Pericarditis - Causes of pericarditis

It's not always clear what causes pericarditis, although a viral infection is usually suspected.

In around 90% of acute pericarditis cases, no obvious cause can be found to explain why the pericardium has become inflamed. This is known as idiopathic pericarditis.

Many cases are thought to be the result of viral infections, which can't be detected.

Viral infections

Viral infections associated with acute pericarditis include:

infections such as the common cold or viral meningitis, caused by a group of viruses known as enteroviruses
infections caused by adenoviruses, such as pneumonia or bronchitis
glandular fever
infections caused by the cytomegalovirus
herpes simplex viral infections (cold sores or genital herpes)
flu (influenza)
hepatitis C
HIV and AIDS

Other causes

Other less common causes of acute pericarditis include:

bacterial infection, particularly tuberculosis
autoimmune conditions such as rheumatoid arthritis or lupus, where the immune system attacks healthy tissues
radiotherapy – the radiation used in radiotherapy can damage the tissue of the pericardium, and breast cancer or lung cancer patients may be at particular risk
kidney failure – exactly why kidney failure causes acute pericarditis is unclear
underactive thyroid gland (hypothyroidism) – exactly why hypothyroidism causes acute pericarditis is unclear
cancer – cancer that spreads from other parts of the body to the pericardium can damage tissue
heart attacks – pericarditis can sometimes develop after a heart attack, as damaged heart muscles can irritate the pericardium
injury or irritation to the tissue of the pericardium that occurs during heart surgery
severe injury to the chest – for example, following a car accident
some medications, such as penicillin or some chemotherapy medicines, have been known to trigger acute pericarditis as a side effect in some people

Recurring pericarditis

The cause of recurring pericarditis is still unknown.

One theory suggests that your immune system may be responsible. Your immune system reacts months or even years after the initial infection that caused acute pericarditis and attacks the heart, leading to inflammation of the pericardium.

Another theory suggests that fragments of the virus may lay inactive in the tissue of the pericardium and suddenly reactivate, triggering the process of inflammation.

People treated with steroids during their first episode of acute pericarditis are six times more likely to develop recurring pericarditis than people who don't receive this treatment. Because of this, steroids are used as a last resort, if you fail to respond to other medications.