1. What is Bazett's Formula?

Bazett's formula is used to calculate the corrected QT interval (QTc) which accounts for variations in heart rate. It provides a standardized measure of ventricular repolarization that is independent of heart rate.

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 by dividing by the square root of the RR interval.

3. Importance of QTc Calculation

Details: Accurate QTc calculation is crucial for assessing cardiac repolarization abnormalities, identifying risk of arrhythmias, and monitoring drug effects on cardiac conduction.

4. Using the Calculator

Tips: Enter QT interval in milliseconds and heart rate in beats per minute. All values must be valid (QT > 0, HR > 0).

5. Frequently Asked Questions (FAQ)

Q1: What is a normal QTc value?
A: Normal QTc is typically less than 440 ms for men and less than 460 ms for women. Values above 500 ms indicate high risk for arrhythmias.

Q2: Why is QTc correction important?
A: The QT interval naturally shortens with faster heart rates. Correction allows comparison of QT values across different heart rates.

Q3: When should QTc be measured?
A: QTc should be measured in standard ECG leads, preferably lead II or V5, and averaged over multiple beats for accuracy.

Q4: Are there limitations to Bazett's formula?
A: Bazett's formula may overcorrect at high heart rates and undercorrect at low heart rates. Alternative formulas exist for extreme rates.

Q5: What clinical conditions affect QTc?
A: Many medications, electrolyte imbalances, and congenital syndromes can prolong QTc and increase arrhythmia risk.