1. What is Bazett's Formula?

Bazett's formula is used to calculate the corrected QT interval (QTc) from the measured QT interval and heart rate. It accounts for the fact that the QT interval normally shortens with increasing heart rate.

2. How Does the Calculator Work?

The calculator uses Bazett's 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)

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

3. Importance of QTc Calculation

Details: QTc calculation is crucial for assessing cardiac repolarization and identifying potential arrhythmia risks. Prolonged QTc intervals may indicate increased risk of life-threatening ventricular arrhythmias.

4. Using the Calculator

Tips: Enter QT interval in milliseconds, heart rate in beats per minute, and select gender. Normal ranges: 350-440 ms for men, 350-460 ms for women.

5. Frequently Asked Questions (FAQ)

Q1: Why is QTc correction important?
A: QTc correction allows for comparison of QT intervals across different heart rates, helping to identify abnormal cardiac repolarization.

Q2: What are normal QTc values?
A: Normal QTc ranges are 350-440 ms for men and 350-460 ms for women. Values outside this range may require further evaluation.

Q3: When should QTc be measured?
A: QTc should be measured during routine ECG interpretation, especially when assessing patients for arrhythmia risk or monitoring QT-prolonging medications.

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 situations.

Q5: What causes prolonged QTc?
A: Prolonged QTc can be caused by medications, electrolyte imbalances, congenital long QT syndrome, and various cardiac conditions.