1. What is Aortic Size Index?

The Aortic Size Index (ASI) is a measurement that indexes aortic root size to body surface area. It provides a normalized assessment of aortic dimensions that accounts for patient body size, making it more accurate than absolute aortic diameter measurements alone.

2. How Does the Calculator Work?

The calculator uses the ASI formula:

Where:

• \( Aortic\ Diameter \) — Maximum aortic root diameter in centimeters
• \( BSA \) — Body Surface Area in square meters

Explanation: The equation normalizes aortic size to body surface area, allowing for better comparison across patients of different sizes and more accurate assessment of aortic dilation.

3. Importance of ASI Calculation

Details: ASI is crucial for evaluating aortic root dilation, assessing risk of aortic complications, monitoring patients with connective tissue disorders, and guiding surgical decision-making for aortic root replacement.

4. Using the Calculator

Tips: Enter aortic diameter in centimeters and body surface area in square meters. Both values must be positive numbers. BSA can be calculated using standard formulas like Du Bois or Mosteller.

5. Frequently Asked Questions (FAQ)

Q1: What is the clinical significance of ASI?
A: ASI helps identify true aortic dilation independent of body size, with values >2.1 cm/m² indicating increased risk of aortic complications.

Q2: How is aortic diameter measured?
A: Typically measured at the sinuses of Valsalva using echocardiography, CT, or MRI in end-diastole.

Q3: What are normal ASI values?
A: Normal ASI is generally <2.0 cm/m². Values between 2.0-2.4 cm/m² suggest mild dilation, and >2.4 cm/m² indicates significant dilation.

Q4: Why use ASI instead of absolute diameter?
A: ASI accounts for body size differences, making it more accurate for risk stratification, especially in smaller or larger individuals.

Q5: When should ASI be used?
A: Particularly important in Marfan syndrome, bicuspid aortic valve, and other conditions predisposing to aortic dilation.