Enter your QT Interval, Heart Rate, Correction Formula, and Gender — the QTc Calculator returns your Corrected QT Interval, RR Interval, Normal Range, and a Clinical Interpretation for normal, borderline, or prolonged.
Corrected QT Interval (QTc)
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RR Interval
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Clinical Interpretation
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Normal Range for Gender
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The QTc (corrected QT interval) is a measure of the time it takes for the heart's ventricles to repolarize, adjusted for heart rate. It's crucial for assessing the risk of dangerous arrhythmias and sudden cardiac death.
Normal QTc values are typically less than 440 msec for men and less than 460 msec for women. Values above 450 msec (men) or 470 msec (women) may indicate prolonged QT syndrome.
Bazett's formula is most commonly used but may overcorrect at high heart rates. Fridericia's formula is more accurate at extreme heart rates, while Framingham and Hodges formulas may be better for specific populations.
Many medications can prolong QTc including certain antibiotics, antiarrhythmics, antipsychotics, and antidepressants. Always check drug interactions and monitor QTc when prescribing these medications.
QTc monitoring should be done when starting QT-prolonging medications, in patients with cardiac conditions, electrolyte imbalances, or family history of sudden cardiac death.
QTc can be affected by electrolyte imbalances (especially potassium and magnesium), medications, heart disease, age, gender, and genetic conditions like long QT syndrome.
This calculator provides accurate QTc calculations using standard formulas. However, clinical decisions should always involve proper ECG interpretation by qualified healthcare professionals and consideration of the patient's overall clinical context.