Cardiac Channelopathies

  • Blanket term for numerous conditions affecting the cardiac conduction system
    • Conduction speed can be increased or decreased
    • Ion channel mutations
  • Major cause of sudden cardiac death
    • 5-15% of patients have structurally normal hearts
  • Inherited disorders that present with arrhythmia and multi-organ involvement
    • Long QT Syndrome
    • Brugada
    • Polymorphic VT
    • Short QT Syndrome
  • Genes responsible include:
    • KCNQ1
    • KCNH2
    • SCN5A

Long QT Syndrome (LQTS)

Long QT

  • Underdiagnosed disorder
  • Prolongation of cardiac action potentials
    • Predominantly Na and K channel deficiency
      • Timothy Syndrome caused by a Ca channel deficiency

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  • Congenital
  • Heterogeneous
  • Increased risk of
    • Syncope
    • Seizure
    • SCD
    • Arrhythmia
  • Arrhythmia can be triggered by
    • Exertion
    • Stress/emotion

 

Pharmacological triggers:

  • Anti-arrhythmics
    • Class 1a Procainamide and Quinidine
    • Class 3 Soltalol and Amiodarone
  • Non cardiac
    • Cisparide
    • Terfenadine

Multi-organ involvement:

  • Jervell & Lange-Nielsen Syndrome
    • LQTS with congenital deafness
  • Andersen-Tawil Syndrome
    • LQTS with facial dysmorphia and hypokalaemic paralysis
  • Timothy Syndrome
    • LQTS with AV block and developmental disorders

Symptoms

  • Syncope
  • Seizure
  • Sudden death
  • Chest pain/palpitations

Diagnosis

  • Resting 12-Lead ECG
  • Ambulatory ECG monitoring
    • QTc boundaries for male and female criteria
  • Pharamacological Stress testing
    • Usually adrenaline

Heart

 

 

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