sinus bradycardia and nodal blockade

  • AV synchrony can account for up to 25% of HR
  • Higher HR = more heart rate response for CO

SA node dysfunction

sinus bradycardia

Other types of sinus node dysfunction

  • sinus arrest, junctional escape rhythm
  • sinus with pauses
  • tachybrady syndrome
  • sinoatrial exit block: failure of impulse to exit SA
  • secondary sinoatrial exit block:
    • failure of p wave to form
    • p to p shortening, followed by drop beat
  • Sx
    • usually asymptomatic, syncope, fatigue, lightheadedness, dyspnea
  • Treatment
    • symptomatic patient: pacemaker
    • atrial based pacing support
    • most patient get RV lead for backup
    • high vagal tone: very dramatic bradycardia with normal HR between episodes
      • sinus slowing before bradycardia
      • nausea, vomiting, diaphoretic
    • SA node dysfunction: lower HR at baseline

AV nodal block

Bradycardia after MI

treatment

Inpatient

Outpatient

  • pacemaker indications
    • symptomatic bradycardia with no reversible cause
    • permanent afib with symptomatic bradycardia
    • alternating BBB
    • 3rd degree block, Mobitz 2, high degree AV block (>1 nonconducted P)
  • treat if EF < 40%
  • biV pacemaker because RV pacing alone = worse EF
  • Pace RV: wide QRS, LBBB
  • if RBBB develops followed by pacing: biV pacemaker
  • < 30%: ICD CRT biV pacing
  • CXR: pacemaker = skinny. atrial = ventricular
  • icd: coil at RV insertion
  • Biv: 3rd lead, RV anterior, LV posterior