Kidney, ECG and body measures
Corrected QT interval (QTc)
Corrected QT interval
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QTc
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About this calculator
Corrects the measured QT interval for heart rate. All four common formulas are shown. Bazett over-corrects at fast heart rates and under-corrects at slow ones; Fridericia is often preferred above 90 bpm.
FormulaRR = 60 ÷ heart rate (seconds). Bazett: QT ÷ √RR. Fridericia: QT ÷ ∛RR. Framingham: QT + 154 × (1 − RR). Hodges: QT + 1.75 × (heart rate − 60).
How to read the result
| Result | Meaning |
|---|---|
| Men: 430 ms or less | Normal (borderline 431 to 450, prolonged above 450) |
| Women: 450 ms or less | Normal (borderline 451 to 470, prolonged above 470) |
| 500 ms or more | Markedly prolonged, high risk of torsades de pointes |
References
- Rautaharju PM, 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. Circulation. 2009;119:e241-e250.
- Goldenberg I, et al. QT interval: how to measure it and what is "normal". J Cardiovasc Electrophysiol. 2006;17:333-336.
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