Corrected QTc Calculator Paediatric

Bazett's Formula:

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

Corrected QTc:

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Bazett's Formula?

Bazett's formula is used to calculate the heart rate-corrected QT interval (QTc) from the measured QT interval and heart rate. It's particularly important in paediatric cardiology to 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 corrects the QT interval for heart rate, allowing comparison of QT values across different heart rates.

3. Importance of QTc Calculation

Details: Accurate QTc calculation is crucial for identifying prolonged QT syndrome, assessing arrhythmia risk, monitoring medication effects, and evaluating cardiac safety in children.

4. Using the Calculator

Tips: Enter QT interval in milliseconds and heart rate in beats per minute. Both values must be positive numbers. Normal QTc in children is typically less than 440 ms.

5. Frequently Asked Questions (FAQ)

Q1: Why is QTc important in paediatrics?
A: QTc helps identify congenital long QT syndrome and monitor drug effects that may prolong QT interval, both important for preventing potentially fatal arrhythmias in children.

Q2: What are normal QTc values in children?
A: Normal QTc is typically less than 440 ms in children. Values between 440-460 ms are borderline, and above 460 ms are considered prolonged.

Q3: How should QT interval be measured?
A: QT interval should be measured from the beginning of the QRS complex to the end of the T wave, preferably in lead II or V5, averaging several beats.

Q4: Are there limitations to Bazett's formula?
A: Yes, Bazett's formula tends to overcorrect at high heart rates and undercorrect at low heart rates. Other formulas (Fridericia, Hodges) may be used in specific situations.

Q5: When should I be concerned about a prolonged QTc?
A: Consult a cardiologist if QTc is consistently >440 ms in children, especially if accompanied by symptoms like syncope, seizures, or family history of sudden cardiac death.