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EROA - Mitral Regurgitation Calculator

Table of contents

What is mitral regurgitation?Causes of mitral regurgitationMitral regurgitation symptomsWhat does a mitral regurgitation look like on ECHO?How to use the EROA mitral regurgitation calculator?Degrees of mitral regurgitation - grades 1, 2, 3, 4Is both mitral and tricuspid regurgitation possible?FAQs

The EROA mitral regurgitation calculator is a tool for anyone interested in learning more about this disease of the heart's left valve. With the tool, you'll not only count the EROA (Effective Regurgitant Orifice Area), but will also find out what causes mitral regurgitation, what the possible symptoms are, and what it looks like on ECHO. Ever wondered if both mitral and tricuspid regurgitation is possible? Read on to find out!

We try our best to make our Omni Calculators as precise and reliable as possible. However, this EROA mitral regurgitation calculator can never replace a professional doctor's assessment. Before administering any drugs, fluids, or treatment to your patient, make sure you know the correct dose and method.

What is mitral regurgitation?

Mitral regurgitation is a state where the mitral valve of the heart does not behave correctly and so begins to leak blood from the left ventricle to the left atrium.

When healthy, the mitral valve closes the exact moment the left ventricle contracts during a heart beat. In that way, all the oxygenated blood can flow into the aorta and nourish our organs. When mitral regurgitation appears, the valve doesn't close completely. During left ventricle contraction, some of the blood portion moves back to the left atrium - and less blood is moved into the aorta.

Pictures of a healthy heart, and a heart with mitral regurgitation, with differences and blood flow directions explained
Comparison of a healthy heart and a heart with mitral regurgitation

Causes of mitral regurgitation

Mitral regurgitation is not usually a disease on its own but rather a condition due to underlying causes. We can differentiate chronic and acute mitral regurgitation. They have different causes and prognoses.

For the chronic state, causes of mitral regurgitation include:

  • Rheumatic fever affecting the heart;
  • Degenerative lesions of the mitral valve (e.g., due to hypertension);
  • Connective tissue disorders - e.g., Marfan's syndrome, Ehlers-Danlos syndrome, SLE (Systemic Lupus Erythematosus);
  • Infective endocarditits;
  • Coronary artery disease;
  • Heart conditions - cardiomyopathies;
  • Genetic predispositions; and
  • Drugs, like ergotamine.

Acute mitral regurgitation can be caused by:

  • Infective endocarditis;
  • Injuries, e.g., during an intravenous procedure;
  • Acute myocardial infarction; and
  • All of the processes that can cause chronic regurgitation when they're sudden or exacerbated.

Mitral regurgitation symptoms

Some mitral regurgitations will show no symptoms and stay 'quiet' until they're found incidentally on an echocardiogram. The others, primarily acute ones, will directly cause hospitalization or surgery.

Mitral regurgitation symptoms may include:

  • Physical activity intolerance or easy tiredness;
  • Shortness of breath;
  • Heart palpitations or fast heart beating; and
  • Heart murmurs, heard with a stethoscope.

The interesting thing is that the symptoms are correlated with the body's tolerance to hemodynamic changes, rather than with the severity of the mitral regurgitation.

What does a mitral regurgitation look like on ECHO?

Imaging a mitral regurgitation on ECHO (echocardiogram) allows for the final diagnosis and precise assessment. While your symptoms and the clinical signs you're showing may suggest that you have a problem with the mitral valve, you still need an imaging method to prove it conclusively. Doctors use an ECHO examination for that. It is a type of ultrasound method that checks the internal organs.

The mitral regurgitation on ECHO shows:

  • A regurgitant jet - the wave that comes back into the left atrium - the primary sign.
  • An orifice in the mitral valve area - valve's cusps not touching each other tightly. The loss size depends on the degree of mitral regurgitation.
  • The cause of mitral regurgitation - like vegetation, lesions to the papillary muscles, or chordae tendineae.
  • Sometimes signs of the underlying cause and the aftereffects, like heart disease or left ventricle remodeling.

How to use the EROA mitral regurgitation calculator?

To use the EROA calculator, first, you need to have conducted your ECHO (echocardiogram). It is a safe, non-intrusive examination that is basically an ultrasound of your heart. However, it takes some practice to perform an ECHO correctly.

