Updated: 2/21/2021

Cardiomyopathies

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Snapshot
  • A 16-year-old boy presents to his pediatrician for syncope. In the past few months, he had syncopal episodes when he played football, soccer, and sprinting. His family history includes sudden cardiac death in several relatives. An echocardiogram shows marked hypertrophy and abnormal systolic anterior leaflet motion of the mitral valve. (Hypertrophic cardiomyopathy)
Introduction
  • Clinical definition
    • cardiomyopathies intrinsically affect the myocardium, leading to systolic or diastolic dysfunction
      • these do not include changes in the myocardium secondary to hypertension, coronary artery disease, or valvular disorders
    • types of cardiomyopathies
      • dilated cardiomyopathy (most common)
      • restrictive/infiltrative cardiomyopathy
      • hypertrophic cardiomyopathy (obstructive vs non-obstructive)
 
Cardiomyopathies

Dilated
Restrictive/Infiltrative
Hypertrophic 
Etiology
  • ABCD
    • Alcohol abuse
    • Beriberi (wet) 
    • Coxsackie B viral myocarditis
    • Chronic Cocaine use
    • Chagas disease
    • Doxorubicin toxicity
  • Hemochromatosis
  • Sarcoidosis
  • Titin mutation 
  • Peripartum cardiomyopathy
  • Radiation therapy
  • Loffler endocarditis (with endomyocardial fibrosis and eosinophilic infiltrate)
  • Endocardial fibroelastosis (in children)
  • Amyloidosis
  • Sarcoidosis 
  • Scleroderma
  • Troponin mutation
  • Hemochromatosis
  • Familial (most common)
    • autosomal dominant
    • mutations in sarcomere proteins (β-myosin heavy chain = myosin binding protein C > tropomyosin = troponin I/C - in order of frequency of mutations)
  • Idiopathic
Pathology
  • Systolic dysfunction from ↓ contractility and ↓ ejection fraction
  • Eccentric hypertrophy (sarcomeres added in series)
  • Stiff myocardium causes diastolic dysfunction
  • Preserved left ventricular systolic function
  • Diastolic dysfunction from compliance of left ventricle
  • Septal hypertrophy
  • Majority of cases are obstructive (hypertrophic obstructive cardiomyopathy)
  • Concentric hypertrophy (sarcomeres added in parallel)
Clinical presentation
  • Congestive heart failure
  • S3 sound
  • Systolic murmur
  • Progressive heart failure
  • Sudden cardiac death
  • S4 sound (and others can present with S3)
  • + Kussmaul sign
  • Syncope with activity
  • Sudden cardiac death (especially in young athletes)
  • S4 sound
  • Systolic murmur without radiation
    • ↑ with Valsalva and standing up
    • ↓ with hand grip and squatting
Diagnostic studies
  • Chest radiography
    • ballooning of heart
  • Echocardiogram
    • dilated ventricles and ↓ ejection fraction
  • Electrocardiogram
    • bundle branch block
  • Chest radiography
    • cardiomegaly and pulmonary congestion
  • Echocardiogram
    • thickening of all structures
    • diastolic dysfunction
  • Endomyocardial biopsy
    • the most accurate test for etiology
  • Electrocardiogram
    • may have low voltages
  • Echocardiography   
    • normal ejection fraction
    • hypertrophy
    • mitral regurgitation
    • decreased end systolic volume and end diastolic volume
  • Electrocardiogram
    • left ventricular hypertrophy
  • Histology
    • tangled and disoriented myofibrils
Treatment
  • Angiotensin-converting enzyme inhibitors
  • β-blockers
  • Spironolactone
  • Automatic implantable cardioverter/defibrillator
  • Biventricular pacemaker
  • Treat underlying condition
  • Diuretics
  • Heart transplant
  • Avoid athletic activities
  • β-blockers
  • Non-dihydropyridine calcium channel blockers
  • Implantable cardioverter/defibrillator

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