1. What is the Fridericia Formula?

The Fridericia formula is a method for correcting 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 Fridericia formula:

Where:

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

Explanation: The formula accounts for the non-linear relationship between QT interval and heart rate, using a cube root correction.

3. Importance of QTc Calculation

Details: Accurate QTc calculation is crucial for assessing risk of arrhythmias, monitoring drug effects on cardiac repolarization, and evaluating patients with potential long QT syndrome.

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: Why use Fridericia formula instead of Bazett?
A: The Fridericia formula provides more accurate correction at extreme heart rates and is less likely to overcorrect at high heart rates compared to Bazett's formula.

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 interval.

Q3: When should QTc be measured?
A: QTc should be measured in standard ECG recordings, preferably averaging multiple beats for accuracy, especially in patients taking medications that affect QT interval.

Q4: Are there limitations to this formula?
A: Like all QT correction formulas, Fridericia may have limitations in certain populations or with very abnormal heart rhythms.

Q5: Should QTc monitoring be routine?
A: QTc monitoring is recommended for patients taking medications known to prolong QT interval or those with risk factors for arrhythmias.