Dimensional Index Aortic Valve Calculator

Dimensional Index Formula:

\[ DI = \frac{VTI_{LVOT}}{VTI_{Ao}} \]

Dimensional Index (DI):

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1. What is Dimensional Index?

The Dimensional Index (DI) is a dimensionless parameter used in echocardiography to assess aortic valve function. It represents the ratio of left ventricular outflow tract velocity time integral to aortic velocity time integral, providing valuable information about valvular hemodynamics.

2. How Does the Calculator Work?

The calculator uses the Dimensional Index formula:

\[ DI = \frac{VTI_{LVOT}}{VTI_{Ao}} \]

Where:

\( VTI_{LVOT} \) — Velocity Time Integral of Left Ventricular Outflow Tract (cm)
\( VTI_{Ao} \) — Velocity Time Integral of Aortic Valve (cm)
\( DI \) — Dimensional Index (unitless)

Explanation: The Dimensional Index compares the flow velocities before and across the aortic valve, helping to evaluate valve function and potential obstructions.

3. Clinical Significance

Details: The Dimensional Index is particularly useful in assessing aortic stenosis severity, differentiating between true and pseudo-severe stenosis, and evaluating prosthetic valve function. Lower values typically indicate more significant obstruction.

4. Using the Calculator

Tips: Enter both VTI values in centimeters. Ensure measurements are taken from appropriate Doppler signals - VTI_LVOT from pulsed-wave Doppler and VTI_Ao from continuous-wave Doppler across the aortic valve.

5. Frequently Asked Questions (FAQ)

Q1: What is the normal range for Dimensional Index?
A: Normal Dimensional Index values typically range from 0.25 to 0.50, but interpretation depends on the clinical context and other echocardiographic parameters.

Q2: How does DI relate to aortic valve area?
A: DI is inversely related to the severity of aortic stenosis. Lower DI values generally correspond to smaller effective orifice areas and more severe stenosis.

Q3: When is DI most clinically useful?
A: DI is particularly valuable in low-flow, low-gradient aortic stenosis and in assessing prosthetic valve function where traditional parameters may be less reliable.

Q4: What are the limitations of DI?
A: DI can be affected by suboptimal Doppler alignment, arrhythmias, and significant concomitant valve disease. It should be interpreted in conjunction with other echocardiographic data.

Q5: How does DI compare to other aortic stenosis indices?
A: DI provides complementary information to traditional parameters like peak velocity, mean gradient, and valve area by offering a flow-independent assessment of stenosis severity.