What is a normal HBE interval?

What is a normal HBE interval?

• A. <10 ms
• B. <20 ms
• C. <30 ms
• D. <40 ms

Answer: (C)

The HBE interval gauges how quickly the ventricle begins to activate after the His bundle region depolarizes. In a healthy His–Purkinje system, this activation happens very rapidly, so the interval is short. The usual upper limit for normal is about 30 milliseconds, so values under 30 ms are considered normal. If the interval lengthens beyond this (for example toward 40 ms or more), it suggests delay distal to the His bundle, indicating possible conduction disease in the His–Purkinje system. Therefore, the best choice is the one indicating a value under 30 ms.

The HBE interval gauges how quickly the ventricle begins to activate after the His bundle region depolarizes. In a healthy His–Purkinje system, this activation happens very rapidly, so the interval is short. The usual upper limit for normal is about 30 milliseconds, so values under 30 ms are considered normal. If the interval lengthens beyond this (for example toward 40 ms or more), it suggests delay distal to the His bundle, indicating possible conduction disease in the His–Purkinje system. Therefore, the best choice is the one indicating a value under 30 ms.