The heart is made up of 3 layers. The innermost layer is called the endocardium. This layer forms the inner lining of cavities and also constitutes valves, which are very important for pumping. The second layer around the endocardium is called the myocardium. This is a layer of the heart muscle.
You can read more about how blood flows in your heart in our article here and read more about how heart valves function here and the cardiac cycle here.
The outermost layer is known as the pericardium. This layer forms the outer shell and protects the heart. The pericardium is a double-layered sac-like structure, with a tiny amount of fluid in between for lubrication.
The quantity of fluid between these layers increases when there is injury or trauma to the chest, internal bleeding or inflammation due to disease in the pericardium. Instead of acting like lubrication for the heart, it now starts building resistance to the heart’s pumping action. This puts more pressure on the heart and starts affecting its pumping ability. This is known as pericardial effusion.
When there’s too much fluid inside the pericardium, the heart has no room to expand and fill up blood. This is like trying to blow a balloon inside a bottle. This condition is known as cardiac tamponade and can cause the heart to stop in a matter of minutes to hours if left untreated.
Inflammation (the reaction of your tissues to an irritant or infection) of the pericardium is called pericarditis. Inflammation causes fluid to build up in the tissue, accumulating in the pericardial space, causing pericardial effusion.
Some common causes include:
Pericardial effusion is a severe condition with high risk, and it's always recommended to get medical care. However, every instance of the pericardial effusion may not be life-threatening or even symptomatic. The risk level depends on several factors, like causative agents, the amount of fluid accumulation, and the pace of fluid accumulation. A smaller amount of fluid in an effusion may resolve on its own.
A suddenly forming effusion that is filling up fast is certainly a cause for alarm and could result in serious complications or death. On the other hand, a slowly filling effusion may take weeks or months before symptoms start showing. Your doctor will evaluate the cause of the effusion and the severity or risk and suggest the best course of treatment.
When the pericardial effusion is small or happens slowly, there may not be much or any symptoms seen. However, if it fills up fast, cardiac tamponade and stoppage of the heart can occur.
The main symptoms of pericardial effusion include:
You can read more about the diagnosis and treatment of pericardial effusion and other pericardial conditions in our article here.