Sinus Node Dysfunction

Overview

• Sick sinus syndrome (SSS) occurs when the sinus node is not functioning correctly, due to either intrinsic or extrinsic causes.

• • Manifestations of Sinus Node Dysfunction

  • Sinus bradycardia
  • Sinus arrhythmia
  • Sinus pause / arrest
  • Sinoatrial exit block
  • Tachy-brady syndrome

• • Causes of Sinus Node Dysfunction

  • Intrinsic

  • Idiopathic degeneration
  • Myocardial infarction
  • Infiltrative disease - sarcoidosis, amyloidosis, haemochromatosis
  • Connective tissue disease - SLE, scleroderma, RA
  • Cardiac surgery - valvular surgery, correction of congenital heart disease
  • Infections - Lyme disease, endocarditis

  • Extrinsic

  • Physiologic - sleep, athletes
  • Autonomic - neurocardiogenic syncope, carotid sinus hypersensitivity
  • Drugs - beta blockers, calcium channel blockers, digoxin, adenosine, ivabradine, clonidine, acetylcholinesterase inhibitors
  • Hypothyroidism
  • Hypothermia
  • Hyperkalaemia
  • Obstructive sleep apnoea
  • Raised intracranial pressure