Cardiovascular System >
Cardiomyopathy

“A general term for diseases of the heart muscle, where the walls of the heart chambers have become thickened, stiff, or stretched.”

  • Forms of Cardiomyopathy:
    • Hypertrophic Cardiomyopathy (HC)
    • Restrictive Cardiomyopathy (RC)
    • Dilated Cardiomyopathy (DC)
    • Broken Heart Syndrome (Takotsubo Cardiomyopathy, TC)
Risk Factors
  • Uncontrolled high blood pressure
  • Alcohol and recreational drugs
  • Heart valve problem
  • Diseases of the tissues or blood vessels (sarcoidosis, amyloidosis, lupus, polyarteritis nodosa, vasculitis or muscular dystrophy)
Aetiology
  • HC – Autosomal Dominant Genetic Mutation in one of the 12 genes that are important for heart development
  • RC – Usually autosomal dominant inheritance, but autosomal recessive, X-linked and mitochondrial-transmitted disease occurs
  • DC – 50% Familial Dilated Cardiomyopathy (FDCM) – Autosomal Dominant, 50% varied inheritance
  • TC – Not inherited. Excess of the stress hormone adrenaline caused by emotional or physical distress (e.g. bereavement, domestic abuse, physical assault or recent surgery)
Pathophysiology
  • HC:
    1. Mutation in the sarcomere
    2. Instigates a series of proximal defects (e.g. altered ATPase activity)
    3. Molecular changes induce histological and morphological changes  
    4. Myocyte hypertrophy and fibrosis
    5. Reduced ventricular volume
  • RC:
    1. Cardiomyocytes replaced with abnormal scar tissue
    2. ventricular stiffness
    3. Contraction unaffected however filling is ↓
    4. ↓ CO
    5. Reduced ventricular filling causes atria dilation
  • DC:
    1. Primary cardiomyopathic process
    2. ↓ Systolic function caused by myocardial remodelling
    3. ↑ End-systolic / end-diastolic volumes
    4. Progressive dilatation
    5. Significant tricuspid and mitral valve insufficiency
    6. Further lowers the ejection fraction
  • TC – Precise cause is unknown:
    1. Likely, surging stress hormones (esp. adrenaline) “stun” the heart
    2. Triggering changes in cardiomyocytes and coronary blood vessels
    3. Prevent effective LV contraction.
    4. REVERSIBLE
Clinical Presentation
  • HC – Dizziness, Chest pain, SOB, & Syncope
    • The most common cause of sudden unexpected death in childhood and in young athletes
  • RC – Similar to HF – SOB, Oedema, Fatigue, Rhythm problems
  • DC – Similar to HF – SOB, Oedema, Fatigue, Palpitations
  • TC – Similar to a heart attack – Chest pain, SOB, N&V
Investigations
  • Bloods: n/a
  • Imaging:
    • MRI
    • Echocardiogram
  • Special:
    • ECG
    • 24 or 48-hour ECG monitor
    • Exercise test
    • A detailed family tree may be required for the diagnosis of a familial cardiomyopathy
Management
  • There’s usually no cure for cardiomyopathy, but the treatments can be effective at controlling symptoms and preventing complications
  • Most commonly used medications are: ACE inhibitors, angiotensin receptor blockers, beta-blockers and warfarin
Complications
  • Heart failure
  • Heart valve regurgitation
  • Sudden cardiac arrest

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