1. What is QTc Correction?

QTc (corrected QT interval) is a heart rate-adjusted QT interval that allows comparison of QT values across different heart rates. It's essential for assessing cardiac repolarization and detecting potential arrhythmia risks.

2. How Does the Calculator Work?

The calculator uses multiple correction formulas:

Where:

• \( QT \) — QT interval in milliseconds (ms)
• \( RR \) — RR interval in seconds (s) = 60 / HR
• \( HR \) — Heart rate in beats per minute (bpm)

Explanation: Different formulas provide varying degrees of accuracy across different heart rate ranges and patient populations.

3. Importance of QTc Calculation

Details: Accurate QTc calculation is crucial for detecting prolonged QT syndrome, assessing drug-induced QT prolongation, and evaluating cardiac safety in clinical practice and research.

4. Using the Calculator

Tips: Enter QT interval in milliseconds, heart rate in bpm, and select the desired correction formula. All values must be valid (QT > 0, HR > 0).

5. Frequently Asked Questions (FAQ)

Q1: Which formula is most accurate?
A: Bazett is most commonly used but tends to overcorrect at high heart rates. Fridericia and Framingham are often more accurate across wider heart rate ranges.

Q2: What are normal QTc values?
A: Normal QTc is typically <440 ms for men and <460 ms for women. Values >500 ms are associated with increased arrhythmia risk.

Q3: When should I use different formulas?
A: Bazett is standard for clinical use. Fridericia is preferred in research settings. Framingham and Hodges may be better for extreme heart rates.

Q4: How is QT interval measured?
A: QT is measured from the start of the Q wave to the end of the T wave on ECG, preferably in lead II or V5.

Q5: What causes prolonged QTc?
A: Medications, electrolyte imbalances, congenital syndromes, myocardial ischemia, and neurological disorders can prolong QTc.