History
Onset is usually insidious but may be acute in as many as 25% of patients with dilated cardiomyopathy (DCM), especially if exacerbated by a complicating lower respiratory infection. Cough, poor feeding, irritability, and shortness of breath are usually the initial presenting symptoms. Pallor, sweating, easy fatigability, failure to gain weight, and decreased urine output may be observed. Wheezing may be an important clinical sign, suggesting congestive heart failure in infants.
Other symptoms at presentation, found in approximately 20% of patients, are as follows:
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Chest pain
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Palpitations
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Orthopnea
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Hemoptysis
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Frothy sputum
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Abdominal pain
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Syncope
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Neurologic deficit
Approximately 50% of patients with DCM have a history of preceding viral illness. A detailed family history for familial cardiomyopathy is revealing in as many as 25% of cases.
Physical Examination
In a patient with established disease, features of congestive heart failure are dominant.
The infant or young child with the disease is often tachypneic, tachycardic with weak peripheral pulses, and has cool extremities and hepatomegaly. Blood pressure is low, with a decreased pulse pressure. In extreme cases, patients may present in shock.
Older children may show dependent edema, elevated jugular venous pulses, and fine basal crepitations in the lungs.
Major cardiac findings include the following:
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Cardiomegaly
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Quiet precordium
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Tachycardia
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Gallop rhythm (S3 and/or S4)
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Accentuated P-2
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Murmurs of mitral and tricuspid regurgitation
Murmurs may be inconspicuous initially if the patient presents with acute heart failure.
Infants often present with predominantly respiratory signs and, in the absence of a precordial heave or prominent murmur, the underlying cardiac disease may remain undiagnosed until cardiomegaly is detected on a chest radiograph.
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Chest radiograph of a child with idiopathic dilated cardiomyopathy.
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Echocardiogram obtained from apical 4-chamber view revealing a dilated left atrium and left ventricle in a child with idiopathic dilated cardiomyopathy.
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This is a color Doppler echocardiogram obtained from apical 4-chamber view revealing a dilated left atrium and left ventricle with the blue jet of mitral regurgitation in a child with idiopathic dilated cardiomyopathy. Mild tricuspid regurgitation is also shown.
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This is an echocardiogram obtained from parasternal long axis view revealing a dilated left atrium and left ventricle in a child with idiopathic dilated cardiomyopathy.
Tables
- Table 1. Factors Identified as Causes of Myocardial Damage
- Table 2. Summary of Genetic Loci and Disease Genes for Familial Dilated Cardiomyopathy
- Table 3. Diagnosis of Dilated Cardiomyopathy in Children - Step I: Diagnosis
- Table 4. Diagnosis of Dilated Cardiomyopathy in Children - Step II: Identification of Any Underlying Etiology
Category Of Factors |
Specific Factors |
Viral infections (myocarditis) |
Coxsackievirus B, human immunodeficiency virus, echovirus, rubella, varicella, mumps, Epstein-Barr virus, cytomegalovirus, measles, polio |
Bacterial infections |
Diphtheria, Mycoplasma, tuberculosis, Lyme disease, septicemia |
Rickettsia |
Psittacosis, Rocky Mountain spotted fever |
Parasites |
Toxoplasma, Toxocara, Cysticercus |
Fungi |
Histoplasma, coccidioidomycoses, Actinomyces |
Neuromuscular disorders |
Duchenne or Becker muscular dystrophies, Friedreich ataxia, Kearns-Sayre syndrome, other muscular dystrophies |
Nutritional factors |
Kwashiorkor, pellagra, thiamine deficiency, selenium deficiency |
Collagen vascular diseases |
Rheumatic fever, rheumatoid arthritis, systemic lupus erythematosus, dermatomyositis, Kawasaki disease |
Hematological diseases |
Thalassemia, sickle cell disease, iron deficiency anemia |
Coronary artery diseases |
Anomalous left coronary artery from pulmonary artery, infarction |
Drugs |
Anthracycline, cyclophosphamide, chloroquine, iron overload |
Endocrine diseases |
Hypothyroidism, hyperthyroidism, hypoparathyroidism, pheochromocytoma, hypoglycemia |
Metabolic disorders |
Glycogen-storage diseases, carnitine deficiency, fatty acid oxidation defects, mucopolysaccharidoses |
Malformation syndromes |
Cri-du-chat (cat-cry) syndrome |
Clinical Pattern |
Identified Genetic Loci |
Identified Disease Genes |
Autosomal dominant (AD) |
