QTc Calculation Bazett

Bazett's Formula:

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

Corrected QT Interval (QTc):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Bazett's Formula?

Bazett's formula is the most commonly used method for correcting the QT interval for heart rate. The corrected QT interval (QTc) helps assess ventricular repolarization and identify potential arrhythmia risks.

2. How Does the Calculator Work?

The calculator uses Bazett's formula:

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

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 adjusts the measured QT interval based on the heart rate to provide a standardized value that can be compared across different heart rates.

3. Importance of QTc Calculation

Details: QTc calculation is essential for evaluating cardiac repolarization abnormalities, assessing risk of torsades de pointes, and monitoring drug effects on cardiac conduction.

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

Q2: Why correct QT interval for heart rate?
A: The QT interval naturally shortens with increasing heart rate. Correction allows comparison of QT intervals 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, Hodges) 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, in those with syncope or family history of sudden cardiac death, and in routine ECG interpretation.

Q5: How is the QT interval measured on ECG?
A: The QT interval is measured from the beginning of the QRS complex to the end of the T wave, typically in lead II or V5 where the T wave is most clearly defined.