In
cardiology, the
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. The QT interval represents electrical depolarization and repolarization of the ventricles. A lengthened QT interval is a marker for the potential of ventricular tachyarrhythmias like
torsades de pointes and a risk factor for sudden death.