Pericarditis is the inflammation and irritation of the pericardium, the thin sac-like membrane that surrounds the heart. Often, pericarditis causes chest pain and, sometimes, other symptoms. Acute chest pain associated with pericarditis occurs when the irritated layers of the pericardium rub against each other.

Usually, pericarditis starts suddenly, but does not last long (acute). When symptoms manifest more gradually or continue, pericarditis is considered chronic.
Most cases are mild and, in general, improve without treatment. Treatment of more serious cases may include the administration of medications and, rarely, surgery. Early diagnosis and treatment can help reduce the risk of long-term complications from pericarditis.