# Mitral Valve Area Calculator

Created by Michael Darcy
Reviewed by Łucja Zaborowska, MD, PhD candidate and Adena Benn
Based on research by
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)See 4 more sources
Voelker W, Regele B, et al. Value of a modified continuity equation method to quantify mitral valve area in patients with mitral stenosis and sinus rhythm Klinische Wochenschrift (December 1991)Nakatani S, Masuyama T Value and limitations of Doppler echocardiography in the quantification of stenotic mitral valve area: Comparison of the pressure half-time and the continuity equation methods Circulation (January 1977)Cherry AD, Maxwell CD, et al. Intraoperative Evaluation of Mitral Stenosis by Transesophageal Echocardiography Anesthesia and analgesia (July 2016)Unger P, Clavel MA, et al. Pathophysiology and management of multivalvular disease Nature Reviews Cardiology (July 2016)
Last updated: Mar 24, 2023

The mitral valve area calculator can help you calculate mitral valve area using three indirect methods: pressure-half time, deceleration time, and the mitral valve area continuity equation.

This quantity helps diagnose certain valvular diseases. If you'd like to learn more, read on to find the mitral stenosis criteria and the normal mitral valve area values.

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

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

## Mitral valve area in mitral stenosis and other diseases

The mitral valve is responsible for regulating the blood flow from the left atrium to the left ventricle. It opens only in one direction, so no fluid should be able to return to the atrium during systole when the valve closes. As you can imagine, there's plenty of room for something to go wrong, which is when we deal with diseases. In particular:

• If the valve becomes too floppy, we're considering an MVP. In this case, this stands for rather than Most Valuable Player. Floppiness may prevent the valve from closing tightly, sometimes allowing backflow into the left atrium.

• In fact, there is a separate name for a valve not closing properly and leaking. This condition is described further in the EROA mitral regurgitation calculator.

• When the valve doesn't open as widely as it should, it's mitral stenosis. This is the case where the mitral valve area calculator can be helpful, as the valvular area may indicate mitral stenosis severity. We explore this disease below.

## Mitral stenosis criteria

The mitral valve area in mitral stenosis (MS) is reduced, obstructing blood flow. Consequentially, there may be a pressure build-up leading to lung fluid congestion. Some of the symptoms of MS are:

• Breathlessness;
• Tiredness;
• Heart palpitations;
• Chest pain; and
• Dizziness.

It usually develops later in life, primarily due to rheumatic fever, a build-up of calcium deposits, or radiation therapy. However, it is also possible to be born with a that will cause problems over time.

🔎 Mitral and aortic stenoses can be concurrent. Similarly, the latter is also related to the valvular area as described in the aortic valve area calculator.

While the valvular area often indicates mitral stenosis severity, this isn't the only consideration in the diagnostic process. We have shown the mitral stenosis criteria as well as the normal mitral valve area below.

Classification

MVA (cm2)

PHT (ms)

ΔP (mmHg)

PASP (mmHg)

Normal

4-5

< 60

-

10-20

Mild

1.5-4

< 150

< 5

20-30

Moderate

1-1.5

150-220

5-10

30-50

Severe

< 1

≥ 220

> 10

> 50

In the above table:

• $\text{MVA}$ – Mitral valve area;
• $\text{PHT}$ – Pressure half-time; and
• $\text{PASP}$ – Pulmonary arterial systolic pressure.

## Mitral valve area – continuity equation with derivation

While it is possible to determine the MVA directly, there are also several indirect methods. They are primarily based on the readings from the heart imaging – you can read more about it in the Doppler echo cardiac output calculator.

We'll look at the mitral valve area continuity equation first. The underlying principle is that the stroke volume flowing into a chamber must equal the volume flowing out. Approximating the left ventricular outflow tract (LVOT) cross-section to be a circle (you can imagine it as a pipe), we can write

$\small r_{\text{LVOT}} = \frac{d_{\text{LVOT}}}{2}$
$\small A_{\text{LVOT}} = \pi r_{\text{LVOT}}^2$

where:

• $r_{\text{LVOT}}$ – LVOT radius;
• $d_{\text{LVOT}}$ – LVOT diameter; and
• $A_{\text{LVOT}}$ – LVOT cross-sectional area.

Knowing that stroke volume is equal to the product of cross-sectional area and the velocity time integrals, we get

\small \begin{aligned} \mathrm{SV_{LVOT}} &= \mathrm{SV_{MV}} \\ A_{\text{LVOT}} \cdot \mathrm{VTI_{LVOT}} &= \text{MVA} \cdot \mathrm{VTI_{MV}} \end{aligned}

where:

• $\mathrm{SV_{LVOT}}$ – Stroke volume through left ventricular outflow tract;
• $\mathrm{SV_{LVOT}}$ – Stroke volume across mitral valve;
• $\mathrm{VTI_{LVOT}}$ – LVOT ; and
• $\mathrm{VTI_{MV}}$ – Velocity time integral of mitral valve.

