1. What is QTc Calculation?

The QTc (corrected QT interval) calculation adjusts the QT interval for heart rate using Bazett's formula. This provides a standardized measure of ventricular repolarization that can be compared across different heart rates.

2. How Does the Calculator Work?

The calculator uses Bazett's formula:

Where:

• \( QT \) — QT interval measured from start of Q wave to end of T wave (ms)
• \( RR \) — RR interval calculated as 60 / HR (seconds)
• \( HR \) — Heart rate (beats per minute)

Explanation: The formula corrects the QT interval for heart rate, with normal values being <440 ms for men and <460 ms for women.

3. Importance of QTc Calculation

Details: QTc calculation is crucial for assessing cardiac repolarization abnormalities. Prolonged QTc may indicate increased risk of ventricular arrhythmias and sudden cardiac death.

4. Using the Calculator

Tips: Enter QT interval in milliseconds, heart rate in beats per minute, and select gender. All values must be valid positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why correct QT for heart rate?
A: The QT interval naturally shortens with increasing heart rate. Correction allows comparison across different heart rates.

Q2: What are normal QTc values?
A: Normal QTc is <440 ms for men and <460 ms for women. Values above these thresholds may indicate prolonged QT.

Q3: How is QT interval measured?
A: QT is measured from the beginning of the QRS complex to the end of the T wave on an ECG, typically in lead II or V5.

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, Framingham) may be used in specific situations.

Q5: When should QTc be measured?
A: QTc should be assessed in patients with syncope, family history of sudden death, or when prescribing medications known to prolong QT interval.