The heart is encased in a connective tissue capsule known as the pericardium.
The pericardium contains two layers, known as the parietal and visceral pericardium, which are stacked on top of one another. Similar to a blanket, the visceral pericardium encloses the heart muscle itself. The parietal pericardium sits on top of, but is not, in the strictest sense, connected to the visceral pericardium. Because of this arrangement there is a potential space between the two layers known as the pericardial space.
When fluid (ie: blood, pus, water, etc.) leaks out into this space a pericardial effusion is present. Fluid can leak out quickly, in which case the effusion is said to be "acute"; or it can leak out gradually in which case it is said to be "chronic".
There are numerous causes of pericardial effusion some of which are listed below:
- Viral (including HIV, coxsackie, echo, adeno, ebstein-barr, and varicella viruses)
- Bacterial (including pneumococcus, neisseria meningitides, staphylococcus aureus)
- Malignancies (cancers)
- Autoimmune conditions (including connective tissue disorders, vasculitis, and drug induced)
- Uremia (from renal failure)
- Cardiovascular (cardiac surgery, myocardial infarction, aortic dissection, congestive heart failure)
- Cirrhosis (liver problems)
And this list is by no means exhaustive! There are numerous causes for pericardial effusion; sometimes the cause is unknown, in which case it is said to be "idiopathic".
The classic symptom of pericardial effusion is chest pain that is better when the patient sits up and leans forward. However, numerous other symptoms including light headedness, shortness of breath, cough, and palpitations are also seen.
Depending on how severely and quickly the effusion develops, patients may spiral into a condition known as "tamponade". When this occurs the effusion effectively chokes the heart muscle causing decreased contractile function. This can lead to decreased cardiac output and multi-organ failure if left untreated.
The classic signs of tamponade are hypotension (ie: decreased blood pressure), muffled heart sounds, and increased jugular venous pressures (you can see the jugular veins engorged with blood). These three signs are known as "Beck's triad", which is generally a late finding of tamponade (ie: the patient is almost dead!).
For non-acute effusions with no symptoms patients can be treated for their underlying condition. This will sometimes cure the effusion. However, in patients with acute presentations who have signs of cardiovascular instability (ie: low blood pressure, evidence of organ dysfunction from decreased blood flow, etc.) emergent removal of the fluid is performed. The quickest way to do this is to insert a needle under the xyphoid process and aspirate the fluid. In less acute situations, or in recurrent cases, surgical "windows" in the pericardial tissue can be created to allow the effusion to drain.
Pericardial effusions occur when fluid accumulates between the visceral and parietal pericardial layers surrounding the heart. There are numerous causes. Rapidly expanding effusions can cause cardiac tamponade and lead to cardiovascular collapse resulting in multi-organ failure if left untreated. Signs and symptoms include chest pain, shortness of breath, cough, distant heart sounds, and decreased blood pressure. Diagnosis is made off of ECG, echocardiography, and CT scan.
- Myocardial infarction (ie: heart attack)
(1) Imazio M, Brucato A, Mayosi BM, et al. Medical therapy of pericardial diseases: part II: Noninfectious pericarditis, pericardial effusion and constrictive pericarditis. J Cardiovasc Med (Hagerstown). 2010 Nov;11(11):785-94. Review.
(2) Khandaker MH, Espinosa RE, Nishimura RA, et al. Pericardial disease: diagnosis and management. Mayo Clin Proc. 2010 Jun;85(6):572-93. Review.
(3) Spodick DH. Pericarditis, pericardial effusion, cardiac tamponade, and constriction. Crit Care Clin. 1989 Jul;5(3):455-76.
(4) Mookadam F, Jiamsripong P, Oh JK, et al. Spectrum of pericardial disease: part I. Expert Rev Cardiovasc Ther. 2009 Sep;7(9):1149-57.
(5) Jiamsripong P, Mookadam F, Oh JK, et al. Spectrum of pericardial disease: part II. Expert Rev Cardiovasc Ther. 2009 Sep;7(9):1159-69.
(6) Woo KM, Schneider JI. High-risk chief complaints I: chest pain--the big three. Emerg Med Clin North Am. 2009 Nov;27(4):685-712, x.