Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Pericarditis ?
    ### Response:
    Pericarditis (PER-i-kar-DI-tis) is a condition in which the membrane, or sac, around your heart is inflamed. This sac is called the pericardium (per-i-KAR-de-um).
                
The pericardium holds the heart in place and helps it work properly. The sac is made of two thin layers of tissue that enclose your heart.
    