Infection of the heart muscle.
Depends on the organism.
An enormous number of organisms can involve the heart. NEJM review (PubMed).
A list, not inclusive, but of the important ones to consider, include:
- Viral: Adenovirus, Coxsackie A, Coxsackie B, Cytomegalovirus, Echovirus, Epstein-Barr, Hepatitis B, Hepatitis C, Herpes simplex, Human immunodeficiency virus, Influenza A and B, Lymphocytic choriomeningitis, Mumps, Nonpolio enterovirus, Parvovirus B19, Polio, Respiratory Syncytial virus, Rubella, Rubeola, Varicella-zoster.
-Bacteria and rickettsiae: Borrelia burgdorferi, Brucella, Chlamydia pneumoniae, Chlamydia psittaci, Clostridium perfringens, Corynebacterium diphtheriae, Coxiella burnetti, Ehrlichia, Legionella pneumophila, Listeria monocytogenes, Mycobacterium tuberculosis, Mycoplasma pneumoniae, Neisseria meningitidis, Orientia tsutsugamushi, Rickettsia prowazekii, Rickettsia rickettsii, Salmonella, Staphylococcus aureus, Streptococcus pyogenes, Treponema pallidum, Tropheryma whippeli.
Depends on the presumed etiology. Bed rest is important, do not stress that heart.
Fortunately the heart is hard to infect with bacteria. Usually acute disease of most of the bacterial organisms listed above leads to death. For the viral causes, usually get the diagnosis after the disease had come and gone and we have to deal with the resultant 'idiopathic' cardiomyopathy. It is rare indeed to get a positive and treatable acutely from a cardiac biopsy.