I. Decreased automaticity of sinus node results in severe sinus bradycardia, sometimes accompanied by sinoatrial exit block; occasionally even get sinus arrest

II. Occasionally get intermittent SVT (e.g. Afib, Aflutter, PSVT)-"tachy-brady" sd; unclear why this occurs

  1. Sinus arrest most commonly occurs at the end of an episode of SVT, because tachycardia further suppresses sinus node automaticity

III. Often aggravated by increased vagal tone, drugs, etc. (see above for sinus bradycardia)

IV. Usually occurs in elderly

V. Complications

  1. CHF or angina can occur due to brady or tachy episodes
  2. Systemic arterial embolism occurs in 10-20%

VI. Diagnosis by Holter monitoring

VII. Treatment

  1. For bradycardic episodes
  1. In emergency, atropine or epinephrine
  2. For long-term treatment, Permanent Pacemaker (no good long-term drugs)
  1. Complex criteria for permanant pacing which I didn't write down
  1. For tachycardic episodes (see also under SVT's, below)
  1. Dig is good but may decrease sinus node automaticity
  2. Ditto for IA antiarrhythmics
  3. Only use beta-blockers and calcium blockers if pt has pacemaker
  4. When drugs don't work and tachycardia is recurrent and symptomatic, can do His bundle ablation and ventricular pacing
  1. Chronic anticoagulation recommended?