VIRAL ENDOCARDITIS

Autoreactive mechanisms in infective endocarditis

Infective endocarditis is not a simple interaction between a microbial agent and a cardiac valve. For the infection of a non-bacterial thrombotic vegetation, predisposition is required which is at least partially operative by a decreased suppressor T cell activity. During infection, peripheral blood natural killer cell activity is decreased, but normalizes under anti-microbial therapy. Non-major histocompatibility complex-restricted lymphocytotoxicity to isolated heart cells can be present in one third of patients. Circulating immune complexes normalize during therapy. They may be the cause of many clinical symptoms of infective endocarditis. Anti-bacterial and also anti-sarcolemmal antibodies which are cross-reactive to the bacterium are secreted in a polyclonal immune response. Anti-sarcolemmal antibodies which are cytolytic in vitro in the presence of complement may partly explain the myocardial factor of heart failure in patients with only marginal valve incompetence due to the endocarditic vegetation.

Immune reactions in infective endocarditis. I. Clinical data and diagnostic relevance of antimyocardial antibodies

Clinical data from 72 patients with infective endocarditis (41 with defined pathogen, 31 with no pathogen isolated) were analyzed with respect to the diagnostic relevance of immunologic parameters. In our patients from a rural area, no significant changes in the epidemiology and pathogenesis of infective endocarditis were observed. Antiendocardial and antisarcolemmal (ASA) antibodies were demonstrated in 60% to 100% of cases. Their frequency depended on the endocarditic pathogen and on the clinical course: in subacute or chronic endocarditis these antibodies were found regularly, in acute lethal cases their occurrence was diminished. Whereas antiendocardial antibodies are diagnostic markers of endocarditis, ASA and antimyolemmal antibodies in particular most likely indicate myocardial involvement in endocarditis. Only complement fixing antimyolemmal antibodies induced cytolysis of vital, adult, heterologous cardiac cells. Our data suggest that antibody-mediated cytolysis in vitro may also play a pathogenetic role in vivo.

Cardiac manifestations during a Coxsackie B5 epidemic

During a widespread Coxsackie B5 epidemic which occurred in Finland in the autumn of 1965 18 patients with acute myopericarditis were admitted to Kuopio Central Hospital (530 beds, representing a hospital district with 270,000 inhabitants) within a period of three months.The mean age of these patients was 28 years. Twelve were males and six were females.In 12 cases Coxsackie B5 virus and in one case Coxsackie A9 virus were isolated from the faeces. A significant increase in neutralizing antibodies or high antibody titres (>/=1:128) were noted in 16 cases against Coxsackie B5 and in one case against Coxsackie A9. In two cases the cause of the myopericarditis remained obscure.All the patients had fever. Six showed all classical criteria of pericarditis: chest pain, pericardial rub, E.C.G. changes, and radiologically observable enlargement of the heart. As regards the various criteria, E.C.G. changes were found in all cases. Signs of cardiac tamponade were observed in one patient. Five, in addition, showed aseptic meningitis.All the patients recovered. Twelve were re-examined at an average of seven months after discharge from hospital. All were symptom-free except one, who still showed E.C.G. changes.

Adenovirus endocarditis in mice

Viral endocarditis developed in 24 percent of 50 newborn mice 6 to 8 days after intraperitoneal inoculation with murine adenovirus. Typical adenovirus intranuclear inclusions were seen in heart-valve lesions, and high titers of virus were recovered from heart tissue. Furthermore, adenovirions were directly visualized by electron microscopy within endothelial cells and fibroblasts of the heart valves.

Adult heart disease due to the Coxsackie virus group B

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Endocarditis in mice infected with Coxsackie virus B4

Endocarditis has not been generally considered to be a complication of viral infection. We show that mural and valvular endocarditis can be produced in mice infected with Coxsackie virus B(4). Because this virus commonly infects man and is highly cardiotropic, it is important to know whether it produces valvular lesions in man similar to those we describe in mice.