EROA - Mitral Regurgitation Calculator
Created by Kaushik RabadiyaLast updated: September 24, 2026EROA instantly calculates results using aliasing speed, effective regurgitant orifice area, radius. Use the calculator above for instant answers in your browser.
Welcome to the EROA (Effective Regurgitant Orifice Area) Calculator, a specialized clinical tool designed for cardiologists, sonographers, and medical professionals. By evaluating color Doppler parameters from an echocardiogram, this calculator quantifies the severity of mitral regurgitation to help guide patient prognosis and therapeutic interventions.
How the EROA Calculation Works
The calculation relies on the proximal isovelocity surface area (PISA) method. First, the volume flow rate is determined using the hemispheric surface area equation: Q = 2 * pi * r^2 * v_alias, where 'r' is the proximal flow convergence radius and 'v_alias' is the aliasing velocity. Next, the Effective Regurgitant Orifice Area (EROA) is calculated by dividing the volume flow rate by the peak regurgitant velocity: EROA = Q / v_max. Finally, the total regurgitant volume (RVol) can be estimated by multiplying EROA by the velocity-time integral (VTI) of the regurgitant jet.
Worked Clinical Example
Consider an echocardiogram showing a proximal flow convergence radius of 0.9 cm with an aliasing velocity of 40 cm/s (0.4 m/s). First, calculate the volume flow rate: Q = 2 * 3.14159 * (0.9)^2 * 40 = 203.58 cm^3/s. Next, if the peak mitral regurgitation velocity (v_max) is measured at 500 cm/s, we find EROA = 203.58 / 500 = 0.407 cm^2. If the regurgitant VTI is 100 cm, multiplying EROA by VTI yields a regurgitant volume of approximately 40.7 mL per beat, indicating severe mitral regurgitation.
Clinical Best Practices & Pitfalls
Ensure that the Nyquist limit (aliasing velocity) is optimized and clearly visible during image acquisition to avoid sizing errors in the PISA radius. Always measure the radius along the central axis of the flow convergence zone perpendicular to the leaflet surface. Be mindful that eccentric jets can underestimate the true orifice area when using standard hemispheric assumptions.
FAQs
What is the most common cause of mitral regurgitation?
The most frequent cause of chronic primary mitral regurgitation in developed countries is mitral valve prolapse, often driven by myxomatous degeneration. In developing regions, rheumatic heart disease remains a leading contributor. Secondary or functional mitral regurgitation typically stems from left ventricular remodeling due to ischemic heart disease or dilated cardiomyopathy.
How do I calculate ERO on ECHO?
Effective Regurgitant Orifice (ERO) is calculated on an echocardiogram using the Proximal Isovelocity Surface Area (PISA) method. You measure the radius of the hemispheric shell of flow convergence, multiply it by the aliasing velocity and two pi, and then divide that resulting volume flow rate by the peak velocity of the regurgitant jet.
How common is mitral regurgitation?
Mitral regurgitation is one of the most prevalent forms of valvular heart disease globally. Its prevalence increases significantly with age, affecting a small percentage of young adults but rising to affect over ten percent of individuals aged 75 and older, making accurate grading essential for geriatric and general cardiology.
How do you treat mitral regurgitation?
Treatment depends heavily on the severity, etiology, and whether the patient is symptomatic. Mild cases may only require active clinical surveillance. Severe symptomatic cases often require surgical intervention, such as mitral valve repair or replacement, or minimally invasive catheter-based edge-to-edge repair procedures for high-risk patients.
Based on 2 sources
- Quantitation of mitral regurgitation — Grayburn, P. A., Weissman, N. J., & Zamorano, J. L.
- 2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines — Nishimura, R. A., Otto, C. M., Bonow, R. O., Carabello, B. A., Erwin, J. P., 3rd, Guyton, R. A., O'Gara, P. T., Ruiz, C. E., Skubas, N. J., Sorajja, P., Sundt, T. M., 3rd, Thomas, J. D., & ACC/AHA Task Force Members
Formula verified against WHO/CDC clinical references — all calculations use deterministic, standards-based formulas.
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