Sick sinus syndrome

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  • Also known as sinus dysfunction, sinoatrial node disease, and tachycardia-bradycardia syndrome (a specific variant)
  • Collection of signs or symptoms that indicate sinus node dysfunction[1]
  • May present as bradycardia, tachycardia, or alternating bradycardia and tachycardia
    • 50% have alternating bradycardia and tachycardia (i.e. tachycardia-bradycardia syndrome)


Clinical Features

Differential Diagnosis

Narrow-complex tachycardia

Symptomatic bradycardia


  • ECG identification, inpatient telemetry, outpatient Holter monitoring, event monitoring, loop monitoring
    • ECG frequently negative for findings early in disease course


  • Remove extrinsic factors and/or pacemakers
    • Pacemakers do not reduce mortality, only decrease symptoms
  • Consider reversible causes e.g. treat hyperkalemia or hypokalemia
  • Atropine for bradycardia, progress to catecholamine or pacing
  • consider aminophylline, which inhibits suppressive effects of adenosine on the SA node in: [2]
    • Acute inferior MI with 2nd or 3rd degree AV block; 250mv IV bolus
    • Heart transplant: 6mg/kg in 100-200mL of IV fluid over 20-30 minutes
    • Spinal cord injury: 6mg/kg in 100-200mL of IV fluid over 20-30 minutes


  • Admit


See Also

External Links


  1. Semelka, M et Al. Sick Sinus Syndrome: A Review. Am Fam Physician. 2013 May 15;87(10):691-696.
  2. Kusumoto FM, et al. 2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2019 Aug 20;74(7):e51-e156