Question

What are some causes of an exit block that may cause failure to capture and undersensing in an implanted pacemaker?

Answer 1

Exit blocks in an implanted pacemaker can be caused by localized ischemia, certain drugs, imbalances in the autonomic nervous system, or disease and pathological conditions.

Step-by-step explanation:

There are several causes of an exit block that may result in failure to capture and undersensing in an implanted pacemaker:

1. Localized ischemia: Reduced blood flow to a specific area of the heart can result in an exit block, preventing the pacemaker from effectively capturing the heart's electrical signals.
2. Certain drugs: Caffeine, digitalis, and acetylcholine can stimulate abnormal electrical activity in the heart, leading to an exit block.
3. An imbalance in the autonomic nervous system: Overstimulation from either the sympathetic or parasympathetic divisions of the autonomic nervous system can interfere with the pacemaker's ability to sense and capture the heart's signals.
4. Disease or pathological conditions: Various medical conditions, such as heart disease or other pathologies, can disrupt the normal conduction of electrical impulses in the heart and cause exit blocks in the pacemaker.