The Aortic Valve Area (AVA) is a crucial measurement used in cardiology to assess the severity of aortic stenosis, a condition where the aortic valve narrows, restricting blood flow from the heart to the rest of the body. Aortic stenosis can lead to symptoms like chest pain, shortness of breath, and fainting, and if severe, can be life-threatening.
Calculating the Aortic Valve Area helps clinicians determine the degree of obstruction and guide treatment decisions, which may range from watchful waiting to surgical valve replacement or transcatheter aortic valve implantation (TAVI).
How is Aortic Valve Area Calculated?
The most common and widely accepted method for calculating Aortic Valve Area non-invasively is using the Continuity Equation, derived from echocardiographic measurements. This principle states that the flow rate through one area of a tube must equal the flow rate through another area of the same tube, assuming no shunts or regurgitation.
The formula for the Continuity Equation is:
AVA = (LVOT Area × LVOT VTI) / Aortic VTI
Where:
- AVA: Aortic Valve Area (in cm²)
- LVOT Area: Left Ventricular Outflow Tract Area (in cm²)
- LVOT VTI: Left Ventricular Outflow Tract Velocity Time Integral (in cm)
- Aortic VTI: Aortic Valve Velocity Time Integral (in cm)
The LVOT Area itself is calculated from the LVOT Diameter:
LVOT Area = π × (LVOT Diameter / 2)² = 0.785 × (LVOT Diameter)²
Aortic Valve Area Calculator
Use the calculator below to determine the Aortic Valve Area based on your echocardiographic measurements. Enter the values for LVOT Diameter, LVOT VTI, and Aortic VTI in the specified units.
Result:
Interpreting Your Aortic Valve Area Results
The calculated Aortic Valve Area helps classify the severity of aortic stenosis:
- Normal: > 2.0 cm²
- Mild Aortic Stenosis: 1.5 – 2.0 cm²
- Moderate Aortic Stenosis: 1.0 – 1.5 cm²
- Severe Aortic Stenosis: < 1.0 cm²
- Critical Aortic Stenosis: < 0.6 cm² (often associated with very high gradients)
It's important to note that AVA should always be interpreted in conjunction with other echocardiographic parameters (like mean pressure gradient, peak velocity, and left ventricular function) and the patient's clinical symptoms. This calculator is for informational purposes only and should not be used for self-diagnosis or to replace professional medical advice.
function calculateAVA() { var lvotDiameter = parseFloat(document.getElementById("lvotDiameter").value); var lvotVTI = parseFloat(document.getElementById("lvotVTI").value); var aorticVTI = parseFloat(document.getElementById("aorticVTI").value); var resultDiv = document.getElementById("result"); // Input validation if (isNaN(lvotDiameter) || lvotDiameter <= 0) { resultDiv.innerHTML = "Please enter a valid positive number for LVOT Diameter."; return; } if (isNaN(lvotVTI) || lvotVTI <= 0) { resultDiv.innerHTML = "Please enter a valid positive number for LVOT VTI."; return; } if (isNaN(aorticVTI) || aorticVTI <= 0) { resultDiv.innerHTML = "Please enter a valid positive number for Aortic VTI."; return; } // Calculate LVOT Area var lvotArea = 0.785 * Math.pow(lvotDiameter, 2); // Using 0.785 for pi/4 // Calculate Aortic Valve Area (AVA) var ava = (lvotArea * lvotVTI) / aorticVTI; // Display result resultDiv.innerHTML = "