Free EROA - Mitral Regurgitation Calculator

Radius (r)

Aliasing Speed (Va)

Maximal Velocity (Vmax)

Velocity Time Integral (VTI)

Enter echocardiography parameters to calculate EROA

Understanding Mitral Regurgitation and the Role of EROA Assessment

Mitral regurgitation (MR) is a valvular disorder where the mitral valve fails to close completely during left ventricular systole, allowing blood to flow backward into the left atrium. Quantifying MR severity is essential for clinical decisions, and the effective regurgitant orifice area (EROA) derived from the proximal isovelocity surface area (PISA) method serves as a key metric. This online mitral regurgitation calculator, designed as both an EROA calculator and a PISA calculator, automatically computes EROA, regurgitant volume, volume flow rate, and the corresponding ACC/AHA stage from four standard echocardiographic inputs. It can assist cardiologists, sonographers, and trainees in applying the PISA technique consistently in everyday practice.

What Is Mitral Regurgitation?

In a healthy heart, the mitral valve closes exactly when the left ventricle contracts, directing oxygenated blood into the aorta. In MR, the valve leaflets do not coapt fully, leaving an orifice that permits retrograde leakage. The size of this orifice, known as the effective regurgitant orifice area (EROA), directly influences the volume of blood that regurgitates and the hemodynamic load on the left heart.

MR is not a standalone disease but a condition arising from various underlying pathologies. It is broadly classified as chronic or acute, each with distinct causes, presentation, and outcomes.

Causes of Mitral Regurgitation

Chronic MR typically evolves over years and can be triggered by:

Rheumatic fever causing valvular scarring and commissural fusion
Degenerative changes of the mitral apparatus, including mitral valve prolapse (often associated with hypertension or myxomatous degeneration)
Connective tissue disorders such as Marfan syndrome, Ehlers‑Danlos syndrome, or systemic lupus erythematosus (SLE)
Infective endocarditis, which may destroy leaflet tissue
Coronary artery disease leading to ischemic papillary muscle dysfunction
Cardiomyopathies that alter ventricular geometry and tether the leaflets
Genetic predisposition
Drug‑related causes, for example ergotamine derivatives

Acute MR presents suddenly and can result from:

Infective endocarditis with leaflet perforation or rupture
Mechanical injury during intravenous procedures or catheter interventions
Acute myocardial infarction affecting papillary muscle function or causing rupture
Rapid exacerbation of any chronic cause, such as acute chordal rupture in myxomatous degeneration

Symptoms and Clinical Presentation

Mild chronic MR may remain entirely asymptomatic and be discovered only during a routine echocardiogram. When symptoms do appear, especially in acute MR, they can include:

Reduced exercise tolerance and easy fatigability
Shortness of breath, which may be exertional or occur at rest
Palpitations or a sensation of rapid heartbeats
A holosystolic murmur audible with a stethoscope

Symptom severity is often more closely tied to the patient’s hemodynamic reserve than to the absolute degree of regurgitation. Some individuals tolerate severe MR for years, while acute MR rapidly leads to pulmonary congestion and hemodynamic instability.

Echocardiographic Findings

Echocardiography (ECHO) is the definitive tool for diagnosing and grading MR. Typical sonographic features include:

A distinct regurgitant jet on color Doppler, flowing back into the left atrium, which is the primary sign
An identifiable coaptation gap between the anterior and posterior mitral leaflets; the gap width correlates with MR severity
Visualization of the underlying cause, such as leaflet prolapse, vegetations, flail segments, or papillary muscle abnormalities
Secondary signs like left atrial enlargement, left ventricular remodeling, and pulmonary vein flow reversal

The PISA method uses the hemispheric convergence zone visible on color Doppler to calculate volume flow rate and EROA.

How to Use the EROA Calculator

To obtain results from this echocardiography calculator, you need four measurements from a comprehensive Doppler ECHO exam:

Radius (r) – the radius of the proximal isovelocity surface area, in centimeters
Aliasing velocity (Va) – the color Doppler aliasing velocity at the PISA, in cm/s
Maximal velocity (Vmax) – the peak velocity of the continuous‑wave MR jet, in cm/s
Velocity time integral (VTI) – the velocity‑time integral of the MR jet, in centimeters

Enter these values into the calculator. The tool immediately computes the following parameters:

Volume Flow Rate (VFR)

The flow rate through the PISA shell is given by:

VFR = 2 \pi r^{2} V_{a}

The result is expressed in milliliters per second (mL/s) and represents the instantaneous regurgitant flow.

