1. What is QTc Calculation?

The QTc (Corrected QT Interval) calculation adjusts the measured QT interval for heart rate using Bazett's formula. In pediatrics, a QTc value below 440 ms is considered normal, while values ≥440 ms may indicate prolonged QT interval.

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 (seconds)
• \( HR \) — Heart rate (beats per minute)

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

3. Importance of QTc Calculation

Details: Accurate QTc calculation is crucial for detecting long QT syndrome, assessing arrhythmia risk, and monitoring medication effects on cardiac repolarization in pediatric patients.

4. Using the Calculator

Tips: Enter QT interval in milliseconds and heart rate in beats per minute. Both values must be positive numbers. The calculator will automatically compute the RR interval and corrected QT value.

5. Frequently Asked Questions (FAQ)

Q1: Why is QTc important in pediatrics?
A: QTc helps identify congenital long QT syndrome and monitor drug-induced QT prolongation, which can lead to serious arrhythmias in children.

Q2: What is the normal QTc range for children?
A: For pediatrics, normal QTc is generally <440 ms. Values ≥440 ms may indicate prolonged QT interval requiring further evaluation.

Q3: How should QT interval be measured?
A: QT interval should be measured from the beginning of the QRS complex to the end of the T wave, typically in lead II or V5 for consistency.

Q4: Are there limitations to Bazett's formula?
A: Bazett's formula may overcorrect at high heart rates and undercorrect at low heart rates. Other formulas (Fridericia, Hodges) may be used in specific situations.

Q5: When should QTc be monitored?
A: QTc should be monitored when starting QT-prolonging medications, in patients with syncope or family history of sudden death, and in suspected long QT syndrome.