Myocarditis represents an inflammation of the heart muscle (Figure 56e), in many cases due to multiple infectious agents. The most common cause is Coxsackie B virus infection. Other viruses include ECHO, Influenza (A, B), Epstein-Barr, Mumps, Hepatitis C and HIV.

Bacterial (brucella,c.diphtheriae. haemophilus influenzae, mycoplasma pneumoniae streptococcus pneumoniae etc), rickettsial (coxiella burnetii etc), and spirochetal infections (borrelia,leptospia) may also occur.

Trypanosoma cruzi (Chagas' disease,endemic in rural Central and South America) and toxoplasma gondii) are two of the Protozoal infection causes.

Metazoal infections include trichinosis and echinococcosis.

Fungusinfections (actinomyces, cooccidiodes, histoplasma, nocardia) can occur as well.

There are toxic agents, which are causative such as anthracyclines (doxorubicin), ethanol, cytoxan and cocaine, catecholamines, interleukin-2, Alpha2 interferon, and allergic reactions to prescription (thiazides, acetazolamide, reserpine etc) and over-the-counter drugs.

Heavy metals like iron,copper ,and lead may be causative.

Autoantigens ( like inflammatory bowel disease, polymyositis, scleroderma, systemic lupus erythematosis) are examples of causative factors.

The gold standard for the diagnosis of myocarditis is the endocardial biopsy (Figure 56e). Other diagnostic tests include assays for autoimmune serum markers to identify autoimmune myocarditis.

Creatine kinase andtroponin levels may be elevated and should be determined in patients suspected of myocarditis,as well as sedimementation rate, and rheumatologic screening .

Testing for the presence ofviral genome in endocardial specimen is recommended to differentiate autoimmune from viral causes.

HIV testing is also recommended routinely.

Also actimyosin scintigrahy may be helful.

Treatment include supportive care , diuretics angiotensin-converting - inhibitor and a beta-blocker. Hospitalization may be required. Intravenous inotropic therapy or implantationof a pacemaker may be needed.

Immonosuppressive drugs have been helpful (not recommended for routine use) as has intravenous immune gamma globulin.

Patients with fulminant myocarditis may beneiitfrom short -term left ventricular support.