This article reviews the current state of consensus reached for the diagnosis of myocarditis and dilated cardiomyopathy on the basis of conventional histopathological and immunohistochemical methods for inflammatory infiltrates in addition to molecular biological methods for persistence of viral genome in endomyocardial biopsies. Additionally, a brief overview is presented stating the current knowledge on effector mechanisms of the immune system in myocarditis and dilated cardiomyopathy.

Cardiomyopathies are heart muscle diseases, which have been defined by their central hemodynamics and macropathology and divided in five major forms: dilated (DCM), hypertrophic (HCM), restrictive (RCM), right ventricular (RVCM), and nonclassifiable cardiomyopathies (NCCM). Furthermore, the most recent WHO/WHF definition also comprises, among the specific cardiomyopathies, inflammatory cardiomyopathy as a distinct entity, defined as myocarditis in association with cardiac dysfunction. Idiopathic, autoimmune, and infectious forms of inflammatory cardiomyopathy were recognized. Viral cardiomyopathy has been defined as viral persistence in a dilated heart. It may be accompanied by myocardial inflammation and then termed inflammatory viral cardiomyopathy (or viral myocarditis with cardiomegaly). If no inflammation is observed in the biopsy of a dilated heart (< 14 lymphocytes and macrophages/mm(2)), the term viral cardiomyopathy or viral persistence in DCM should be applied according to the WHF Task Force recommendations. Within the German heart failure net it is the authors' working hypothesis, that DCM shares genetic risk factors with other diseases of presumed autoimmune etiology and, therefore, the same multiple genes in combination with environmental factors lead to numerous different autoimmune diseases including DCM. Therefore, the authors' primary goal is to acquire epidemiologic data of patients with DCM regarding an infectious and inflammatory etiology of the disease. Circumstantial evidence points to a major role of viral myocarditis in the etiology of DCM. The common presence of viral genetic material in the myocardium of patients with DCM provides the most compelling evidence, but proof of causality is still lacking. In addition, autoimmune reactions have been described in many studies, indicating them as an important etiologic factor. Nevertheless, data on the proportion of patients, in whom both mechanisms play a role are still missing.A pivotal role for autoimmunity in a substantial proportion of patients with DCM is supported by the presence of organ-specific autoantibodies, inflammatory infiltrates and pro-inflammatory cytotoxic cytokines. Furthermore, familial occurrence of DCM has been described in about 20-30% of cases, with the presence of autoantibodies and abnormal cytokine profiles in first-degree relatives with asymptomatic left ventricular enlargement. This suggests the involvement of a disrupted humoral and cellular immunity early in the development of the disease. A similar pattern of humoral and cellular immune dysregulation has been described in other autoimmune diseases. There is considerable evidence that genetic factors play an important role in the pathogenesis of DCM, either as contributors to the susceptibility to environmental factors or as determinants of functional and structural changes that characterize the phenotypic expression of the disease.Yet, it is not known whether the susceptibility to immunologically mediated myocardial damage reflects the presence of genetic risk fa...

Viral infection of the heart is relatively common, usually asymptomatic and has a spontaneous and complete resolution. It can, however, in rare cases, lead to substantial cardiac damage, development of viral cardiomyopathy and congestive heart failure. Viral cardiomyopathy is defined as viral persistence in a dilated heart. It may be accompanied by myocardial inflammation and then termed inflammatory viral cardiomyopathy (or viral myocarditis with cardiomegaly). If no inflammation is observed in the biopsy of a dilated heart (<14 lymphocytes and macrophages/mm ) the term viral cardiomyopathy or viral persistence in dilated cardiomyopathy should be applied. The diagnosis of myocarditis and viral cardiomyopathy can be made only by endomyocardial biopsy, implementing the WHO/WHF criteria, and PCR techniques for identification of viral genome. The most frequent cardiotropic viruses detected by endomyocardial biopsy are Parvo B19, enteroviruses, adenoviruses, cytomegalovirus, and less frequently Epstein-Barr virus, and influenza virus.

There are many causes of pericardial effusion and it is useful to classify them etiologically, since this disorder is the most common pathologic process involving the pericardium. This report details our experience with pericardioscopy and epicardial biopsy in 101 patients with pericardial effusions in whom pericardioscopy was performed. By means of clinical data and polymerase chain reaction we tried to elucidate the etiology of the pericardial effusion which were classified as follows: we found 41 effusions to be induced by primary malignant tumors or tumors metastatic to the pericardium. Specific diagnosis of viral and bacterial pericarditis was established in 17 patients by examination of the pericardial effusion with PCR, where we found 3 patients positive for adenovirus, 5 patients positive for cytomegalovirus, 2 patients positive for enterovirus-RNA and 5 patients positive for borrelia Burgdorferi-DNA. Additionally, idiopathic effusions (lymphocytic and autoreactive) were seen in 35 patients. In summary immunological and molecular biology investigations seem to provide an additional tool in the diagnostic of pericardial effusion with unknown etiology. If we focus on the ELISA results, there is some evidence, that the demonstration [table: see text] of activation markers and soluble mediators of inflammation such as Il-6, Il-8 and IFN-gamma in pericardial effusion and the simultaneously lack of these mediators in sera of the patients first may be helpful in the discrimination of autoreactive and lymphocytic effusion. Second, this cytokine pattern or distribution indicates a possible local inflammatory process, where these cytokines were all released from activated T lymphocytes present in lymphocytic effusion. In the future, this may have therapeutic implications.

In the report of the 1995 World Health Federation/International Society and Federation of Cardiology (WHF/ISFC) Task Force on the Definition and Classification of Cardiomyopathies, the definition of heart muscle diseases was updated. Idiopathic, autoimmune, and infectious forms of inflammatory cardiomyopathy are now recognized in this definition. Enteroviruses, adenoviruses and cytomegaloviruses are considered as main etiopathological factors in the pathogenesis of inflammatory heart disease. A wide range of different assays have been and are currently being used, either alone or in combination, to assay for the presence of enteroviral RNA and/or DNA of cytomegalo- and adenoviruses in endomyocardial biopsy and explanted heart samples. The prevalence of cardiotropic viruses in endomyocardial biopsies of patients with clinically suspected inflammatory cardiomyopathy varies widely: enteroviral genome was detected in endomyocardial biopsies of 3 to 53% of patients, cytomegaloviral DNA was detected in 3 to 40% of patients with inflammatory heart disease and adenoviruses in 3 to 23% of the patients. This report summarizes the methods that have been used and the results of molecular biological investigation with polymerase chain reaction, which were reported by several groups over the last years. Taking this together it seems to be clear that the improvement of molecular biological techniques and the experience of people working with these methods will lead to more reliable results on prevalence, persistence and the diagnostic value of these investigations. These findings have to be taken into account in future diagnostic and therapeutic studies in the field of cardiomyopathies.