Pericarditis - Causes 

Acute pericarditis

In around 90% of cases of acute pericarditis, no obvious cause can be found to explain why the pericardium has become inflamed. Many cases are thought to be the result of viral infections, which current diagnostic technology is generally unable to detect.

Viral infections

Viral infections associated with acute pericarditis include:

• infections such as the common cold or viral meningitis, which are caused by a group of viruses known as enteroviruses
• infections caused by adenoviruses, such as such as pneumonia or bronchitis
• glandular fever 
• infections caused by the cytomegalovirus
• herpes simplex viral infections (cold sores or genital herpes)
• influenza
• slapped cheek syndrome
• 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 or lung cancer patients may be at particular risk
• kidney failure (when the kidneys stop working) – 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 – for example, penicillin or some chemotherapy medicines have been known to trigger acute pericarditis as a side effect in some people

Recurring pericarditis

Despite being a relatively common condition, recurring pericarditis remains a poorly understood condition with little known about the cause.

One theory is that your immune system may be responsible. The theory argues that something goes wrong with your immune system many months or years after the initial infection that caused your first episode of acute pericarditis. It starts to produce infection-fighting antibodies that are meant to be used to fight the virus, but instead are sent to the heart, leading to inflammation of the pericardium. Exactly why the immune system would behave in this way is unclear.

Another theory is that fragments of the virus may lay dormant (inactive) in the tissue of the pericardium and then suddenly reactivate, triggering the process of inflammation.

What is known, is that people treated with corticosteroids during their first episode of acute pericarditis are six times more likely to go on to develop recurring pericarditis than people who do not receive this treatment. Because of this, corticosteroids are used as a last resort, if you fail to respond to other medications.