A QRS duration of 125 ms is considered normal.

• A. Yes
• B. No
• C. Borderline
• D. Depends on heart rate

Answer: (B)

A QRS duration measures how long the ventricles take to depolarize. In a healthy heart, ventricular depolarization completes in up to about 120 milliseconds on a standard ECG. A value of 125 milliseconds is slightly longer than normal, indicating a mild intraventricular conduction delay (such as a very early or partial bundle branch delay) or other conduction abnormalities. Because of that, it is not considered normal. The classification isn’t primarily driven by heart rate, though rates can influence other ECG intervals; 125 ms clearly falls outside the normal upper limit. So the correct interpretation is that a 125 ms QRS is prolonged, not normal.