Pericardial tamponade is the compression of the heart that occurs when blood or fluid builds up in the space between the myocardium and the pericardium, which is the outer covering sac of the heart. If the fluid significantly elevates the pressure on the heart it will prevent the heart's ventricles from filling properly. This in turn leads to a low stroke volume. The end result is ineffective pumping of blood, shock, and often death. Causes of pericardial tamponade include hypothyroidism; physical trauma, either penetrating trauma involving the pericardium or blunt chest trauma; pericarditis, which is inflammation of the pericardium; iatrogenic trauma during an invasive procedure; and myocardial rupture.
Pericardial tamponade is an emergency condition caused by a large or uncontrolled buildup of fluid inside the pericardium. As the pericardium is made of fibrous tissue that does not stretch, once fluid begins to enter the pericardial space, pressure starts to increase. If fluid continues to accumulate, then with each successive diastolic period, less and less blood enters the ventricles, as the increasing pressure presses on the heart and forces the septum to bend into the left ventricle, leading to decreased stroke volume. If pericardial tamponade is left untreated, cardiac arrest may occur. The life-saving treatment consists of pericardiocentesis, which is a procedure where fluid is aspirated from the pericardium.