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 can be compared across different heart rates.

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: QTc calculation is crucial for assessing cardiac repolarization abnormalities. Prolonged QTc intervals may indicate increased risk of ventricular arrhythmias and sudden cardiac death.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What is a normal QTc value?
A: Normal QTc values are typically <440 ms for men and <460 ms for women. Values above these may indicate prolonged QT syndrome.

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

Q3: 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 like Fridericia may be used in specific cases.

Q4: 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.

Q5: What factors can affect QTc?
A: Medications, electrolyte imbalances, genetic factors, and various medical conditions can prolong or shorten the QTc interval.