlin formula?
The Gorlin formula is an invasive hemodynamic equation used to estimate the effective valve orifice area from cardiac catheterization measurements (commonly for aortic and mitral stenosis). It uses cardiac output, the filling/ejection time per beat, heart rate, and the mean transvalvular pressure gradient.
General form
Valve area = CO / (HR ร TP ร K ร โ(ฮPmean))
where:
• CO = Cardiac output (L/min) โ the calculator converts to ml/min internally.
• HR = Heart rate (beats/min).
• TP = Time period per beat (s/beat): Systolic Ejection Period (SEP) for aortic, or Diastolic Filling Period (DFP) for mitral.
• ฮPmean = Mean transvalvular pressure gradient (mmHg).
• K = empirical constant (aortic โ 44.3, mitral โ 37.7).
• CO = Cardiac output (L/min) โ the calculator converts to ml/min internally.
• HR = Heart rate (beats/min).
• TP = Time period per beat (s/beat): Systolic Ejection Period (SEP) for aortic, or Diastolic Filling Period (DFP) for mitral.
• ฮPmean = Mean transvalvular pressure gradient (mmHg).
• K = empirical constant (aortic โ 44.3, mitral โ 37.7).
Common specific forms
- Aortic valve area (AVA):AVA (cmยฒ) = CO / (HR ร SEP ร 44.3 ร โ(ฮPmean))
- Mitral valve area (MVA):MVA (cmยฒ) = CO / (HR ร DFP ร 37.7 ร โ(ฮPmean))
Notes & limitations
- CO measurement method (Fick vs thermodilution) affects precision.
- Accuracy reduced in low-output states, atrial fibrillation, significant regurgitation, or poor pressure tracing quality.
- Doppler echocardiography is commonly used noninvasively, but Gorlin remains a catheterization reference.
Educational use only. Results are approximate and depend on accurate inputs. Clinical decisions should be based on full invasive report and expert interpretation.
Gorlin Calculator
Enter CO in L/min (e.g., 4.5 L/min). The tool converts to ml/min.
For AVA (aortic): enter SEP (systolic ejection period). Typical SEP โ 0.30โ0.40 s. For MVA (mitral): enter DFP (diastolic filling period), typical โ 0.45โ0.60 s.
โ
Gorlin Formula โ Explanation & Calculator
What is the Gorlin formula?
The Gorlin formula estimates valve area from invasive hemodynamic measurements, widely applied for aortic and mitral stenosis.
General form:
Valve Area = CO / (HR ร TP ร K ร โฮPmean)
Valve Area = CO / (HR ร TP ร K ร โฮPmean)
Constants
- Aortic valve: K = 44.3, TP = SEP (systolic ejection period)
- Mitral valve: K = 37.7, TP = DFP (diastolic filling period)
Clinical Use
- Severe AS: AVA < 0.8 cmยฒ
- Severe MS: MVA โค 1.0 cmยฒ
- Requires careful invasive measurement
Note: Educational calculator โ not for standalone clinical decision-making.
Gorlin Calculator
SEP for AVA, DFP for MVA
Presets:
โ
