1. What Is Bazett's Formula?

Bazett's formula is used to calculate the corrected QT interval (QTc), which adjusts the QT interval for heart rate. This correction is essential for accurate assessment of cardiac repolarization.

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 (s)
• \( HR \) — Heart rate (bpm)

Explanation: The formula corrects the QT interval for heart rate, providing a standardized measure of ventricular repolarization.

3. Importance Of QTc Calculation

Details: Accurate QTc calculation is crucial for diagnosing long QT syndrome, assessing arrhythmia risk, and monitoring drug effects on cardiac repolarization.

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

Q2: Why use Bazett's formula specifically?
A: Bazett's formula is widely used and provides a simple correction for heart rate, though it may overcorrect at high heart rates.

Q3: When should QTc be measured?
A: QTc should be measured in patients with suspected arrhythmias, those on QT-prolonging medications, or with family history of sudden cardiac death.

Q4: Are there limitations to Bazett's formula?
A: Yes, it may overcorrect at high heart rates and undercorrect at low heart rates. Alternative formulas like Fridericia's may be used in some cases.

Q5: How is QTc used in clinical practice?
A: QTc is used to assess risk of torsades de pointes, monitor drug safety, and evaluate patients with syncope or palpitations.