What is the normal range for the QT interval?

The normal range for the QT interval is typically considered to be between 0.36 to 0.44 seconds. This measurement reflects the time it takes for the heart's electrical system to reset after each heartbeat, specifically measuring the time from the start of the Q wave to the end of the T wave on an electrocardiogram (ECG).

A QT interval that falls within this range is important for assessing the heart's rhythm and ensuring that it functions properly. A prolonged QT interval can indicate an increased risk of serious arrhythmias, so understanding the normal range helps in the early detection of potential cardiac issues.

The other ranges provided do not represent normal values, as they either fall below or significantly exceed the typical parameters set by clinical guidelines and studies, which highlight the importance of the correct quartile for patient safety and treatment decisions.