Bradycardias: cardiac conduction system disease. Syncope

1. Big picture

This topic connects slow heart rhythms, conduction blocks, and transient loss of consciousness.

The examiner wants you to answer three clinical questions:

1. Is the patient unstable now?
   → hypotension, shock, chest pain, heart failure, syncope → treat immediately.

2. Where is the conduction problem?
   → sinus node, AV node, His-Purkinje system, or reflex/autonomic cause.

3. Does the patient need pacing?
   → temporary pacing for emergency; permanent pacemaker for irreversible symptomatic bradycardia or high-grade AV block.

Bradycardia becomes dangerous when the heart rate is too slow to maintain cerebral and systemic perfusion, causing **pr