# Gorlin Formula Calculator

Created by Michael Darcy
Reviewed by Łucja Zaborowska, MD, PhD candidate and Adena Benn
Based on research by
Gorlin R, Gorlin SG Hydraulic formula for calculation of the area of the stenotic mitral valve, other cardiac valves, and central circulatory shunts American Heart Journal (January 1951)See 3 more sources
Gorlin R, Gorlin SG A generalized formulation of the Gorlin formula for calculating the area of the stenotic mitral valve and other stenotic cardiac valves Journal of the American College of Cardiology (January 1990)Dean LS, Kern MJ Measuring Valve Gradients and Areas Journal of the Society for Cardiovascular Angiography & Interventions (August 2022)Otto CM, Nishimura RA, Bonow RO, et al. 2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines Circulation (February 2021)
Last updated: Nov 25, 2022

The Gorlin formula calculator is a tool that can assist you in calculating the aortic valve area indirectly. You'll also see how to compare the results with the aortic stenosis grading.
Additionally, you'll find the Gorlin equation for the mitral valve area and the guidelines for the mitral stenosis grading.

We try our best to make our Omni Calculators as precise and reliable as possible. However, this Gorlin formula calculator can never replace a professional medical assessment.

Before administering any drugs, fluids, or treatment to your patient, make sure you know the correct dose and method.

## Applications of the Gorlin formula calculator

The Gorlin formula allows you to estimate the areas of human cardiac valves indirectly. Most commonly, it is used to calculate either the mitral valve area (MVA) or the aortic valve area (AVA).
These small body parts have an important role - they help regulate blood flow. It's essential that they function correctly; however, this isn't always the case. Reduced valve area may indicate stenosis - a condition where the valve opening is narrowed, thus obstructing blood circulation.
There are several methods to calculate mitral or aortic valve area; our Gorlin formula calculator can help you apply one of them.

Aortic stenosis (AS) is among the most common valvular diseases. Due to its location, it may result in reduced blood flow to the aorta and, thus, the rest of your body. Moreover, the left ventricle has to contract harder to try and push the blood through the valve. The symptoms often include:

• Chest pain;
• Shortness of breath;
• Rapidly fluttering heartbeat; and
• Fatigue.

It usually develops later in life, mainly due to , scarring, or rheumatic fever. However, younger people can suffer from it, too - for example, if they're born with a .
Unsurprisingly, the valve area isn't the only clinical parameter affected in aortic stenosis. Below, you can see the aortic stenosis grading as per the .

Classification

AVA (cm2)

ΔP (mmHg)

Vmax (m/s)

Normal

3 - 4

< 10

< 2.0

Mild

1.5 - 3

10 - 19

2.0 - 2.9

Moderate

1 - 1.5

20 - 39

3.0 - 3.9

Severe

≤ 1

⩾ 40

⩾ 4.0

In the above table:

• $\Delta P$ - Mean pressure gradient; and
• $V_{\text{max}}$ - Maximum aortic velocity.

Note that the full guidelines include more detailed cases depending on the valve anatomy or the presence of symptoms.

## Calculating aortic valve area

The underlying equation of the Gorlin formula calculator for calculating the aortic valve area is given by:

$\small \text{AVA} = \frac{\text{CO}}{44.3 \times \text{HR} \times \text{SEP} \times \sqrt{\Delta P}}$

where:

• $\text{CO}$ - Cardiac output in ml/min;
• $\text{HR}$ - Heart rate; and
• $\text{SEP}$ - Systolic ejection period in sec/beat.

$\Delta P$ is expressed in mmHg, whereas the resultant aortic valve area is in cm2.

⚠️ In low-flow states (cardiac output below 2.5 l/min), , implying more severe stenosis. In such cases, the aortic valve area calculator, based on the continuity equation, may be a better option.

There are several methods of measuring the above hemodynamic parameters; for example: ECG (heart rate), echocardiogram, CT scan, or cardiac catheterization.

