A cardiomyopathy is an intrinsic disease of the heart muscle and is not associated with other forms of heart disease (Table 147-1). There are three types of cardiomyopathy based on anatomic and functional features: 1.
2.
3.
Dilated cardiomyopathies are the most common. They are often idiopathic, but may be due to infection (echovirus or Coxsackie B virus) or be postinfectious, familial, or secondary to systemic disease or to cardiotoxic drugs. Hypertrophic cardiomyopathies are usually familial with autosomal dominant inheritance, but may occur sporadically. Restrictive cardiomyopathies are rare; they may be idiopathic or associated with systemic disease (Table 147-2).
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Dilated cardiomyopathies result in enlargement of the leftventricle only or of both ventricles. Myocardial contractility is variably decreased. Children with dilated cardiomyopathy present with signs and symptoms of inadequate cardiac output and heart failure. Tachypnea and tachycardia are present on examination. Peripheral pulses are often weak because of a narrow pulse pressure. Rales may be audible on auscultation. The heart sounds may be muffled, and an S3 is often present. Concurrent infectious illness may result in circulatory collapse and shock in children with dilated cardiomyopathies.
Hypertrophic cardiomyopathy is initially difficult to diagnose. Infants, but not older children, frequently present withsigns of heart failure. Sudden death may be the initial presentation in older children. Dyspnea, fatigue, chest pain,syncope or near-syncope, and palpitations may be present.A murmur is heard in more than 50% of children referred after identification of an affected family member. Restrictive cardiomyopathies are relatively rare in pediatrics. Presentingsymptoms usually include dyspnea exacerbated by a respiratory illness, syncope, hepatomegaly, and an S4 heart sound on examination.
Duchenne muscular dystrophy Other muscular dystrophies (Becker, limb-girdle) Myotonic dystrophy Kearns-Sayre syndrome (progressive external ophthalmoplegia) Carnitine deficiency syndromes Endocardial fibroelastosis Mitochondrial myopathy syndromes Familial dilated cardiomyopathy (dominant, recessive, X-linked) Familial hypertrophic cardiomyopathy Familial restrictive cardiomyopathy Pompe disease (glycogen storage)
Viral (e.g., coxsackievirus infection, mumps, Epstein-Barr virus infection, influenza, parainfluenza infection, measles, varicella, HIV infection)
Rickettsial (e.g., psittacosis, Coxiella infection, Rocky Mountain spotted fever)
Bacterial (e.g., diphtheria, Mycoplasma infection, meningococcal disease, leptospirosis, Lyme disease)
Parasitic (e.g., Chagas disease, toxoplasmosis)
Hypothyroidism Hyperthyroidism Pheochromocytoma Mitochondrial myopathies and oxidative respiratory chain defects Type II, X-linked 3-methylglutaconic aciduria
HIV, Human immunodeficiency virus.
Etiology Infectious Sporadic Infiltrative (amyloidosis, sarcoidosis) Metabolic Inherited (autosomal dominant) Noninfiltrative (idiopathic, familial) Toxic
Storage disease (hemochromatosis, Fabry Idiopathic
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