Which of the following is a correct set of normal interval values?

• A. PR 120-200, HV 35-55, QRS <120, AH 50-120
• B. PR 60-100, HV 20-30, QRS 120-140, AH 25-60
• C. PR 200-240, HV 60-100, QRS <100, AH 10-40
• D. PR 80-100, HV 40-60, QRS <110, AH 70-110

Answer: (A)

Normal interval values in electrophysiology describe how long conduction takes through the main parts of the conduction system. The PR interval on a surface ECG represents atrial conduction plus the AV nodal delay and should be about 120 to 200 milliseconds. The AH interval reflects conduction from the atrium to the His bundle via the AV node and normally ranges from roughly 50 to 120 milliseconds. The HV interval measures conduction from the His bundle to the ventricles, with a typical range of about 35 to 55 milliseconds. The QRS duration represents ventricular depolarization and is normally under 120 milliseconds. The set that lists PR 120-200, AH 50-120, HV 35-55, and QRS <120 aligns with these normal values, making it the best choice. Other sets deviate by having PR or HV values outside the normal ranges, or AH ranges outside the expected window, or a QRS duration that is not within normal limits.