Pericardial effusion (`fluid around the heart`) is an abnormal accumulation of fluid in the pericardial cavity. Because of the limited amount of space in the pericardial cavity, fluid accumulation leads to an increased intrapericardial pressure which can negatively affect heart function. A pericardial effusion with enough pressure to adversely a.....
An abnormal collection of fluid inside the sac that covers the heart.
<cardiology> A collection of fluid or blood in the pericardial space (inside the pericardial sac) around the heart. Some causes include congestive heart failure, cancer and autoimmune disease. ... (27 Sep 1997) ... 
Type: Term Definitions: 1. increased fluid within the pericardial sac; can cause circulatory compromise by compression of the heart; most often caused by inflammation, infection, malignancy, and uremia. Synonyms: dropsy of pericardium
Pericardial effusion: Too much fluid within the pericardium, the fibrous sac that surrounds the heart. The pericardium normally contains a small amount of pale yellow fluid which acts as a lubricant, allowing the heart to move within the chest. Common Misspellings: pericardial effution
blood or fluid leaking into the pericardium
Abnormal accumulation of fluid in the pericardial sac.
fluid build-up inside of the pericardium, affecting the performance of the heart 
a build up of excess fluid in-between the heart and the membrane that surrounds it, often due to inflammation.