10q21-10q23, 9q13-q22, 1q32, 15q14, 2q31, 1q11-21 |
Actin, desmin, lamin A/C |
AD with conduction defect |
1p1-1q1, 3p22-3p25 |
... |
X-linked (XL) |
Xp21 |
Dystrophin |
XL cardio-skeletal (Barth syndrome) |
Xq28 (gene G4.5) |
Tafazzin |
Approach |
Findings |
Conclusion |
Clinical suspicion |
Infants and young children: Shortness of breath, feeding difficulties, wheezing, failure to thrive, recurrent chest infections, hepatomegaly, cardiomegaly Older children: Dyspnea, dependent edema, elevated jugular venous pressure, cardiomegaly |
Probable heart disease with heart failure |
Chest radiography |
Cardiomegaly, pulmonary plethora, prominent upper lobe veins, pulmonary edema, pleural effusion, collapsed left lower lobe |
High probability of heart failure with or without chest infection |
Electrocardiography |
Low-voltage complexes |
Pericardial effusion |
Presence of Q waves and inversion of T waves in leads I, II, aVL, and V4 through V6 (anterolateral infarction pattern) |
Anomalous left coronary artery from pulmonary artery |
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Significant arrhythmia |
Dilated cardiomyopathy secondary to arrhythmia |
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Left ventricular or biventricular hypertrophy with or without left ventricular strain pattern |
Often unhelpful |
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Doppler echocardiographic studies* |
Significant congenital heart disease |
Diagnose primary disease |
Significant pericardial effusion with satisfactory left ventricular ejection fraction |
Diagnose pericardial effusion |
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Left ventricular posterior wall hypokinesia with hyperechoic papillary muscles, retrograde continuous flow into proximal pulmonary artery |
Diagnose anomalous left coronary artery from pulmonary artery |
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Dilated left ventricle (>95th percentile) with global hypokinesia (fractional shortening < 25%, ejection fraction < 50%), and no demonstrable structural heart disease |
Diagnose dilated cardiomyopathy |
Approach |
Findings |
Conclusion |
Clinical features |
Positive family history |
Genetic cause for dilated cardiomyopathy |
Acute or chronic encephalopathy, muscle weakness, hypotonia, growth retardation, recurrent vomiting, lethargy |
Inborn error of metabolism involving energy production |
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Coarse or dysmorphic features, organomegaly, skeletal abnormalities, short stature, chronic encephalopathy, cherry-red spot in eyes |
Storage diseases |
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Skeletal muscle weakness without encephalopathy |
Neuromuscular disorders |
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Blood investigations |
High blood urea nitrogen and creatinine levels, low calcium and magnesium levels, electrolyte disturbances |
Help in the initial management; occasionally point to a cause of dilated cardiomyopathy, especially in neonates |
Elevated acute-phase reactants and cardiac enzyme levels |
Myocarditis |
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Positive viral titers |
Viral myocarditis |
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Low serum carnitine levels |
Systemic carnitine deficiency |
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Hypoglycemia with low or no acidosis (ketosis) 1. High insulin levels, low free fatty acid 2. Low insulin levels, high free fatty acid |
1. Infant of diabetic mother, nesidioblastosis 2. Defect in fatty acid oxidation or carnitine metabolism |
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Hypoglycemia with moderate or high acidosis (ketosis) 1. Low or normal lactate and abnormal urine and serum organic acid levels 1. High lactate |
1. Organic (propionic, methylmalonic) acidemias, or ß-ketothiolase deficiency 2. Glycogen storage disease, Bath and Sengers syndromes, pyruvate dehydrogenase deficiency, mitochondrial enzyme deficiency |
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Hyperammonemia with acidosis |
Organic acidemias (as above) |
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Specific enzyme assay |
Confirms enzymatic defect |
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Absence of above physical and biochemical abnormalities |
Post myocarditis or idiopathic dilated cardiomyopathy |
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Cardiac catheterization |
Evaluate hemodynamics |
Useful to predict prognosis and evaluate for transplant |
Coronary angiography |
Abnormal origin of left coronary artery from pulmonary artery |
Anomalous left coronary artery from pulmonary artery |
Myocardial biopsy |
Myocyte hypertrophy and fibrosis without lymphocytic infiltrate |
Dilated cardiomyopathy |
Inflammatory cell infiltration, cell necrosis |
Myocarditis |
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Special stains |
Mitochondrial or infiltrative diseases |
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Molecular studies (on blood, fibroblasts, or myocardial cells) |
Nucleic acid hybridization studies Polymerase chain reaction studies |
Myocarditis |
DNA mutation analysis |
Identifies specific genetic defect |
