QTc Calculation Bazett Range

Bazett's Formula:

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

Corrected QT Interval (QTc):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is QTc Calculation?

The QTc (Corrected QT Interval) calculation using Bazett's formula adjusts the QT interval for heart rate, providing a standardized measure of ventricular repolarization. Normal range: 350-440 ms for adults; prolonged if >440 ms in men, >460 ms in women.

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 (seconds)
\( HR \) — Heart rate (beats per minute)

Explanation: The formula corrects the QT interval for heart rate variations, allowing comparison across different heart rates.

3. Importance of QTc Calculation

Details: Accurate QTc calculation is crucial for assessing risk of arrhythmias, monitoring drug effects, and evaluating cardiac repolarization abnormalities. Prolonged QTc intervals are associated with increased risk of torsades de pointes and sudden cardiac death.

4. Using the Calculator

Tips: Enter QT interval in milliseconds and heart rate in beats per minute. Both values must be positive numbers. The calculator will compute the corrected QT interval using Bazett's formula.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal QTc range?
A: Normal QTc range is 350-440 ms for adults. Values >440 ms in men and >460 ms in women are considered prolonged.

Q2: Why is QTc correction important?
A: QT interval varies with heart rate. Correction allows comparison of QT measurements across different heart rates and patients.

Q3: What are the limitations of 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 more accurate in certain populations.

Q4: When should QTc be measured?
A: QTc should be measured in patients taking medications that affect cardiac repolarization, those with electrolyte imbalances, or when evaluating syncope and arrhythmias.

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. The longest QT interval across multiple leads should be used.