Myocarditis/Pericarditis

What Causes Myocarditis or Pericarditis? 

Myocarditis and pericarditis are most often caused by viruses. Other causes can include bacterial infection, fungi, and non-infectious including autoimmune disorders such as rheumatoid arthritis (JRA), systemic lupus erythematosus, dermatomyositis, Kawasaki disease, rheumatic fever, or other noninfectious diseases. 

Inflammation

Depending on the amount of inflammation involved the symptoms can range from mild to severe.

When inflammation occurs in pericarditis, it can sometimes produce fluid accumulation within the lining of the heart, this could be small or large amount. If the fluid accumulation is large, this could cause the heart not to fill as well which may require further interventions.

In myocarditis, the inflammation can damage the heart muscle. The immune system sends white blood cells, called lymphocytes and macrophages, to respond to a trigger (infectious or non-infectious). In the process of attacking the virus, bacteria, or other trigger, the white blood cells may attack the heart muscle while destroying the heart cells. Poison-like substances are released from the cells and interfere with the ability of the heart muscle to squeeze (contract). When too many heart muscle cells are damaged, the heart muscle may become severely weakened so that the heart can't pump effectively. More importantly, damaged heart muscle cells may themselves become antigens, compounds that trigger more of an immune response. This response may result in even more damage to the heart muscle cells. The process may be rapid and sometimes can result in death. However, more commonly, the heart can heal itself, but may have residual heart disease.

What Are the Symptoms of Myocarditis or Pericarditis?

Symptoms of myocarditis include:

• A history of infectious symptoms (fever, muscle aches, headache, diarrhea, sore throat, etc.)
• Fatigue
• Shortness of breath
• Abnormal heart rhythms/beats
• Lightheadedness or fainting

Symptoms of pericarditis include:

• Chest pain that is worse while lying down and improves with sitting up or leaning forward
• History of viral symptoms
• Fever
• Shortness of breath

If a significant amount of fluid is around the heart, you can also have a high heart rate and/or low blood pressure.

How Is Myocarditis or Pericarditis Diagnosed?

Diagnosis of myocarditis is hard because it looks like so many other diseases. The diagnosis is made first by the history and a physical examination by a doctor. A physical exam may show a fast heart rate, abnormal blood pressure, fast breathing rate, an abnormal examination of the heart and lungs, and sometimes an enlarged liver.

Blood tests can be obtained to help identify if inflammation is present in the body and most importantly in the heart. Special tests such as an x-ray of the chest, electrocardiogram and echocardiogram are helpful in letting know if the heart is affected. A cardiac MRI may be indicated in some cases which is another form of imaging able to look for inflammation in the heart.

The gold standard in diagnosing myocarditis is by obtaining a sample of the heart muscle via cardiac catheterization and examining the sample under a microscope. However, this is rarely done, and diagnosis is usually made by the testing stated above.

Pericarditis can best be diagnosed by history and physical exam. A physical exam may show a fast heart rate, abnormal blood pressure, fast breathing rate, an abnormal examination of the heart with a friction rub being present. In addition, ECG, chest X-ray and echocardiogram are obtained to aid in the diagnosis. Sometimes when fluid is found around the heart and is large, a needle is inserted into the area to remove the fluid. We can obtain a sample of the fluid which then can be analyzed.

How Is Myocarditis or Pericarditis Treated?

Myocarditis is mainly treated based on how severe the inflammation is affecting the heart and what the cause of the inflammation is from. Sometimes, the inflammation is part of another illness such as rheumatoid arthritis and treating the primary illness will treat the heart as well. Other times, it is so mild that nothing needs to be done. In more severe cases, anti-inflammatory drugs such as intravenous gamma globulin or steroids are used. Besides treating the inflammation, supportive care may need to be given such as medicines to make the heart pump better until it heals. In very severe cases of myocarditis with a very weak heart, machines may be required to help the heart pump. 

More commonly, the heart begins to heal itself. If there are few dead cells, the heart may improve completely, or at least in part. 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, congestive heart failure (the inability of the heart to pump enough blood to meet the demands of the body) may result.

Pericarditis treatment is focused on helping reduce chest pain and inflammation with usually over-the-counter pain reliever medications (Motrin). If recurrent, other anti-inflammatory medications can be added to help reduce inflammation. If the amount of fluid that accumulates around the heart is quite large, it may need to be removed with a needle or surgery to open the lining around the heart and let it drain.

What Are the Long-term Effects Myocarditis or Pericarditis?

With most types of pericarditis, the outlook is very good after the inflammation has resolved and the infection treated if needed to be. On some occasions, there is a recurrence of pericarditis, but this is more common with an underlying inflammatory disease.

With myocarditis, the outlook depends on the underlying cause. It is impossible to predict into which category a new case of myocarditis will fall. Regardless of mild or more severe cases, there is a period of restriction to physical activity. If there is more severe damage, more medications may be required. If the heart has been severely damaged, multiple medications may be needed to help the heart pump better, but eventually, a heart transplant may be needed.