Hemopericardium is defined as the accumulation of blood within the pericardium, which is the sac that encloses the heart. This medical condition can be caused by chest trauma, ruptured heart vessels, or a type of cancer that spreads to the pericardium. Some possible synonyms or related terms for hemopericardium include cardiac tamponade, pericardial effusion, and pericarditis with effusion. These terms describe different aspects of pericardial fluid buildup or inflammation that can affect heart function. Ultimately, hemopericardium is a serious condition that may require emergency treatment, such as pericardiocentesis or surgery, to save a patient's life.