Velocity time integral is also referred to as stroke distance.

Simple rearrangement gives us the mitral valve area continuity equation:

$\small \text{MVA} = \frac{A_{\text{LVOT}} \cdot \mathrm{VTI_{LVOT}}}{\mathrm{VTI_{MV}}}$

⚠️ Do NOT use in the presence of:

• Aortic regurgitation; or
• Mitral regurgitation.

They cause the transmitral and transaortic flows to differ!

## Other mitral valve area formulae

Let's explore other methods available in the mitral valve area calculator, beginning with the pressure half-time mitral valve area equation. It assumes that the gradient drop rate is proportional to the mitral stenosis severity and is given by:

$\small \text{MVA} = \frac{220}{\text{PHT}},$

where $\text{PHT}$ is the pressure half-time.

🔎 What if the Doppler spectrum isn't a distinct continuous slope? You may be dealing with concave tracing. Try approximating the best fit's slope and discarding the spectrum's initial part.

Pressure half-time is related to deceleration time, $\text{DT}$, by $\text{PHT} = 29\% \ \text{DT}$. Therefore, we can obtain the mitral valve area formula from deceleration time:

\small \begin{aligned} \text{MVA} &= \frac{220}{0.29 \cdot \text{DT}} \\[1.2em] &\approx \frac{759}{\text{DT}} \end{aligned}

⚠️ Do NOT use in the presence of:

• Aortic stenosis or heavily calcified leaflets;
• Aortic regurgitation;
• Diastolic dysfunction; or
• Post-valvuloplasty.

Two other formulae have their dedicated tools:

• PISA calculator – PISA stands for proximal isovelocity surface area. The limitation is the assumption that PISA is hemispheric, which is often not true.
• Gorlin formula calculator – Bear in mind that comorbidity of the mitral and aortic stenoses might lead to a low-flow state and unreliable results.

## Example: Using the mitral valve area calculator to estimate mitral stenosis severity

Let's finish with an example of how to calculate mitral valve area. Consider a patient for whom you find the following:

• LVOT diameter: $d_{\text{LVOT}} = 2.11 \text{ cm}$;
• LVOT velocity time integral: $\mathrm{VTI_{LVOT}} = 21.2 \text{ cm}$; and
• Mitral valve velocity time integral: $\mathrm{VTI_{MV}} = 74 \text{ cm}$.

The LVOT area is then:

\small \begin{aligned} A_{\text{LVOT}} &= \pi \left(\frac{1}{2}d_{\text{LVOT}}\right)^2 \\[1.2em] &= \pi \cdot 1.055^2 \approx 3.5 \ \mathrm{cm^2} \end{aligned}

And using the continuity equation, we find:

\small \begin{aligned} \text{MVA} &= \frac{A_{\text{LVOT}} \cdot \mathrm{VTI_{LVOT}}}{\mathrm{VTI_{MV}}} \\[1.2em] &= \frac{3.5 \cdot 21.2}{74} \approx 1 \ \mathrm{cm^2} \end{aligned}

This result agrees with the mitral valve area calculator numbers and may indicate moderate MS per the mitral stenosis criteria above.

## FAQ

### How do I calculate mitral valve area?

One way is to use the mitral valve area continuity equation:

1. Using Doppler echocardiography, find the left ventricular outflow tract (LVOT) diameter (dₗ), and velocity time integrals of LVOT (VTIₗ) and the mitral valve (VTIₘ).

2. Approximate the LVOT cross-sectional area (Aₗ) as:

π × (0.5 × dₗ)²

3. Plug the above results into the mitral valve area equation:

MVA = Aₗ × VTIₗ / VTIₘ,

where MVA is the mitral valve area.

### What is the mitral valve area of a patient with a deceleration time of 1000 ms?

The mitral valve area is approximately 0.76 cm2. We can tell this from the mitral valve area (MVA) equation MVA = 759/DT, where DT is the deceleration time.

### Are the mitral and bicuspid valve the same?

Yes and no. The mitral valve is often called a bicuspid valve because it usually has 2 cusps. However, this term is also used to refer to any valve for which this is true – for example, a bicuspid aortic valve is a common cardiac abnormality.

### How many mitral valves are there?

There is only one mitral valve in the human body, which is one of the four heart valves. The remaining three are called the aortic, tricuspid, and pulmonary valves.

Michael Darcy
Method
Continuity equation
LVOT diameter
cm
LVOT VTI
cm
Mitral valve VTI
cm
LVOT area
cm²
Mitral valve area (MVA)
cm²
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