What Is a Normal QT Interval?


Quick Answer

A normal QT interval is between 350 and 440 milliseconds, according to PubMed. A person's QT interval can change, however, based on the state of his physiology and metabolic processes at the time of the ECG.

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Full Answer

The QT interval, as measured by an electrocardiogram, or ECG, indicates the amount of time it takes for a person's heart to contract and refill with blood before the next contraction, says Mayo Clinic. A QT interval that is longer than normal, given a person's age, sex and heart rate, is a prolonged QT interval and may be an indication of Long QT syndrome, a disorder that affects the heart's electrical system.

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