1. What is the Amsterdam QT Calculator?

The Amsterdam QT Calculator uses Bazett's formula to calculate the corrected QT interval (QTc) from the measured QT interval and heart rate. This correction is essential for accurate assessment of cardiac repolarization across different heart rates.

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 (s)
• \( HR \) — Heart rate (bpm)

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 diagnosing long QT syndrome, assessing arrhythmia risk, and monitoring drug effects on cardiac repolarization.

4. Using the Calculator

Tips: Enter QT interval in milliseconds and heart rate in beats per minute. Both values must be positive numbers for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal QTc value?
A: Normal QTc values are typically less than 440 ms for men and 460 ms for women. Values above these may indicate prolonged QT syndrome.

Q2: Why is QTc correction important?
A: The QT interval naturally varies with heart rate. Correction allows comparison of QT measurements at different heart rates.

Q3: 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, Framingham) may be used in specific cases.

Q4: When should QT measurement be performed?
A: QT measurement should be done on resting ECGs, avoiding periods of tachycardia or bradycardia when possible.

Q5: What factors can affect QT interval?
A: Medications, electrolyte imbalances, heart disease, and genetic factors can all affect the QT interval duration.