Aortic Valve Continuity Equation Calculator With 3

Aortic Valve Continuity Equation:

\[ AVA = \frac{CSA_{LVOT} \times V_{LVOT}}{V_{Ao}} \]

Cross-Sectional Area of LVOT (CSA_LVOT):

cm²

Velocity in LVOT (V_LVOT):

m/s

Velocity in Aorta (V_Ao):

m/s

Aortic Valve Area (AVA):

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1. What is the Aortic Valve Continuity Equation?

The Aortic Valve Continuity Equation calculates the aortic valve area (AVA) using the principle of conservation of mass. It's based on measurements from echocardiography and is particularly useful for assessing aortic stenosis severity.

2. How Does the Calculator Work?

The calculator uses the continuity equation:

\[ AVA = \frac{CSA_{LVOT} \times V_{LVOT}}{V_{Ao}} \]

Where:

\( CSA_{LVOT} \) — Cross-sectional area of left ventricular outflow tract (cm²)
\( V_{LVOT} \) — Velocity time integral in LVOT (m/s)
\( V_{Ao} \) — Velocity time integral across aortic valve (m/s)

Explanation: The equation maintains that the stroke volume in the LVOT equals the stroke volume across the aortic valve.

3. Importance of AVA Calculation

Details: Accurate AVA measurement is essential for diagnosing and grading aortic stenosis severity, determining treatment options, and timing of valve replacement.

4. Using the Calculator

Tips: Enter all three parameters (CSA_LVOT, V_LVOT, and V_Ao) with appropriate units. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal aortic valve area?
A: Normal AVA is 3-4 cm². Severe aortic stenosis is typically defined as AVA <1.0 cm².

Q2: How is CSA_LVOT measured?
A: CSA_LVOT is calculated as π × (LVOT diameter/2)², measured in parasternal long-axis view.

Q3: What are common sources of error?
A: Errors in LVOT diameter measurement, non-circular LVOT, and misalignment of Doppler beam.

Q4: When is this equation not applicable?
A: In cases of subvalvular or supravalvular obstruction, or when LVOT flow is turbulent.

Q5: How does this compare to the Gorlin equation?
A: The continuity equation is non-invasive (echo-based) while Gorlin requires cardiac catheterization.