A QRS duration longer than 0.12 seconds is considered prolonged. Which range would indicate a prolonged QRS?

A QRS duration longer than 0.12 seconds is considered prolonged. Which range would indicate a prolonged QRS?

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

Answer: (C)

QRS duration shows how long ventricular depolarization takes. A normal QRS is up to 0.12 seconds (120 ms). If it lasts longer than 0.12 seconds, that’s considered prolonged because it means the ventricles are taking longer than usual to depolarize, often due to delayed conduction like a bundle branch block or other ventricular conduction disturbances. Among the ranges given, the one that is entirely above the 0.12-second threshold is 0.20–0.30 seconds. This range clearly indicates prolongation. The other options either fall within normal limits or include values at or near the threshold, so they don’t definitively indicate a prolonged QRS.

QRS duration shows how long ventricular depolarization takes. A normal QRS is up to 0.12 seconds (120 ms). If it lasts longer than 0.12 seconds, that’s considered prolonged because it means the ventricles are taking longer than usual to depolarize, often due to delayed conduction like a bundle branch block or other ventricular conduction disturbances.

Among the ranges given, the one that is entirely above the 0.12-second threshold is 0.20–0.30 seconds. This range clearly indicates prolongation. The other options either fall within normal limits or include values at or near the threshold, so they don’t definitively indicate a prolonged QRS.