Myocarditis

What is myocarditis?

Myocarditis is an inflammation of the muscular walls of the heart. The inflammation damages the individual heart muscle cells. When too many heart muscle cells are damaged, the heart can't pump effectively. The process may be rapid and may result in death. More commonly, the heart begins to heal itself. Heart muscle heals by changing dead cells to scar tissue. Scar tissue does not contract and can't help the heart to pump. If enough scar tissue forms, heart failure may result.

How does it occur?

Many things can inflame the heart. Causes of myocarditis include:

• infection, especially viral infection (the most common cause)
• reactions to some drugs, such as doxorubicin and zidovudine (AZT)
• exposure to some chemicals, such as lead, arsenic, and carbon monoxide
• parasites in some parts of Central and South America
• autoimmune diseases (an over-reaction of the body's immune system), such as lupus and rheumatoid arthritis.

What starts the inflammation is not always known. When the cause of myocarditis is not known it is called idiopathic myocarditis.

What are the symptoms?

Sometimes there are no symptoms. When symptoms occur, they are the symptoms of heart failure, such as:

• running out of energy easily
• shortness of breath or trouble breathing, at first during exercise and later with any activity or even when you are resting
• waking up at night with trouble breathing or having a hard time lying flat in bed because of shortness of breath
• swollen ankles and feet and weight gain due to too much fluid in the body.

How is it diagnosed?

Your healthcare provider will ask about your symptoms and examine you. He or she will listen to your heart with a stethoscope.

The first test is usually an echocardiogram (an ultrasound scan of the heart).

Myocarditis can best be diagnosed by examining a small piece of heart muscle under a microscope. This test is called a biopsy. You will be given a local anesthetic so that you will not feel any pain during the procedure. Samples of the heart muscle are taken with a bioptome. A bioptome is a thin, flexible tube (catheter) with small cutting jaws at its tip. The bioptome is inserted through a vein in your neck and then moved through the vein into your heart. The cutting jaws remove very small pieces of muscle from inside the heart. Results will be available within 48 hours.

Once myocarditis is diagnosed, you may have blood tests to see if infection is the cause.

How is it treated?

The goals of treatment are to help the heart pump as it heals itself and to limit the amount of damage as much as possible. Drugs, and sometimes a device called an intraaortic balloon pump, are used. Complications of myocarditis, such as heart failure, can be treated if they occur.

How long do the effects last?

About one third of people who have had myocarditis return to normal after several weeks to several months. The rest have permanent damage to the heart muscle. The damage can range from slight to severe. There are effective treatments for people whose hearts do not return to normal.