1. What is EOA Aortic Valve?

The Effective Orifice Area (EOA) of the aortic valve is a measure of the functional area available for blood flow through the valve. It's calculated using the continuity equation based on echocardiographic measurements.

2. How Does the Calculator Work?

The calculator uses the continuity equation:

Where:

• \( LVOT\ Area \) — Left ventricular outflow tract area (cm²)
• \( VTI\ LVOT \) — Velocity time integral at the LVOT (cm)
• \( VTI\ AV \) — Velocity time integral at the aortic valve (cm)

Explanation: The equation is based on the principle of continuity of flow, where the stroke volume at the LVOT equals the stroke volume through the aortic valve.

3. Importance of EOA Calculation

Details: EOA is crucial for assessing aortic valve stenosis severity. It helps differentiate true stenosis from pseudo-stenosis and guides treatment decisions.

4. Using the Calculator

Tips: Enter LVOT Area in cm², VTI LVOT in cm, and VTI AV in cm. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal EOA value?
A: Normal aortic valve area is 3-4 cm². Values <1 cm² indicate severe stenosis, 1-1.5 cm² moderate, and >1.5 cm² mild.

Q2: How does EOA differ from anatomic area?
A: EOA represents the functional area, which is typically smaller than the anatomic area due to flow contraction through the valve.

Q3: When is this calculation most useful?
A: Particularly valuable in low-flow, low-gradient aortic stenosis where ejection fraction may be reduced.

Q4: What are limitations of this method?
A: Accuracy depends on proper measurement of LVOT diameter and correct alignment of Doppler signals.

Q5: How does EOA relate to patient symptoms?
A: Symptoms typically occur when EOA <1 cm², though symptoms may appear earlier in small individuals (indexed EOA <0.6 cm²/m²).