QTc Calculator
About QTc
The QTc (corrected QT) interval is a measure of the time between the start of the Q wave and the end of the T wave in the heart's electrical cycle, corrected for heart rate.
Formula:
This calculator uses Bazett's formula: QTc = QT / √RR
Where QT is measured in milliseconds and RR is measured in seconds.
Interpretation:
- Normal QTc: <450 ms for men, <460 ms for women
- Borderline QTc: 450-470 ms for men, 460-480 ms for women
- Prolonged QTc: >470 ms for men, >480 ms for women
Clinical Significance:
A prolonged QTc interval can indicate an increased risk of arrhythmias and sudden cardiac death. It's important in drug safety evaluations and monitoring certain cardiac conditions.
References:
- Bazett HC. An analysis of the time-relations of electrocardiograms. Heart. 1920;7:353-370.
- Rautaharju PM, Surawicz B, Gettes LS, et al. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part IV: the ST segment, T and U waves, and the QT interval: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Circulation. 2009;119(10):e241-e250.