heart block or AV nodal block types, causes, and characteristics

1st degree

  • PR > 200 ms
  • no treatment

3rd degree

  • AV dissociation in HIS purkinje
  • sx determined by rate of escape
  • pause dependent VT: torsades de pointe => syncope

2nd degree

  • AV node itself

  • causes:

    • lupus
    • lyme
    • iatrogenic: AV ablation, pacemaker placement

  • Mobitz 1: progressively longer PR, then dropped beat, regularly irregular

    • before/after drop beat, changes in PR the greatest
    • canon A waves, progressively softer 1st heart sound

  • Mobitz 2: HIS purkingje

    • fixed PR
    • dropped beat
    • wide QRS

  • 2:1 weckeback: Mobitz 1 has narrow QRS. Mobitz 2 has wide QRS

  • walk the patient: increase sympathetic tone. Type 1 gets better on atropine. Type 2 does not change

  • Type 2: prophylactic pacing

  • atrial tachycardia can mimic AV block with more p waves than QRS