1. What is the Bazett Formula?

The Bazett formula is a widely used method for correcting the QT interval for heart rate. It provides the corrected QT interval (QTc) which allows for comparison of QT values across different heart rates.

2. How Does the Calculator Work?

The calculator uses the Bazett 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 adjusts the measured 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 crucial for assessing cardiac repolarization, identifying prolonged QT syndrome, and evaluating risk of arrhythmias. The normal QTc range is typically 350-440 ms for men and 350-460 ms for women.

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 between 30-300 bpm).

5. Frequently Asked Questions (FAQ)

Q1: What does a QTc of 428 ms indicate?
A: A QTc of 428 ms falls within the normal range (typically 350-440 ms for men, 350-460 ms for women), indicating normal cardiac repolarization.

Q2: Why is QTc correction important?
A: QT interval varies with heart rate. Correction allows comparison across different heart rates and identification of abnormal repolarization.

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

Q5: What factors can affect QTc?
A: Medications, electrolyte imbalances, cardiac conditions, and genetic factors can all affect QTc duration.