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Inflammatory cardiomyopathies, particularly viral myocarditis, have served as models to understand the development of heart failure. More than 70 different specific cardiomyopathies associated with general systemic disease, neuromuscular disorders, hypersensitivity and toxic reactions, and the peripartum state have been described. A list of causes associated with the development of cardiomyopathy is presented in Fig. 35–1. When they are considered as a group, these disorders are infrequent; considered individually, they are rare. Cardiomyopathy associated with HIV disease is considered in Chap. 93.

Figure 35–1

Various etiologies that can lead to cardiomyopathy.



In its most literal sense, myocarditis means inflammation of the myocardium. As early as 1806, a relationship between infection (diphtheria) and chronic heart disease was postulated, but it was not until the 1970s, with the advent of endomyocardial biopsy, that the diagnosis of myocarditis could be established during life. Multiple infectious etiologies (Table 35–1)1 have been implicated as the cause of myocarditis, the most common being viral, specifically, the enterovirus coxsackie B. In the majority of patients, active myocarditis remains unsuspected because the cardiac dysfunction is subclinical and self-limited. The discovery of myocarditis in 1% to 9% of routine postmortem examinations suggests that myocarditis is a major cause of sudden, unexpected death.2

TABLE 35–1. Causes of Myocarditis

Infection by cardiotropic viruses prompted the initial hypothesis that the viral infection was responsible for myocardial injury. However, several investigators noted that cardiac dysfunction increased after the eradication of the infective agent and speculated that the pathogenesis of myocarditis can be caused by two distinct phases of myocardial cell damage—the first caused by direct viral infection and the second caused by the host's immune response (Fig. 35–2). Support for this theory comes initially from the work of Woodruff,3 who noted that the histologic evidence of cardiac injury in coxsackie B infection appeared only after ...

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