ACLS: Bradycardia

Background

• Only intervene if pt is symptomatic (hypotension, AMS, chest pain, pulm edema)

Categories

1. Sinus node dysfunction
   1. Sinus bradycardia
   2. Sinus arrest
   3. Tachy-brady syndrome (sick sinus)
   4. Chronotropic incompetence
2. AV node dysfunction
   1. 1st degree AV block
   2. 2nd degree AV block Mobitz I/Wenckebach
   3. 2nd degree AV block Mobitz II
   4. 3rd degree AV block (complete heart block)

Differential

1. Ischemia/Infarction
   1. Inferior MI (involving RCA)
2. Neurocardiogenic/reflex-mediated
   1. Increased ICP
   2. Vasovagal reflex
   3. Hypersensitive carotid sinus syndrome
   4. Intra-abdominal hemorrhage (i.e. ruptured ectopic)
3. Metabolic/endocrine/environmental
   1. Hyperkalemia
   2. Hypothermia (Osborn waves on ECG)
   3. Hypothyrodism
4. Toxicologic
   1. Digoxin toxicity
5. Infectious/Postinfectious
   1. Chagas dz
   2. Lyme dz
   3. Syphilis

Treatment

1. Atropine
   1. Can be used as temporizing measure (while awaiting pacing and/or chronotropes)
   2. Use cautiously in pts w/ ongoing ischemia (tachycardia may worsen ischemia)
   3. 0.5mg q3-5min (max 3 mg or 6 doses)
      1. may not work in 2nd/3rd deg HB, heart transplantTranscutaneous pacing
2. Chronotropes
   1. Dopamine 2-10mcg/kg/min
   2. Epinephrine 2-10mcg/min
3. Transcutaneous pacing
   1. Set: HR 80, pacing threshold usually btwn 40-80 mA
      1. Final current set 5-10 mA above threshold level for pt
      2. Look for clear QRS complex and T-wave following pacer spike
      3. Check pulse to confirm mechanical capture
   2. Pad placement:
      1. Pad on apex of heart and other on R upper chest
      2. Pad on lead V3 position and btwn L scapula and T-spine
4. Transvenous pacing
   1. Required if transcutaneous pacing + chronotropes is ineffective
   2. Set: HR 80, max current output (usually 20 mA)
      1. Final current set to twice the threshold level for pt

See Also

• ACLS (Main)
• Bradycardia (Wide)