Fridericia Formula Calculator

The Fridericia formula is used to correct the QT interval for heart rate. QT interval prolongation can indicate a risk for arrhythmias, so accurately correcting for heart rate is crucial in clinical settings.

Background

The QT interval on an electrocardiogram (ECG) measures the time for the heart’s electrical system to depolarize and repolarize. Since heart rate affects the QT interval, formulas like Fridericia's correct it to a heart-rate-independent value.

Fridericia Formula

The formula is:
\[ QTc = \frac{QT}{\sqrt[3]{RR}} \]
Where:

• QT: The QT interval in milliseconds.
• RR: The RR interval derived from heart rate (RR = 60/heart rate).

Example Calculation

If the QT interval is 400 ms and the heart rate is 75 bpm:
\[ QTc = \frac{400}{\sqrt[3]{75/60}} \approx 384.22 \text{ ms} \]

Usage

The Fridericia formula is commonly used in cardiology for clinical assessments and research studies where accurate QT correction is necessary.

FAQs

1. What is the QT interval?

   • The QT interval is the time taken for ventricular depolarization and repolarization, as seen on an ECG.

2. Why is QT correction important?

   • Correcting QT for heart rate helps assess the risk of arrhythmias more accurately.

3. When should the Fridericia formula be used?

   • It is often preferred when heart rates are outside the normal range or when Bazett’s formula (another correction method) is less reliable.

This calculator provides a quick and accurate way to determine QTc using the Fridericia formula.