1. What is the Bazett Formula?

The Bazett formula is a mathematical equation used to correct the QT interval for heart rate, providing the QTc (corrected QT interval). It is commonly used in electrocardiography to assess ventricular repolarization.

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 = 60 / HR (seconds)
• \( HR \) — Heart rate (beats per minute)

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

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 generally <440 ms for men and <460 ms for women. Values above these may indicate prolonged QT syndrome.

Q2: Why is QTc important?
A: Prolonged QTc interval is associated with increased risk of life-threatening ventricular arrhythmias, particularly torsades de pointes.

Q3: When should QTc be measured?
A: QTc should be measured in patients taking medications that affect cardiac repolarization, in those with syncope or family history of sudden cardiac death, and in routine ECG interpretation.

Q4: Are there limitations to the Bazett formula?
A: The Bazett formula may overcorrect at high heart rates and undercorrect at low heart rates. Other formulas (Fridericia, Framingham) may be used in specific situations.

Q5: What factors can affect QTc measurement?
A: Electrolyte imbalances, medications, myocardial ischemia, and autonomic nervous system activity can all affect QTc interval duration.