1. What is the Framingham Formula?

The Framingham formula is used to correct the QT interval for heart rate, providing the QTc value. This correction is essential for accurate assessment of cardiac repolarization and detection of potential arrhythmia risks.

2. How Does the Calculator Work?

The calculator uses the Framingham formula:

Where:

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

Explanation: The formula adjusts the measured QT interval based on the heart rate to provide a rate-corrected value that can be compared across different heart rates.

3. Importance of QTc Calculation

Details: Accurate QTc calculation is crucial for diagnosing long QT syndrome, assessing arrhythmia risk, and monitoring patients on medications that may prolong QT interval.

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: Why is QTc correction important?
A: QT interval varies with heart rate. Correction allows comparison of QT values across different heart rates and identification of abnormal repolarization.

Q2: What are normal QTc values?
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 QT measurement be performed?
A: QT measurement should be done from ECG tracings with clear definition of Q wave onset and T wave end, preferably averaging multiple beats.

Q4: Are there different QT correction formulas?
A: Yes, besides Framingham, other formulas include Bazett's, Fridericia's, and Hodges formulas, each with different applications and limitations.

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