True or False: An HV interval of 120 ms would be an indication for a pacemaker?

True or False: An HV interval of 120 ms would be an indication for a pacemaker?

• A. True
• B. False
• C. Cannot be determined
• D. Depends on patient

Answer: (A)

The important idea is that the HV interval reflects conduction through the His-Purkinje system. A normal HV interval is about 35–55 ms. An HV interval of 120 ms is markedly prolonged and indicates infra-Hisian (below the AV node) conduction disease. This kind of block is unpredictable and can progress to complete heart block, which can cause dangerous bradycardia or syncope. Pacing is used to prevent such pauses, so a markedly prolonged HV interval is an indication for a pacemaker, especially if the patient has symptoms or there is concern for progression.

The important idea is that the HV interval reflects conduction through the His-Purkinje system. A normal HV interval is about 35–55 ms. An HV interval of 120 ms is markedly prolonged and indicates infra-Hisian (below the AV node) conduction disease. This kind of block is unpredictable and can progress to complete heart block, which can cause dangerous bradycardia or syncope. Pacing is used to prevent such pauses, so a markedly prolonged HV interval is an indication for a pacemaker, especially if the patient has symptoms or there is concern for progression.