1. What is the Fridericia Formula?

The Fridericia formula is a method for correcting the QT interval for heart rate. It is recommended for better accuracy across different heart rates compared to other formulas like Bazett's.

2. How Does the Calculator Work?

The calculator uses the Fridericia formula:

Where:

• \( QT \) — QT interval measured from start of Q wave to end of T wave (ms)
• \( RR \) — RR interval calculated as 60 / HR (s)
• \( HR \) — Heart rate (bpm)

Explanation: The formula accounts for the non-linear relationship between QT interval and heart rate, providing more accurate correction across various 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. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why use Fridericia formula instead of Bazett's?
A: Fridericia formula provides better accuracy across a wider range of heart rates and is less likely to overcorrect at high heart rates.

Q2: What are normal QTc values?
A: Normal QTc is generally <440 ms for men and <460 ms for women. Values above these may indicate prolonged QT syndrome.

Q3: When should QT measurement be performed?
A: QT measurement should be done on resting ECGs, avoiding periods of tachycardia or bradycardia when possible.

Q4: Are there limitations to this formula?
A: While more accurate than Bazett's, Fridericia may still have limitations at extreme heart rates and in certain patient populations.

Q5: Should automated ECG measurements be trusted?
A: Automated measurements should be verified by manual measurement, especially when values are borderline or clinical suspicion is high.