Home
Back
Mayo QT Calculator Formula:
| From: | To: |
The Mayo QT Calculator uses Bazett's formula to calculate the corrected QT interval (QTc) from the measured QT interval and heart rate. It provides adjustment for rhythm, gender, and age-specific normals to assess cardiac repolarization.
The calculator uses Bazett's formula:
Where:
Explanation: The formula corrects the QT interval for heart rate, providing a standardized measure that accounts for variations in cardiac cycle length.
Details: Accurate QTc calculation is crucial for assessing cardiac repolarization abnormalities, identifying risk of arrhythmias, and monitoring medication effects on cardiac conduction.
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).
Q1: Why use Bazett's formula for QTc calculation?
A: Bazett's formula is the most widely used method for heart rate correction of QT interval and has been validated in numerous clinical studies.
Q2: What are normal QTc values?
A: Normal QTc values are typically <440 ms for men and <460 ms for women. Values above these may indicate prolonged QT syndrome.
Q3: When should QT interval be measured?
A: QT interval should be measured during electrocardiogram (ECG) assessment, preferably in lead II or V5 where T waves are most prominent.
Q4: Are there limitations to Bazett's formula?
A: The 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: Why are gender and age adjustments important?
A: Women typically have longer QT intervals than men, and QT duration may change with age. These adjustments provide more accurate risk assessment.