Final answer:
Volatile anesthetics typically cause QT prolongation on an ECG, reflecting increased time for ventricular depolarization and repolarization, which is important for monitoring the risk of arrhythmias during anesthesia.
Step-by-step explanation:
How volatile anesthetics typically affect the QT interval on an electrocardiogram (ECG) can be variable, but most of the common volatile anesthetics are known to cause QT prolongation. The QT interval represents the total time taken for ventricular depolarization and repolarization, which corresponds to the electrical events from the start of the QRS complex to the end of the T wave on an ECG. It's important to monitor because significant prolongation can be a risk factor for the development of a type of ventricular tachycardia called Torsades de pointes. Therefore, option (a) Prolongation is the typical effect of volatile anesthetics on the QT interval. The effect on the QT interval is crucial for evaluating potential arrythmias and managing patients under general anesthesia.