263.2 📚 國考版

263.2.0.1 必背 — Bradycardia Causes

  • Physiologic: athletes, sleep, vagal
  • Drugs: β-blockers, CCB, digoxin, amiodarone, ivabradine
  • Pathologic: SSS, AV block, ischemia, hypothyroid, hypothermia, ↑ ICP, inferior MI

263.2.0.2 必背 — Sick Sinus Syndrome (SSS)

  • Inappropriate sinus bradycardia + sinus pauses + chronotropic incompetence + tachy-brady
  • Elderly degenerative
  • Symptomatic = pacemaker

263.2.0.3 必背 — AV Blocks

Type Features Treatment
1° PR > 200 ms Usually none
Mobitz I Progressive PR → dropped beat (Wenckebach) Atropine; usually benign
Mobitz II Constant PR + dropped beats Pacemaker often (high risk progression)
3° AV dissociation Pacemaker (almost always)

263.2.0.4 必背 — Pacemaker Indications

  • Symptomatic bradycardia (SSS or AV block)
  • 2° Mobitz II
  • 3° AV block (acquired)
  • Carotid sinus hypersensitivity with recurrent syncope
  • Post-MI AV block (persistent)
  • Bifascicular block + syncope (after EP)

263.2.0.5 必背 — Pacemaker Modes

  • VVI: chronic AF (single chamber V)
  • AAI: SSS without AV block
  • DDD: sinus rhythm + AV block (most common)
  • DDDR: rate-responsive
  • CRT (biventricular): HFrEF + LBBB + symptomatic

263.2.0.6 必背 — CRT Indications

  • HFrEF + EF ≀ 35%
  • LBBB + QRS > 130 ms
  • NYHA II-III on optimal medical therapy
  • Improves mortality + symptoms

263.2.0.7 必背 — 2024 Innovations

  • Leadless pacemakers (Micra, Aveir): no leads
  • His bundle pacing + Left bundle branch area pacing: more physiologic
  • MRI-conditional pacemakers: 1.5T / 3T compatible

263.2.0.8 必背 — Modes Choice

  • Chronic AF: VVI
  • Sinus + AV block: DDD
  • SSS without AV block: AAI
  • HFrEF + LBBB: CRT (biventricular)

263.2.0.9 必背 — Mobitz I vs II

  • Mobitz I (Wenckebach): progressive PR; atropine works; benign typically; AV node block
  • Mobitz II: constant PR + dropped beats; atropine doesn’t help; high progression risk; pacemaker often