Eoa Index Aortic Valve Calculator

Effective Orifice Area Equation:

\[ EOA = \frac{SV}{VTI_{aortic}} \times \frac{CSA_{lvot}}{VTI_{lvot}} \]

Stroke Volume (SV):

Aortic Valve VTI:

LVOT Cross-sectional Area:

cm²

LVOT VTI:

Effective Orifice Area (EOA):

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1. What is the Effective Orifice Area (EOA)?

The Effective Orifice Area (EOA) is a hemodynamic parameter used to assess the functional area of prosthetic heart valves or stenotic native valves. It represents the cross-sectional area through which blood actually flows during systole.

2. How Does the Calculator Work?

The calculator uses the EOA equation:

\[ EOA = \frac{SV}{VTI_{aortic}} \times \frac{CSA_{lvot}}{VTI_{lvot}} \]

Where:

\( SV \) — Stroke Volume (mL)
\( VTI_{aortic} \) — Aortic Valve Velocity Time Integral (cm)
\( CSA_{lvot} \) — Left Ventricular Outflow Tract Cross-sectional Area (cm²)
\( VTI_{lvot} \) — Left Ventricular Outflow Tract Velocity Time Integral (cm)

Explanation: This equation calculates the effective orifice area by combining flow measurements from both the aortic valve and left ventricular outflow tract.

3. Importance of EOA Calculation

Details: EOA measurement is crucial for evaluating prosthetic valve function, detecting patient-prosthesis mismatch, and assessing the severity of aortic stenosis. It provides important prognostic information and guides clinical management decisions.

4. Using the Calculator

Tips: Enter all four required parameters measured from echocardiography. Ensure values are in the correct units: SV in mL, VTI measurements in cm, and CSA in cm². All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal EOA value for aortic valves?
A: Normal native aortic valve EOA is typically 3.0-4.0 cm². For prosthetic valves, expected EOA varies by valve type and size, generally ranging from 1.0-2.5 cm².

Q2: What constitutes patient-prosthesis mismatch?
A: Patient-prosthesis mismatch occurs when the EOA of the prosthetic valve is too small for the patient's body size, typically defined as an indexed EOA < 0.85 cm²/m².

Q3: How does EOA differ from geometric orifice area?
A: EOA represents the functional flow area, which is smaller than the geometric orifice area due to flow contraction and pressure recovery effects.

Q4: When should EOA be measured?
A: EOA should be measured during routine echocardiographic evaluation of prosthetic valves and in patients with suspected aortic stenosis to assess severity and guide treatment decisions.

Q5: What are limitations of EOA calculation?
A: Limitations include measurement variability, assumptions about circular LVOT geometry, and potential inaccuracies in low-flow states or with irregular heart rhythms.