Mayo Clinic QTc Calc

Mayo Clinic QTc Calculator:

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

QT (ms):

Heart Rate (HR):

bpm

Gender:

Age:

years

Corrected QT (QTc):

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1. What Is The Mayo Clinic QTc Calculator?

The Mayo Clinic QTc Calculator uses Bazett's formula to correct the QT interval for heart rate, adjusted for rhythm, gender, and age-specific normals. It provides a standardized measure of ventricular repolarization.

2. How Does The Calculator Work?

The calculator uses Bazett's formula:

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

Where:

\( QT \) — QT interval measured from start of Q wave to end of T wave (ms)
\( RR \) — RR interval = 60 / HR (s)
\( HR \) — Heart rate (bpm)

Explanation: The formula accounts for the inverse relationship between heart rate and QT interval, providing a rate-corrected value that can be compared across different heart rates.

3. Importance Of QTc Calculation

Details: Accurate QTc calculation is crucial for assessing cardiac repolarization abnormalities, identifying risk of arrhythmias, and monitoring medication effects that may prolong QT interval.

4. Using The Calculator

Tips: Enter QT interval in milliseconds, heart rate in beats per minute, select gender and enter age. All values must be valid (QT > 0, HR > 0, age between 1-120).

5. Frequently Asked Questions (FAQ)

Q1: Why Use Bazett's Formula For QTc Calculation?
A: Bazett's formula is the most widely used method for QT correction and has been validated in numerous clinical studies, though it may overcorrect at very high heart rates.

Q2: What Are Normal QTc Values?
A: Normal QTc is generally <450 ms for men and <460 ms for women. Values above these thresholds may indicate prolonged QT interval.

Q3: When Should QT Measurement Be Performed?
A: QT interval should be measured during stable sinus rhythm, avoiding periods of arrhythmia or rapid heart rate changes.

Q4: Are There Limitations To Bazett's Formula?
A: The formula may overcorrect at high heart rates and undercorrect at low heart rates. Alternative formulas (Fridericia, Hodges) may be used in specific situations.

Q5: How Does Age And Gender Affect QTc?
A: QTc values tend to be longer in women and may increase slightly with age. The calculator accounts for these demographic factors in its calculations.