What Is It?
Pericarditis is an inflammation of the pericardium, the saclike membrane around the heart. Pericarditis can be triggered by many, very different medical conditions. Often the exact cause cannot be identified. Doctors call this idiopathic pericarditis.
In many people with pericarditis, the initial trigger is a viral infection. However, the inflammation may not be a direct result of the infection. Instead, the virus may stimulate the immune system to attack and inflame the pericardium.