Once you've got your results, you need to pay attention to the four parameters:

  • Radius (cm by default) - Radius of PISA (Proximal Isovelocity Surface Area);
  • Aliasing velocity (cm/s by default) - Measured at a radial distance;
  • Maximal velocity (cm/s by default) - Peak velocity of mitral regurgitation; and
  • Velocity time integral (cm by default) - Of the mitral regurgitant jet.
  1. Type them all into the EROA mitral regurgitation calculator panel.
  2. When you're done, the results will be ready immediately. You will see the following:
    • The volume flow rate - VFR (ml/s by default).
    • The effective regurgitant orifice - EROA (cm2 by default). The EROA formula tells us how big the 'hole' that lasts after the valve tries to close; it also defines the mitral regurgitation grade - 1, 2, 3, or 4.
    • The regurgitant volume - Rvol (ml by default). It says how much blood comes backwards into the left atrium with each heart beat; it defines the volume overload.
  3. You will also get some information on the stage of mitral regurgitation below the fields of the EROA mitral regurgitation calculator.

If you're interested in echocardiography, find out more in our tools:

Degrees of mitral regurgitation - grades 1, 2, 3, 4

Although the EROA mitral valve assessment is validated and widely used, it is not the only way of estimating EROA mitral regurgitation. A more integrated approach was proposed by the ACC/AHA (American College of Cardiology and American Heart Association) joint committee in 2014. You might notice it takes symptoms into account, and any mitral valve dysfunction that is symptomatic is classified as 'severe' right away.

  1. Grade A - at risk of MR, no symptoms
  • No MR jet or small central jet area <20% LA on Doppler; and
  • Vena contracta <0.3 cm.

MR - mitral regurgitation; LA - left atrium; EROA - effective regurgitant orifice area.

  1. Grade B - progressive MR, no symptoms
  • Central jet 20-40% LA or late systolic eccentric jet MR;
  • Vena contracta <0.7 cm;
  • Regurgitant volume <60 mL;
  • Regurgitant fraction <50%;
  • EROA <0.4 cm2; and
  • Angiographic grade 1-2+.
  1. Grade C - asymptomatic severe MR
  • Central jet >40% LA or holosystolic eccentric jet MR;
  • Vena contracta ⩾0.7 cm;
  • Regurgitant volume ⩾60 mL;
  • Regurgitant fraction ⩾50%;
  • EROA ⩾0.4 cm2; and
  • Angiographic grade 3-4+.
  1. Grade D - symptomatic severe MR
  • Central jet >40% LA or holosystolic eccentric jet MR;
  • Vena contracta ⩾0.7 cm;
  • Regurgitant volume ⩾60 mL;
  • Regurgitant fraction ⩾50%,
  • EROA ⩾0.4 cm2;
  • Angiographic grade 3-4+;
  • Decreased exercise tolerance; and
  • Exertional dyspnea.

Is both mitral and tricuspid regurgitation possible?

Yes, it is possible to have two valve defects simultaneously.

It is more common in patients with ischaemic mitral valve regurgitation (lesion due to coronary artery disease) and patients suffering from rheumatic fever. Usually, the first to appear is mitral valve regurgitation, then after some time (months or years), the tricuspid disorder shows up.

The prognosis for patients with both mitral and tricuspid regurgitation is poor. The defects often lead to heart failure, impaired physical activity intolerance, and a shortened lifespan.


What is the most common cause of mitral regurgitation?

The most common cause of mitral regurgitation is a mitral valve prolapse. Mitral valve prolapse means that the cusps (leaflets) bulge into the left atrium during the heart contraction. It is a fairly common condition, and not every prolapse will lead to regurgitation. Most people will live their lives with prolapse, not even knowing about it.

How do I calculate ERO on ECHO?

To calculate EROA for mitral valve (effective regurgitant orifice area):

  1. Find the value of the radius of the orifice (r) and aliasing speed (Va) on ECHO.
  2. Calculate the VFR (volume flow rate) with the formula:

VFR = 2 × π × r2 × Va

  1. Find the value of Vmax (maximal velocity) on ECHO.
  2. Estimate the result using the EROA formula:

ERO = VFR/Vmax

  1. Congratulate yourself on calculating EROA.

How common is mitral regurgitation?

Up to 70 % of adults might have mitral regurgitation.

The most common form is a trace, asymptomatic mitral insufficiency. Most people will live their life not even knowing about it. Significant (moderate to severe) mitral regurgitation is much less common and will occur in 3-10% of the general population.

How do you treat mitral regurgitation?

The best treatment of choice is cardiac surgery - repair or total replacement of the mitral valve.

Your doctor might prescribe you drugs to alleviate the symptoms and treat underlying causes. Still, these will not affect the mechanical defect of the valve if it is already there. The medications can also slow down the disease's progression.

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