EKG
Bradycardias & sinus node disease
EKG

Bradycardias & sinus node disease

Sinus brady, sick sinus, junctional rhythms — when to pace.

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◆Sinus bradycardia

  • •Sinus rate < 60 bpm — often normal in athletes
  • •Pathologic causes: medications (β-blocker, CCB, digoxin, opioids, clonidine), inferior MI, hypothyroid, hypothermia, ↑ICP, sleep apnea
  • •Symptomatic → atropine; if refractory → pacing

◆Sick sinus syndrome

  • •Alternating bradycardia and tachycardia (often AFib alternating with sinus brady) — 'tachy-brady'
  • •Common in elderly; causes syncope and palpitations
  • •Diagnosis with Holter or event monitor
  • •Treat: PACEMAKER (then medication can be used to control tachy component safely)

◆Junctional rhythms

  • •Origin: AV node escape — rate 40–60 bpm, narrow QRS, no P or inverted P (retrograde)
  • •Accelerated junctional: 60–100 (digoxin toxicity, post-cardiac surgery, MI)
  • •Treat underlying cause; pacing if symptomatic and persistent

High-yield pearls

  • ◆Symptomatic sinus brady → atropine 0.5 mg IV first; max 3 mg before moving to pacing
  • ◆β-blocker / CCB overdose with bradycardia → calcium gluconate, glucagon, high-dose insulin / euglycemia therapy
  • ◆Sick sinus with concurrent AFib + bradycardia: pacemaker first, then anticoagulate based on CHA₂DS₂-VASc
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