Chapter 117: Cardiomyopathies and Myocarditis

Chapter 117: Cardiomyopathies and Myocarditis is a topic covered in the Harrison's Manual of Medicine.

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Cardiomyopathies are primary diseases of heart muscle. Table 117-1 summarizes distinguishing presenting features of the three major types of cardiomyopathy (CMP). Table 117-2 details the comprehensive initial evaluation of suspected cardiomyopathies.

TABLE 117-1: Presentation with Symptomatic Cardiomyopathy
 DILATEDRESTRICTIVEHYPERTROPHIC
Ejection fraction (normal >55%)Usually <30% when symptoms severe25–50%>60%
Left ventricular diastolic dimension (normal <55 mm)≥60 mm<60 mm (may be decreased)Often decreased
Left ventricular wall thicknessNormal or decreasedNormal or increasedMarkedly increased
Atrial sizeIncreasedIncreased; may be massiveIncreased
Valvular regurgitationRelated to annular dilationRelated to endocardial involvement; frequent mitral and tricuspid regurgitation, rarely severeRelated to valve-septum interaction: mitral regurgitation
Common first symptomsExertional intoleranceExertional intolerance, fluid retention earlyExertional intolerance; may have chest pain
Congestive symptomsaLeft before right, except right prominent in young adultsRight often dominatesLeft-sided congestion may develop late
ArrhythmiaVentricular tachyarrhythmia; conduction block in Chagas’ disease, and some familial forms. Atrial fibrillationVentricular uncommon except in sarcoidosis, conduction block in sarcoidosis and amyloidosis. Atrial fibrillationVentricular tachyarrhythmias; atrial fibrillation
aLeft-sided symptoms of pulmonary congestion: dyspnea on exertion, orthopnea, paroxysmal nocturnal dyspnea. Right-sided symptoms of systemic venous congestion: hepatic and abdominal distention, discomfort on bending, peripheral edema.
TABLE 117-2: Initial Evaluation of Cardiomyopathy
Clinical Evaluation

Thorough history and physical examination to identify cardiac and noncardiac disordersa

Detailed family history of heart failure, cardiomyopathy, skeletal myopathy, conduction disorders and tachyarrhythmias, sudden death

History of alcohol, illicit drugs, chemotherapy, or radiation therapya

Assessment of ability to perform routine and desired activitiesa

Assessment of volume status, orthostatic blood pressure, body mass indexa

Laboratory Evaluation
Electrocardiograma

Chest radiographa

Two-dimensional and Doppler echocardiograma

Magnetic resonance imaging to assess myocardial inflammation and fibrosis

Chemistry:

 Serum sodium,a potassium,a calcium,a magnesiuma

 Fasting glucose (glycohemoglobin in diabetes mellitus)

 Creatinine,a blood urea nitrogena

 Albumin,a total protein,a liver function testsa

 Lipid profile

 Thyroid-stimulating hormonea

 Serum iron, transferrin saturation

 Urinalysis

 Creatine kinase isoforms

 Cardiac troponin

Hematology:

 Hemoglobin/hematocrita

 White blood cell count with differential,a including eosinophils

 Erythrocyte sedimentation rate

Initial Evaluation When Specific Diagnoses Are Suspected

DNA sequencing for genetic disease; panel selection based on phenotype

Titers for infection in presence of clinical suspicion:

 Acute viral (e.g., coxsackievirus, echovirus, influenza)

 Human immunodeficiency virus

 Chagas’ disease, Lyme disease, toxoplasmosis

Coronary angiography in pts with angina who are candidates for interventiona

Serologies for active rheumatologic disease

Endomyocardial biopsy including sample for electron microscopy when suspecting specific diagnosis with therapeutic implications

Screening for sleep-disordered breathing

aLevel I Recommendations from ACC/AHA Practice Guidelines for Chronic Heart Failure in the adult.

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Cardiomyopathies are primary diseases of heart muscle. Table 117-1 summarizes distinguishing presenting features of the three major types of cardiomyopathy (CMP). Table 117-2 details the comprehensive initial evaluation of suspected cardiomyopathies.

TABLE 117-1: Presentation with Symptomatic Cardiomyopathy
 DILATEDRESTRICTIVEHYPERTROPHIC
Ejection fraction (normal >55%)Usually <30% when symptoms severe25–50%>60%
Left ventricular diastolic dimension (normal <55 mm)≥60 mm<60 mm (may be decreased)Often decreased
Left ventricular wall thicknessNormal or decreasedNormal or increasedMarkedly increased
Atrial sizeIncreasedIncreased; may be massiveIncreased
Valvular regurgitationRelated to annular dilationRelated to endocardial involvement; frequent mitral and tricuspid regurgitation, rarely severeRelated to valve-septum interaction: mitral regurgitation
Common first symptomsExertional intoleranceExertional intolerance, fluid retention earlyExertional intolerance; may have chest pain
Congestive symptomsaLeft before right, except right prominent in young adultsRight often dominatesLeft-sided congestion may develop late
ArrhythmiaVentricular tachyarrhythmia; conduction block in Chagas’ disease, and some familial forms. Atrial fibrillationVentricular uncommon except in sarcoidosis, conduction block in sarcoidosis and amyloidosis. Atrial fibrillationVentricular tachyarrhythmias; atrial fibrillation
aLeft-sided symptoms of pulmonary congestion: dyspnea on exertion, orthopnea, paroxysmal nocturnal dyspnea. Right-sided symptoms of systemic venous congestion: hepatic and abdominal distention, discomfort on bending, peripheral edema.
TABLE 117-2: Initial Evaluation of Cardiomyopathy
Clinical Evaluation

Thorough history and physical examination to identify cardiac and noncardiac disordersa

Detailed family history of heart failure, cardiomyopathy, skeletal myopathy, conduction disorders and tachyarrhythmias, sudden death

History of alcohol, illicit drugs, chemotherapy, or radiation therapya

Assessment of ability to perform routine and desired activitiesa

Assessment of volume status, orthostatic blood pressure, body mass indexa

Laboratory Evaluation
Electrocardiograma

Chest radiographa

Two-dimensional and Doppler echocardiograma

Magnetic resonance imaging to assess myocardial inflammation and fibrosis

Chemistry:

 Serum sodium,a potassium,a calcium,a magnesiuma

 Fasting glucose (glycohemoglobin in diabetes mellitus)

 Creatinine,a blood urea nitrogena

 Albumin,a total protein,a liver function testsa

 Lipid profile

 Thyroid-stimulating hormonea

 Serum iron, transferrin saturation

 Urinalysis

 Creatine kinase isoforms

 Cardiac troponin

Hematology:

 Hemoglobin/hematocrita

 White blood cell count with differential,a including eosinophils

 Erythrocyte sedimentation rate

Initial Evaluation When Specific Diagnoses Are Suspected

DNA sequencing for genetic disease; panel selection based on phenotype

Titers for infection in presence of clinical suspicion:

 Acute viral (e.g., coxsackievirus, echovirus, influenza)

 Human immunodeficiency virus

 Chagas’ disease, Lyme disease, toxoplasmosis

Coronary angiography in pts with angina who are candidates for interventiona

Serologies for active rheumatologic disease

Endomyocardial biopsy including sample for electron microscopy when suspecting specific diagnosis with therapeutic implications

Screening for sleep-disordered breathing

aLevel I Recommendations from ACC/AHA Practice Guidelines for Chronic Heart Failure in the adult.

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