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Overview of Cardiomyopathies and Management

May 7, 2025

Cardiomyopathies Lecture Notes

Introduction

  • Video focuses on cardiomyopathies within clinical medicine.
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Types of Cardiomyopathies

  1. **Dilated Cardiomyopathy (DCM)

    • Pathophysiology: Characterized by dilated ventricles due to decreased contractility leading to reduced ejection fraction (<40%) and systolic heart failure (HFrEF).
    • Causes:
      • Alcohol
      • Beriberi (Thiamine deficiency)
      • Cocaine toxicity
      • Chagas disease (Trypanosoma cruzi)
      • Coxsackie B virus
      • Doxorubicin (chemotherapy)
      • Takotsubo (stress-induced)
      • Peripartum (associated with late pregnancy)
    • Pathological Process: Eccentric hypertrophy (sarcomeres added in series).

  2. **Hypertrophic Cardiomyopathy (HCM)

    • Pathophysiology: Asymmetric septal hypertrophy, causing left ventricular outflow tract obstruction (LVOTO) and impaired filling.
    • Characteristics: Heart failure with preserved ejection fraction (HFpEF).
    • Cause: Genetic mutation (often heavy chain myosin gene).
    • Pathological Process: Concentric hypertrophy (sarcomeres added in parallel).

  3. **Restrictive Cardiomyopathy (RCM)

    • Pathophysiology: Myocardial infiltration leads to rigid ventricles and reduced filling, often affecting the right heart.
    • Causes:
      • Amyloidosis
      • Hemochromatosis
      • Sarcoidosis
    • Characteristics: HFpEF, primary right heart failure, and distinct Kussmaul's sign (paradoxical JVP increase during inspiration).**

Complications and Clinical Manifestations

  1. Dilated Cardiomyopathy

    • Biventricular Failure:
      • Left Heart Failure: Reduced cardiac output, pulmonary edema, paroxysmal nocturnal dyspnea, orthopnea.
      • Right Heart Failure: Increased central venous pressure, jugular venous distention, hepatomegaly, pitting edema, ascites.

  2. Hypertrophic Cardiomyopathy

    • Symptoms: SAD (Syncope, Angina, Dyspnea)
    • Arrhythmias: Risk of VT/VF and sudden cardiac arrest.
    • Murmur: Crescendo-decresecendo systolic murmur, varying with preload/afterload changes.
    • Complications: LVOTO causing syncope, ischemia, and potentially fatal arrhythmias.

  3. Restrictive Cardiomyopathy

    • Symptoms: Primarily right heart failure manifestations.
    • Kussmaul's Sign: Paradoxical JVP increase during inspiration.
    • Infiltrative Process: Rigid myocardium affecting filling, similar to constrictive pericarditis but without pericardial knock.

Diagnosis

  • Echocardiography is crucial:
    • DCM: Enlarged ventricles, reduced contractility.
    • HCM: LVOTO, septal hypertrophy, diastolic dysfunction.
    • RCM: Biatrial enlargement, preserved ejection fraction, diastolic dysfunction.
  • Differential Diagnosis of RCM vs. Constrictive Pericarditis:
    • Kussmaul's sign common in both, but pericardial knock and septal dynamics differ.

Treatment Approaches

  1. Dilated and Restrictive Cardiomyopathy

    • Treat like heart failure with beta-blockers, SGLT2 inhibitors, ACE inhibitors, ARBs, aldosterone antagonists, and diuretics.

  2. Hypertrophic Cardiomyopathy

    • Management: Increase venous return and afterload, decrease contractility.
    • Avoid: Vasodilators, diuretics, excessive exercise.
    • Medications: Beta-blockers, calcium channel blockers.
    • Surgical Options: Myectomy, alcohol septal ablation.
    • Arrhythmia Management: AICD implantation for arrhythmia prevention.

Conclusion: Understanding the pathophysiology, complications, and management strategies for the various types of cardiomyopathies is vital for effective treatment and prevention of adverse outcomes.

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