Which condition refers to swelling around the heart?

The condition that refers to swelling around the heart is hydropericardium. This condition involves an accumulation of fluid within the pericardial sac, which is the fibrous sac that surrounds the heart. This fluid buildup can put pressure on the heart, potentially impacting its ability to function effectively, leading to various cardiac complications.

Understanding how hydropericardium occurs is also important. It can result from various issues, such as heart failure, infection, inflammation, or trauma, which might lead to fluid leakage into the pericardial space.

In contrast, lymphedema is swelling that occurs in a limb due to the accumulation of lymph fluid, often following removal of or damage to lymph nodes. Hydrothorax is the accumulation of fluid in the pleural cavity of the lungs, while anasarca refers to widespread swelling in the body's tissues due to fluid retention, which is not specific to the heart. Thus, hydropericardium is specifically related to fluid accumulating around the heart itself, making it the correct answer.