1. What is Bazett's Formula?

Bazett's formula is used to calculate the corrected QT interval (QTc) which accounts for heart rate variations. It is particularly recommended for infants and children. A normal QTc is typically less than 440 ms in children.

2. How Does the Calculator Work?

The calculator uses Bazett's formula:

Where:

• \( QT \) — QT interval measured from start of Q wave to end of T wave (ms)
• \( RR \) — RR interval calculated as 60 / HR (seconds)
• \( HR \) — Heart rate (beats per minute)

Explanation: The formula corrects the measured QT interval for heart rate, providing a standardized value that can be compared across different heart rates.

3. Importance of QTc Calculation

Details: Accurate QTc calculation is crucial for detecting prolonged QT intervals which may indicate increased risk of life-threatening arrhythmias. It is particularly important in pediatric cardiology for screening and monitoring.

4. Using the Calculator

Tips: Enter QT interval in milliseconds and heart rate in beats per minute. Both values must be positive numbers. The calculator will compute the corrected QT interval using Bazett's formula.

5. Frequently Asked Questions (FAQ)

Q1: Why use Bazett's formula for children?
A: Bazett's formula is specifically recommended for infants and children as it provides the most accurate correction for heart rate in pediatric populations.

Q2: What is a normal QTc value in children?
A: A normal QTc is generally considered to be less than 440 ms in children. Values above this may indicate prolonged QT syndrome.

Q3: How is the QT interval measured?
A: The QT interval is measured from the beginning of the QRS complex to the end of the T wave on an electrocardiogram (ECG).

Q4: Are there limitations to Bazett's formula?
A: While excellent for children, Bazett's formula may overcorrect at very high heart rates and undercorrect at very low heart rates in some populations.

Q5: When should QTc be measured?
A: QTc should be measured during routine ECG examinations, especially in children with family history of sudden cardiac death or those taking medications that may prolong QT interval.