Final answer:
The QT interval, indicating the time for ventricular depolarization and repolarization, can be measured with regular rhythms, not only with irregular ones. Prolongation can lead to long QT syndrome and is important for diagnosing cardiac conditions.
Step-by-step explanation:
The QT interval on an ECG represents the total time for ventricular depolarization and repolarization. Contrary to some misconceptions, prolongation of the QT interval can indeed occur with regular rhythms and can be measured during them. It is not exclusive to irregular rhythms. Prolongation of the QT interval may lead to a condition called long QT syndrome, which can increase the risk of sudden cardiac events.
The QT interval is crucial for diagnosing various cardiac conditions and for evaluating drug safety, as many medications can cause QT interval prolongation, leading to potential arrhythmias. Therefore, accurate measurement of the QT interval, whether the rhythm is regular or irregular, is an important component of electrocardiogram (ECG) interpretation.