Which of the following ranges would indicate a prolonged QRS interval when assessing ECGs?

Which of the following ranges would indicate a prolonged QRS interval when assessing ECGs?

• A. 0.04-0.12
• B. 0.08-0.16
• C. 0.20-0.30
• D. 0.14-0.22

Answer: (C)

A QRS duration represents how long ventricular depolarization takes. Normal QRS width is about 0.08 to 0.12 seconds. If it exceeds roughly 0.12 seconds, it’s considered prolonged, indicating some delay in the ventricles’ conduction system (for example, a bundle branch block). The range of 0.20 to 0.30 seconds lies well within the prolonged territory, far above the normal upper limit, so it clearly indicates a prolonged QRS interval. The other ranges either sit at or below the normal threshold or mix normal values with prolonged ones, making them less definitive for labeling the QRS as prolonged.

A QRS duration represents how long ventricular depolarization takes. Normal QRS width is about 0.08 to 0.12 seconds. If it exceeds roughly 0.12 seconds, it’s considered prolonged, indicating some delay in the ventricles’ conduction system (for example, a bundle branch block).

The range of 0.20 to 0.30 seconds lies well within the prolonged territory, far above the normal upper limit, so it clearly indicates a prolonged QRS interval. The other ranges either sit at or below the normal threshold or mix normal values with prolonged ones, making them less definitive for labeling the QRS as prolonged.