QT Interval Calculator
Calculate corrected QT interval (QTc) using Bazett, Fridericia, Hodges, and Framingham formulas. Essential tool for ECG interpretation and cardiac risk assessment.
Step 1: ECG Parameters
Understanding QT Interval
The QT interval represents the time from the start of the QRS complex to the end of the T wave on an ECG. It’s crucial for assessing ventricular repolarization and identifying risk of arrhythmias.
Step 2: Calculation Methods
About QTc Formulas
Different formulas adjust QT interval for heart rate. Bazett’s is most common but overcorrects at high heart rates. Fridericia and Hodges are more accurate across a wider range of heart rates.
QTc Calculation Results
Corrected QT Interval (QTc)
QTc Formula Comparison
| Formula | Calculation | QTc Result | Interpretation | Best For |
|---|
Clinical Interpretation
QT Interval Reference Ranges
Normal QTc: < 440 ms (men), < 460 ms (women)
Borderline QTc: 440-460 ms (men), 460-480 ms (women)
Prolonged QTc: > 460 ms (men), > 480 ms (women)
Severely Prolonged: > 500 ms (high risk for Torsades de Pointes)
Clinical Considerations
Causes of QT Prolongation
• Congenital long QT syndrome • Medications (antiarrhythmics, antipsychotics, antibiotics) • Electrolyte abnormalities (hypokalemia, hypomagnesemia, hypocalcemia) • Myocardial ischemia • Bradycardia • Hypothyroidism
Important Medical Disclaimer
This calculator is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.
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