Myocarditis is inflammation of the heart muscle.

See also: Pediatric myocarditis

Myocarditis is an uncommon disorder that is usually caused by viral infections that reach the heart, including those due to the Coxsackie virus, adenovirus, and echovirus. It may also occur during or after various viral, bacterial, or parasitic infections (such as polio, influenza, or rubella).

When you have an infection, your body's immune system produces special cells that release certain chemicals to fight off disease. If the infection affects your heart, the disease-fighting cells enter the heart. However, the chemicals they produce can damage heart muscle, causing it to become thick, swollen, and weak. This leads to symptoms of heart failure.

Other causes of myocarditis may include:

• Allergic reactions to certain medications
• Being around certain chemicals
• Certain diseases that cause inflammation throughout the body

There may be no symptoms. Symptoms thay may occur include:

• Fever and other signs of infection including headache, muscle aches, sore throat, diarrhea, or rashes
• Chest pain that may resemble a heart attack
• Joint pain or swelling
• Abnormal heart beats
• Fatigue
• Shortness of breath
• Leg swelling

Additional symptoms that may be associated with this disease:

• Fainting, often related to irregular heart rhythms
• Low urine output

A physical examination may reveal the following:

• Rapid heartbeat (tachycardia)
• Abnormal heart beats or abnormal heart sounds (murmurs, extra heart sounds)
• Fluid in the lungs
• Swelling (edema) in the legs

Tests used to diagnosis myocarditis include:

• Electrocardiogram (ECG)
• Chest x-ray
• Ultrasound of the heart (echocardiogram)
• 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

Treatment is aimed at the underlying cause. Treatment may involve:

• Antibiotics
• Anti-inflammatory medicines to reduce swelling
• Diuretics to remove excess water from the body
• Low salt diet
• Reduced activity

If the heart muscle is very weak, medicines to treat heart failure are also prescribed. Abnormal heart rhythms may require the use of additional medications, a pacemaker, or defibrillator. If a blood clot is in the heart chamber, blood thinning medicine is given as well.

How well a patient does depends on the cause and the person's overall health. The outlook varies. Some may recover completely, while others may have permanent heart failure.

• Heart failure
• Pericarditis
• Cardiomyopathy

Call your health care provider if symptoms of myocarditis occur, especially after a recent infection.

Seek immediate medical help if you have severe symptoms or have been diagnosed with myocarditis and have increased swelling, chest pain, difficulty breathing, or other concerning symptoms.

Prompt treatment of causative disorders may reduce the risk of myocarditis.