1. What is the Bazett Formula?

The Bazett formula is a standard method for correcting the QT interval for heart rate, providing the QTc (corrected QT) value. It helps in assessing the risk of arrhythmias by normalizing QT duration across different heart rates.

2. How Does the Calculator Work?

The calculator uses the Bazett formula:

Where:

• \( QT \) — Measured QT interval from start of Q wave to end of T wave (ms)
• \( RR \) — RR interval = 60 / HR (seconds)
• \( HR \) — Heart rate (beats per minute, bpm)

Explanation: The formula adjusts the QT interval based on the square root of the RR interval to account for heart rate variations.

3. Importance of QTc Calculation

Details: Accurate QTc calculation is essential for diagnosing long QT syndrome, assessing arrhythmia risk, and monitoring drug effects on cardiac repolarization. A QTc >450 ms in men or >470 ms in women is considered prolonged.

4. Using the Calculator

Tips: Enter QT interval in milliseconds and heart rate in beats per minute. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why is QTc correction important?
A: The QT interval varies with heart rate. Correction allows comparison across different heart rates and identification of abnormal repolarization.

Q2: What are normal QTc values?
A: Normal QTc is typically <450 ms for men and <470 ms for women. Values above these thresholds may indicate prolonged QT syndrome.

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 (Fridericia, Hodges) may be used in specific cases.

Q5: What clinical conditions affect QTc?
A: Many factors can prolong QTc including medications, electrolyte imbalances, congenital long QT syndrome, and myocardial ischemia.