Myocarditis: Inflammatory processes of the muscular walls of the heart (MYOCARDIUM) which result in injury to the cardiac muscle cells (MYOCYTES, CARDIAC). Manifestations range from subclinical to sudden death (DEATH, SUDDEN). Myocarditis in association with cardiac dysfunction is classified as inflammatory CARDIOMYOPATHY usually caused by INFECTION, autoimmune diseases, or responses to toxic substances. Myocarditis is also a common cause of DILATED CARDIOMYOPATHY and other cardiomyopathies.Coxsackievirus Infections: A heterogeneous group of infections produced by coxsackieviruses, including HERPANGINA, aseptic meningitis (MENINGITIS, ASEPTIC), a common-cold-like syndrome, a non-paralytic poliomyelitis-like syndrome, epidemic pleurodynia (PLEURODYNIA, EPIDEMIC) and a serious MYOCARDITIS.Enterovirus B, Human: A species of ENTEROVIRUS infecting humans and containing 36 serotypes. It is comprised of all the echoviruses and a few coxsackieviruses, including all of those previously named coxsackievirus B.Autoimmune Diseases: Disorders that are characterized by the production of antibodies that react with host tissues or immune effector cells that are autoreactive to endogenous peptides.Myocardium: The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.Enterovirus InfectionsCardiomyopathy, Dilated: A form of CARDIAC MUSCLE disease that is characterized by ventricular dilation, VENTRICULAR DYSFUNCTION, and HEART FAILURE. Risk factors include SMOKING; ALCOHOL DRINKING; HYPERTENSION; INFECTION; PREGNANCY; and mutations in the LMNA gene encoding LAMIN TYPE A, a NUCLEAR LAMINA protein.Chagas Cardiomyopathy: A disease of the CARDIAC MUSCLE developed subsequent to the initial protozoan infection by TRYPANOSOMA CRUZI. After infection, less than 10% develop acute illness such as MYOCARDITIS (mostly in children). The disease then enters a latent phase without clinical symptoms until about 20 years later. Myocardial symptoms of advanced CHAGAS DISEASE include conduction defects (HEART BLOCK) and CARDIOMEGALY.Enterovirus: A genus of the family PICORNAVIRIDAE whose members preferentially inhabit the intestinal tract of a variety of hosts. The genus contains many species. Newly described members of human enteroviruses are assigned continuous numbers with the species designated "human enterovirus".Acute Disease: Disease having a short and relatively severe course.Cardiovirus Infections: Infections caused by viruses of the genus CARDIOVIRUS, family PICORNAVIRIDAE.Encephalomyocarditis virus: The type species of CARDIOVIRUS causing encephalomyelitis and myocarditis in rodents, pigs, and monkeys. Infection in man has been reported with CNS involvement but without myocarditis.Rats, Inbred LewCardiac Myosins: Myosin type II isoforms found in cardiac muscle.Endocardium: The innermost layer of the heart, comprised of endothelial cells.Biopsy: Removal and pathologic examination of specimens in the form of small pieces of tissue from the living body.Reoviridae Infections: Infections produced by reoviruses, general or unspecified.Pericarditis: Inflammation of the PERICARDIUM from various origins, such as infection, neoplasm, autoimmune process, injuries, or drug-induced. Pericarditis usually leads to PERICARDIAL EFFUSION, or CONSTRICTIVE PERICARDITIS.Myosins: A diverse superfamily of proteins that function as translocating proteins. They share the common characteristics of being able to bind ACTINS and hydrolyze MgATP. Myosins generally consist of heavy chains which are involved in locomotion, and light chains which are involved in regulation. Within the structure of myosin heavy chain are three domains: the head, the neck and the tail. The head region of the heavy chain contains the actin binding domain and MgATPase domain which provides energy for locomotion. The neck region is involved in binding the light-chains. The tail region provides the anchoring point that maintains the position of the heavy chain. The superfamily of myosins is organized into structural classes based upon the type and arrangement of the subunits they contain.Virus Diseases: A general term for diseases produced by viruses.Heart: The hollow, muscular organ that maintains the circulation of the blood.Cardiomyopathies: A group of diseases in which the dominant feature is the involvement of the CARDIAC MUSCLE itself. Cardiomyopathies are classified according to their predominant pathophysiological features (DILATED CARDIOMYOPATHY; HYPERTROPHIC CARDIOMYOPATHY; RESTRICTIVE CARDIOMYOPATHY) or their etiological/pathological factors (CARDIOMYOPATHY, ALCOHOLIC; ENDOCARDIAL FIBROELASTOSIS).Giant Cells: Multinucleated masses produced by the fusion of many cells; often associated with viral infections. In AIDS, they are induced when the envelope glycoprotein of the HIV virus binds to the CD4 antigen of uninfected neighboring T4 cells. The resulting syncytium leads to cell death and thus may account for the cytopathic effect of the virus.Edema, Cardiac: Abnormal fluid retention by the body due to impaired cardiac function or heart failure. It is usually characterized by increase in venous and capillary pressure, and swollen legs when standing. It is different from the generalized edema caused by renal dysfunction (NEPHROTIC SYNDROME).Mice, Inbred BALB CDisease Models, Animal: Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.Trypanosoma cruzi: The agent of South American trypanosomiasis or CHAGAS DISEASE. Its vertebrate hosts are man and various domestic and wild animals. Insects of several species are vectors.Parvovirus B19, Human: The type species of ERYTHROVIRUS and the etiological agent of ERYTHEMA INFECTIOSUM, a disease most commonly seen in school-age children.Fatal Outcome: Death resulting from the presence of a disease in an individual, as shown by a single case report or a limited number of patients. This should be differentiated from DEATH, the physiological cessation of life and from MORTALITY, an epidemiological or statistical concept.