Effective Regurgitant Orifice Area (EROA)

Applying the continuity principle, the cross‑sectional area of the regurgitant orifice is obtained by dividing VFR by the peak MR velocity:

EROA = \frac{VFR}{V_{max}}

EROA is reported in square centimeters ( $cm^{2}$ ) and directly determines the MR grade.

Regurgitant Volume (RVol)

The total volume of blood that leaks back into the left atrium with each heartbeat is derived by multiplying EROA by the velocity time integral of the MR jet:

RVol = EROA \times VTI \quad (\text{in mL})

Together, these three parameters give a comprehensive hemodynamic profile of the regurgitant lesion.

ACC/AHA Integrated Staging

Although EROA‑based grading is widely used, the American College of Cardiology and American Heart Association (ACC/AHA) recommend a more integrated staging that incorporates symptoms and multiple Doppler measures. The table below summarizes the main thresholds:

Stage	Description	EROA ( $cm^{2}$ )	Regurgitant Volume (mL)	Vena Contracta (cm)	Jet Area (% LA)
A	At risk for MR	–	–	<0.3	<20% (or small central jet)
B	Progressive MR	<0.4	<60	<0.7	20–40%
C	Asymptomatic severe MR	$\ge 0.4$	$\ge 60$	$\ge 0.7$	>40% (or holosystolic eccentric jet)
D	Symptomatic severe MR	$\ge 0.4$	$\ge 60$	$\ge 0.7$	>40% (or holosystolic eccentric jet)

In stages C and D the regurgitant fraction also exceeds 50% and the angiographic grade is 3+ or higher. The critical distinction between C and D is the presence of symptoms—decreased exercise tolerance, exertional dyspnea, or signs of heart failure—which by themselves classify the MR as severe.

Coexisting Mitral and Tricuspid Regurgitation

It is possible for a patient to have both mitral and tricuspid valve regurgitation simultaneously. This combination is more common in ischemic MR (due to coronary artery disease) and in rheumatic heart disease. Usually, mitral regurgitation appears first, with tricuspid regurgitation developing months or years later as right ventricular pressure overload increases. The prognosis for individuals with dual valve disease is guarded; they face higher risks of heart failure, reduced functional capacity, and shortened survival.

Clinical Caveats

While this PISA‑based calculator provides rapid objective quantification, it should not replace a thorough clinical evaluation. All calculated values must be interpreted in the context of the patient’s symptoms, physical examination, and additional imaging. Decisions about medical therapy, surgical repair, or valve replacement should be made by a qualified cardiologist or heart team.

FAQ

1. What are the main causes of chronic mitral regurgitation?

Chronic mitral regurgitation is most often caused by rheumatic fever, degenerative changes (including mitral valve prolapse), connective tissue disorders (e.g., Marfan syndrome, Ehlers‑Danlos syndrome, SLE), infective endocarditis, coronary artery disease, cardiomyopathies, genetic factors, and certain drugs like ergotamine.

2. How is EROA calculated using the PISA method?

First, measure the PISA radius (r) and aliasing velocity (Va) on color Doppler. Compute the volume flow rate (VFR = 2πr² × Va). Then obtain the peak MR jet velocity (Vmax) from continuous‑wave Doppler. The effective regurgitant orifice area is given by EROA = VFR / Vmax.

3. What is the difference between ACC/AHA Stage C and Stage D mitral regurgitation?

Both stages share the same severe criteria: EROA ≥0.4 cm², regurgitant volume ≥60 mL, vena contracta ≥0.7 cm, jet area >40% LA, and regurgitant fraction ≥50%. The only difference is that Stage D patients are symptomatic (e.g., dyspnea, reduced exercise tolerance), while Stage C patients are asymptomatic.

4. Can mitral regurgitation and tricuspid regurgitation occur together?

Yes, it is possible, especially in patients with ischemic mitral regurgitation (due to coronary artery disease) or rheumatic heart disease. Typically mitral regurgitation develops first, and tricuspid regurgitation follows later. The combination is associated with a worse prognosis.

5. What measurements do I need to enter into the EROA calculator?

You need four values from an echocardiogram: the PISA radius (cm), aliasing velocity (cm/s), peak MR jet velocity (cm/s), and the velocity time integral (VTI) of the MR jet (cm). The calculator then outputs the volume flow rate, EROA, regurgitant volume, and the ACC/AHA stage.

How to Use

Enter the radius (r) of the PISA (Proximal Isovelocity Surface Area) from your ECHO results.
Enter the aliasing speed (Va), maximal velocity (Vmax), and velocity time integral (VTI) from the ECHO examination.
Read the calculated VFR, EROA, and regurgitant volume (Rvol) instantly, along with the mitral regurgitation severity grade.