**1. Introduction**

150 Myocarditis

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Myocarditis is an acute or chronic inflammatory process that affects the myocardium in response to the action of various infectious, chemical or physical agents. In most patients the disease is self-limiting. The natural course of myocarditis varies greatly, ranging from an asymptomatic state secondary to local inflammation, through development of dilated cardiomyopathy with a variable course, to fatal heart failure due to disseminated myocarditis [Subinas et al., 2005].

In patients infected with human immunodeficiency virus (HIV) cardiovascular abnormalities are frequent but clinically discrete. Cardiologists and physicians throughout the world are increasingly reporting cardiac muscle disease in association with HIV. With current advances in HIV and acquired immunodeficiency syndrome (AIDS) management and increased survival, cardiac manifestations of HIV disease including HIV related myocardial disease will become more important and will be encountered more frequently. Because cardiac complications in HIV positive patients are often clinically inapparent, periodic screening of these patients is recommended, especially in those with low CD4 counts or receiving treatment with cardiotoxic drugs. The heart may be a marker of the HIV infected patient's overall health, and a decline in cardiac function should trigger more comprehensive evaluation. As the role of infection and inflammation in many other cardiovascular diseases is now recognized, identification of the molecular mechanisms of HIV related myocaditis might have broader implications for a wide range of patients [Azis F et al., 2010].

The diagnosis of myocarditis in HIV positive patients during an acute episode may prove difficult, due to the lack of diagnostic techniques with acceptable degrees of specificity and sensitivity. For these patients although endomyocardial biopsy is still considered the diagnostic gold standard, the developments of new imaging techniques, such as cardiac magnetic resonance imaging (CMR), and nuclear imaging by antimyosin scintigraphy have contributed greatly to the diagnosis of myocarditis.
