Internal Diseases · MU Sofia

Theory · 17. Cardiomyopathy

Covers the three main forms of cardiomyopathy: dilated, restrictive and hypertrophic. For each, the note moves through definition, causes and pathogenesis, symptoms, physical examination signs, laboratory tests and instrumental findings, including ECG, chest X-ray and echocardiography. It names specific underlying diseases and toxic agents linked to each form, and contrasts the murmur of obstructive hypertrophic cardiomyopathy with that of aortic stenosis.

Inside: 9 sections · 8 labelled pictures · 14 flashcards · 5 min

Topic 16 of 88 in the MU Sofia syllabus for Internal Diseases (Dental Medicine, Year 4). The free AceMed note covers it in 9 sections, about 688 words (5 min of reading), with 14 flashcards.

In this note

  1. Cardiomyopathy
  2. Dilative Cardiomyopathy (DCM)
  3. Restrictive Cardiomyopathy (RCM)
  4. Hypertrophic Cardiomyopathy (HCM)
  5. Etiology and Pathogenesis:
  6. Symptoms:
  7. Physical Examination:
  8. Lab Tests:
  9. Instrumental Tests:

Cardiomyopathy

Definition:

Chronic disease of the myocardium, which deteriorates its function and causes total heart failure (HF).

Classification:

  • Dilative cardiomyopathy
  • Restrictive cardiomyopathy
  • Hypertrophic cardiomyopathy

Dilative Cardiomyopathy (DCM)

Definition:

A condition in which the heart becomes enlarged (dilated) and cannot pump blood effectively. It is the most common type of cardiomyopathy.

Etiology and Pathogenesis:

  • Many cases are idiopathic.
  • Ischemic cardiomyopathy: due to atherosclerosis of coronary arteries → impaired oxygen supply → myocardial damage.
  • Post-myocarditis: often viral (e.g., Coxsackie B and other enteroviruses).
  • Toxic agents: alcohol abuse, drugs (e.g., cocaine), cobalt intoxication, certain chemotherapy agents (e.g., doxorubicin).
  • Metabolic/endocrine: hyperthyroidism.
  • Pregnancy-related: peripartum cardiomyopathy.
  • Other contributing factors:
  • Autoimmune, toxic, and genetic mechanisms lead to impaired myocyte function.
  • This results in dilation of all heart chambers and total heart failure.
  • More common in males.

Symptoms:

  • Total heart failure symptoms:
  • Shortness of breath (SOB), fatigue, weakness, peripheral edema.
  • Palpitations, tachyarrhythmias, risk of sudden death from ventricular fibrillation.
  • Thrombogenesis due to atrial and ventricular dilation → systemic or pulmonary embolism (brain, limbs, kidneys, spleen).

Physical Examination:

  • Poor general condition, possible orthopnea, peripheral cyanosis, leg edema, elevated jugular venous pressure, enlarged tender liver.
  • Lungs:
  • Decreased breath sounds, crepitations (due to congestion), pleural effusion signs (dull percussion, high diaphragm, absent breath sounds in effusion area).
  • Heart:
  • Enlarged cardiac dullness, apex beat displaced (often 5th/6th ICS lateral to MCL).
  • Tachycardia, 3rd heart sound, gallop rhythm.
  • Systolic murmur due to functional mitral/tricuspid regurgitation.
  • Low blood pressure.

Lab Tests:

Directed at identifying the underlying cause (e.g., viral serology, autoimmune markers, thyroid function tests).

Instrumental Tests:

  • ECG:
  • Tachycardia, tachyarrhythmias, ventricular/supraventricular extrasystoles.
  • Diffuse repolarization abnormalities (e.g., flat or inverted T waves), low voltage QRS.
  • Chest X-ray:
  • Cardiomegaly, pulmonary congestion.
  • Echocardiography:
  • Dilated atria and ventricles, diffuse hypokinesia, ↓ EF, relative valve regurgitation.
  • Catheterization/MRI: sometimes necessary for diagnosis or to exclude ischemic disease.

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