Myocarditis is an inflammation of the heart muscle.

Myocarditis is an uncommon disorder that is usually caused by viral infections such as coxsackie virus, adenovirus, and echovirus. It may also occur during or after various viral, bacterial, or parasitic infections (such as polio, influenza, or rubella).

The condition may also be caused by exposure to chemicals or allergic reactions to certain medications and it can be associated with autoimmune diseases.

The heart muscle becomes inflamed and weakened. This causes symptoms of heart failure.

• History of preceding viral illness
• Fever
• Chest pain that may resemble a heart attack
• Joint pain or swelling
• Abnormal heart beats
• Fatigue
• Shortness of breath
• Leg swelling
• Inability to lie flat

Total absence of symptoms is common

Additional symptoms that may be associated with this disease:

• Fainting, often related to arrhythmias
• Low urine output
• Other symptoms consistent with a viral infection -- headache, muscle aches, diarrhea, sore throat, rashes

A physical examination may detect a rapid heartbeat (tachycardia) or abnormal heart beats, abnormal heart sounds (murmurs, extra heart sounds), fluid in the lungs and fluid in the skin of the legs. In addition, other signs suggestive of an infection may be present: fever, rashes, red throat, itchy eyes, swollen joints.

Tests used in the diagnosis of myocarditis include:

• Electrocardiogram (ECG)
• Chest x-ray
• Ultrasound of the heart (echocardiogram) -- may show weak heart muscle, an enlarged heart, or fluid surrounding the heart.
• White blood cell count
• Red blood cell count
• Blood cultures for infection
• Blood tests for antibodies against the heart muscle and the body itself
• Heart muscle biopsy - rarely performed