1. What is the Aortic Valve Dimensionless Index?

The Aortic Valve Dimensionless Index (DVI) is a ratio used to assess aortic valve function by comparing transmitral velocity to left ventricular outflow tract velocity. It provides a simple and effective method for evaluating valve performance without the need for complex measurements.

2. How Does the Calculator Work?

The calculator uses the DVI formula:

Where:

• \( V_{ti} \) — Transmitral velocity (m/s)
• \( V_{lvot} \) — Left ventricular outflow tract velocity (m/s)

Explanation: The DVI ratio helps assess the relative obstruction across the aortic valve, with lower values indicating more significant stenosis.

3. Importance of DVI Calculation

Details: DVI is particularly useful in patients with low flow states or when other parameters like valve area calculations may be unreliable. It remains relatively constant across different flow conditions.

4. Using the Calculator

Tips: Enter both velocity measurements in meters per second (m/s). Ensure measurements are taken during the same cardiac cycle for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What is the normal range for DVI?
A: Normal DVI values are typically >0.25. Values below 0.25 suggest significant aortic stenosis.

Q2: Why is DVI considered "dimensionless"?
A: DVI is dimensionless because it's a ratio of two velocities (both in m/s), so the units cancel out.

Q3: When is DVI most useful?
A: DVI is particularly valuable in low-flow, low-gradient aortic stenosis and when ejection fraction is reduced.

Q4: How does DVI compare to other aortic stenosis indices?
A: DVI correlates well with valve area but is less flow-dependent, making it more reliable in certain clinical scenarios.

Q5: Are there limitations to using DVI?
A: DVI may be less accurate in the presence of significant mitral regurgitation or when there are technical difficulties in obtaining accurate velocity measurements.