QTc RR Interval Calculator

Bazett's Formula:

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

Corrected QT Interval (QTc):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the QTc RR Interval Calculator?

The QTc RR Interval Calculator uses Bazett's formula to calculate the corrected QT interval (QTc) from the measured QT interval and RR interval. This correction accounts for heart rate variations in electrocardiogram (ECG) analysis.

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 (s)
\( HR \) — Heart rate (bpm)

Explanation: The formula corrects the QT interval for heart rate, providing a standardized measure that can be compared across different heart rates.

3. Importance of QTc Calculation

Details: Accurate QTc calculation is crucial for assessing cardiac repolarization, identifying prolonged QT syndrome, and evaluating drug-induced QT prolongation that may lead to serious arrhythmias.

4. Using the Calculator

Tips: Enter QT interval in milliseconds and RR interval in seconds. Both values must be positive numbers. For accurate results, use precise measurements from a standard 12-lead ECG.

5. Frequently Asked Questions (FAQ)

Q1: Why use Bazett's formula for QTc calculation?
A: Bazett's formula is the most widely used and clinically accepted method for correcting QT interval for heart rate in clinical practice.

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

Q3: How is RR interval related to heart rate?
A: RR interval (in seconds) = 60 / HR, where HR is the heart rate in beats per minute (bpm).

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 like Fridericia's may be used in specific cases.

Q5: When should QTc be measured?
A: QTc should be measured in patients taking medications that may prolong QT interval, in those with syncope or family history of sudden cardiac death, and in routine ECG interpretation.