1. What is QT Correction?

QT correction is a method to adjust the measured QT interval for heart rate, providing a standardized QTc value that can be compared across different heart rates. This is important because the QT interval naturally varies with heart rate.

2. How Does the Calculator Work?

The calculator uses four different formulas for QT correction:

Where:

• QT — Measured QT interval in milliseconds
• RR — RR interval in seconds (RR = 60 / HR)
• HR — Heart rate in beats per minute

3. Importance of QTc Calculation

Details: Accurate QTc calculation is crucial for assessing the risk of arrhythmias, particularly torsades de pointes. Prolonged QTc intervals may indicate increased risk and require medical attention.

4. Using the Calculator

Tips: Enter the measured QT interval in milliseconds, heart rate in bpm, and select the desired correction formula. All values must be valid positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Which formula is most accurate?
A: Bazett's formula is most commonly used but tends to overcorrect at high heart rates. Fridericia's formula may be more accurate across a wider range of heart rates.

Q2: 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.

Q3: When should QTc be measured?
A: QTc should be measured in patients taking medications that may prolong QT interval, or when assessing risk of arrhythmias.

Q4: Are there limitations to these formulas?
A: Different formulas may give different results, especially at extreme heart rates. Clinical judgment should always be used.

Q5: Should multiple formulas be compared?
A: In some cases, comparing results from different formulas can provide a more comprehensive assessment, particularly when heart rate is very high or very low.