1. What is Aortic Valve EOA?

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 crucial for assessing the severity of aortic stenosis and guiding treatment decisions.

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 LVOT (cm)
• \( VTI\ AV \) — Velocity time integral at aortic valve (cm)

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

3. Importance of EOA Calculation

Details: EOA measurement is essential for classifying aortic stenosis severity (mild, moderate, severe) and determining the need for valve replacement. Age-adjusted values are particularly important in elderly patients.

4. Using the Calculator

Tips: Enter LVOT area in cm², VTI values in cm, and age in years. All values must be positive numbers. Age helps in interpreting the results in clinical context.

5. Frequently Asked Questions (FAQ)

Q1: What are normal EOA values?
A: Normal aortic valve EOA is typically 3-4 cm². Values <1.0 cm² usually indicate severe stenosis, but interpretation should consider body size (indexed to BSA).

Q2: How does age affect EOA interpretation?
A: EOA naturally decreases with age due to calcification. Age-specific reference ranges should be considered, especially in elderly patients.

Q3: When is this calculation most useful?
A: Particularly valuable in low-flow, low-gradient aortic stenosis cases to distinguish true stenosis from pseudo-stenosis.

Q4: What are limitations of this method?
A: Accuracy depends on precise measurement of LVOT diameter (squared in area calculation) and proper Doppler alignment.

Q5: Should EOA be indexed to body size?
A: Yes, for patients at extremes of body size, EOA should be indexed to body surface area (EOAi = EOA/BSA).