Mitral stenosis (MS) restricts blood flow from the left atrium to the left ventricle. The resulting pressure buildup in the heart may also lead to lung fluid congestion. The symptoms are usually similar to aortic stenosis, but there are some differences - for example, the heart sounds are different.

💡 Aortic and mitral stenoses can be concurrent. AS can also be seen in the presence of another mitral valve disease - mitral regurgitation.

We have shown the mitral stenosis grading with typical reference values in the table below.

Classification

MVA (cm2)

ΔP (mmHg)

PASP (mmHg)

Normal

4 - 5

-

10 - 20

Mild

1.5 - 4

< 5

20 - 30

Moderate

1 - 1.5

5 - 10

30 - 50

Severe

< 1

> 10

> 50

$\text{PASP}$ is the pulmonary arterial systolic pressure.

## Gorlin equation for mitral valve area

The Gorlin equation for mitral valve area is given by:

$\small\text{MVA} = \frac{\text{CO}}{37.7 \times \text{HR} \times \text{DFP} \times \sqrt{\Delta P}}$

where $\text{DFP}$ is the diastolic filling period in sec/beat.

Notice that it's very similar to the formula for calculating the aortic valve area. In fact, it was empirically found that for known AVA we can (approximately) calculate the mitral valve area using:

$\small\text{MVA} \approx \frac{\text{AVA}}{0.85}.$

If you're working with Doppler echocardiography, our PISA calculator can also help you determine MVA.

## Example: calculating aortic valve area

Let us finish with an example of how the Gorlin formula calculator works in practice. Assume that during a cardiac examination, you established the hemodynamic parameters to have the following values:

• Heart rate: 75 bpm;
• Cardiac output: 5.5 l/min = 5500 ml/min;
• Mean pressure gradient: 15 mmHg; and
• Systolic ejection period: 0.25 sec/beat.

With the goal of calculating the aortic valve area, let us substitute these values into the Gorlin formula:

\begin{aligned} \small\text{AVA} &= \frac{5500 \frac{\text{ml}}{\text{min}}}{44.3 \times 75 \ \frac{\text{beat}}{\text{min}} \times 0.25 \ \frac{\text{sec}}{\text{beat}}\times \sqrt{15 \ \text{mmHg}}} \\ &\approx 1.7 \ \text{cm}^2. \end{aligned}

The Gorlin formula calculator displays the information that this may indicate mild aortic stenosis, which agrees with the grading table above.

## FAQ

### How do I calculate the mitral valve area?

To calculate the mitral valve area (MVA):

1. Determine the patient's diastolic filling period (DFP) in sec/beat, cardiac output in ml/min, and heart rate (HR).
2. Determine the flow:

flow = cardiac output / (DFP × HR).

1. Find the mean valvular pressure gradient.
2. Substitute into the Gorlin equation for mitral valve area:

MVA = flow / (37.7 × √mean pressure gradient).

### How do I calculate the aortic valve area?

To calculate the aortic valve area (AVA):

1. Establish the systolic ejection period (SEP) in sec/beat, cardiac output in ml/min, and heart rate (HR).
2. Find the flow:

flow = cardiac output / (SEP × HR).

1. Determine the mean valvular pressure gradient.
2. Finish calculating the aortic valve area by substituting into the Gorlin formula:

AVA = flow / (44.3 × √mean pressure gradient).

### What is the normal mitral valve area?

The normal mitral valve area (MVA) is in the range of 4 to 5 cm². If MVA is below 4 cm², it may be a sign of mitral stenosis. The area below 1.5 cm² typically characterizes more severe stages of this disease.

### What is the normal aortic valve area?

The normal aortic valve area (AVA) is between 3 and 4 cm². AVA below 3 cm² may indicate aortic stenosis. In particular, values below 1 cm² are typically associated with a severe stage of this disease.

Michael Darcy
Cardiac output
liters
/min
Heart rate
bpm
Aortic valve
mmHg
Systolic ejection period
sec
/beat
Aortic valve area (AVA)
cm²
Mitral valve
mmHg
Diastolic filling period
sec
/beat
Mitral valve area (MVA)
cm²
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