Corrected QTc Calculator

Bazett's Formula:

\[ QTc = \frac{QT}{\sqrt{RR}} \]

Corrected QTc:

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1. What is the Corrected QTc Calculator?

The Corrected QTc Calculator uses Bazett's formula to adjust the QT interval for heart rate, providing a standardized measure of ventricular repolarization that is independent of heart rate variations.

2. How Does the Calculator Work?

The calculator uses Bazett's formula:

\[ QTc = \frac{QT}{\sqrt{RR}} \]

Where:

\( QT \) — QT interval measured 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 by dividing by the square root of the RR interval, providing a rate-independent measure of ventricular repolarization.

3. Importance of QTc Calculation

Details: Accurate QTc calculation is crucial for assessing cardiac repolarization abnormalities, identifying patients at risk for arrhythmias, and monitoring drug effects on cardiac conduction.

4. Using the Calculator

Tips: Enter QT interval in milliseconds and heart rate in beats per minute. All values must be valid (QT > 0, HR > 0).

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 less than 460 ms for women. Values above these thresholds may indicate prolonged QT syndrome.

Q2: 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.

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 situations.

Q4: When should QTc be measured?
A: QTc should be measured in patients taking medications that affect cardiac repolarization, those with syncope or family history of sudden death, and in routine cardiac assessments.

Q5: How is QT interval measured on ECG?
A: QT interval is measured from the beginning of the QRS complex to the end of the T wave, typically in lead II or V5, using the tangent method for T wave end determination.