Cardiac tamponade: the compression of the heart that occurs when blood or fluid builds up in the space between the myocardium (heart muscle) and the pericardium (outer covering sac of the heart). Some symptoms include anxiety or restlessness, chest pain, rapid breathing or difficulty breathing.
It is not to be confused with tapenade, which is a yummy dip made from olives. I get mixed up all the time. It's a good thing I'm not a doctor.