The pericardium is a thin, two-layered, fluid-filled sac that covers the outer surface of the heart. It shields the heart from infection or malignancy and contains the heart in the chest wall. It also prevents the heart from over-expanding when blood volume increases, which keeps the heart functioning efficiently.

Conditions that may affect the pericardium include:

• Pericarditis – inflammation of the pericardium
• Pericardial effusion - abnormal build-up of excess fluid that develops between the pericardium, the lining of the heart, and the heart itself