How to calculate AVA?

The aortic valve area (AVA) is calculated by dividing the left ventricular stroke volume (LV stroke volume) by the aortic valve velocity time integral (AV VTI).

Understanding the Components

To calculate AVA, we need two primary measurements:

1. Left Ventricular Stroke Volume (LV Stroke Volume): This is the volume of blood pumped out of the left ventricle with each heartbeat, measured in cubic centimeters (cm³).

2. Aortic Valve Velocity Time Integral (AV VTI): This is measured using continuous-wave Doppler during an echocardiogram. The AV VTI represents the distance blood travels through the aortic valve during systole, measured in centimeters (cm).

The Calculation

The formula for calculating AVA is straightforward:

AVA (cm²) = LV Stroke Volume (cm³) / AV VTI (cm)

Example Calculation

Let's assume:

• LV Stroke Volume = 70 cm³
• AV VTI = 20 cm

Then, the AVA would be calculated as follows:

AVA = 70 cm³ / 20 cm
AVA = 3.5 cm²

Practical Insights

• Echocardiography: The measurements required for this calculation are obtained through an echocardiogram. The LV stroke volume can be estimated through various methods within the echocardiography study.
• Doppler Use: The AV VTI is specifically measured using spectral Doppler with continuous wave mode during the echocardiogram.
• Clinical Significance: The calculated AVA helps in assessing the severity of aortic stenosis, a condition where the aortic valve narrows. A smaller AVA indicates more severe stenosis.

Steps Summarized

Here's a step-by-step summary of how to calculate AVA:

1. Measure LV Stroke Volume: Determine the volume of blood ejected from the left ventricle during systole using echocardiographic methods.
2. Measure AV VTI: Obtain the aortic valve velocity time integral using continuous-wave Doppler during an echocardiogram.
3. Apply the Formula: Divide the LV stroke volume by the AV VTI (AVA = LV Stroke Volume / AV VTI).
4. Interpret the Result: Evaluate the calculated AVA in conjunction with other clinical information to assess aortic valve function.

By following this procedure, clinicians can effectively assess aortic valve function and make informed decisions regarding patient care.