Mayo QTc Calculator

Mayo QTc Equation:

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

QT (ms):

Heart Rate (HR):

bpm

Gender:

Age:

years

Wide QRS:

Rhythm:

Corrected QT Interval (QTc):

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1. What is the Mayo QTc Calculator?

The Mayo QTc Calculator uses Bazett's formula to correct the QT interval for heart rate, with additional adjustments for rhythm, gender, age, and wide QRS complex. It provides a more accurate assessment of ventricular repolarization.

2. How Does the Calculator Work?

The calculator uses the Bazett's formula with Mayo Clinic adjustments:

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

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)

Additional Adjustments: The Mayo Clinic calculator applies specific adjustments based on rhythm regularity, patient gender, age, and presence of wide QRS complex.

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 bpm, select gender, enter age, and specify wide QRS and rhythm status. All values must be valid (QT > 0, HR > 0, age between 1-120).

5. Frequently Asked Questions (FAQ)

Q1: Why use Bazett's formula with adjustments?
A: While Bazett's formula is widely used, Mayo Clinic adjustments provide more accurate corrections for specific patient populations and conditions.

Q2: What are normal QTc values?
A: Normal QTc is generally <450 ms for men and <460 ms for women. Values above these may indicate prolonged QT syndrome.

Q3: When should QTc be measured?
A: QTc should be measured in standard ECG leads, preferably lead II or V5, and averaged over multiple beats in irregular rhythms.

Q4: Are there limitations to this calculation?
A: Bazett's formula may overcorrect at high heart rates and undercorrect at low heart rates. Clinical judgment should always accompany calculated values.

Q5: Why adjust for wide QRS?
A: Wide QRS complexes can artificially prolong the QT interval, requiring specific correction factors for accurate assessment.