Understanding the Pericardium (Pericardial Sac)
The heart is surrounded by a double-layered membrane called the pericardium or pericardial sac. It functions like a sac around the heart, keeping the heart in place in the chest cavity and restricting expansion of the heart when blood volume increases. help protect it. The inner layer of the pericardium is actually attached to the heart muscle. There is a very small amount of fluid called pericardial fluid in the pericardial sac which helps decrease friction between the pericardial layers and allow for smooth movement of the heart when it beats.
Pericardiocentesis, also known as a pericardial tap, is a test used to diagnose issues related to the pericardium.
What is Pericardiocentesis?
Pericardiocentesis is an invasive procedure that uses a needle and catheter to obtain fluid from the pericardium. The fluid can then be sent to a laboratory for microscopic examination for abnormal cells.
This test is often used to help diagnose an infection or cancer, help ease symptoms such as shortness of breath, or to aid in diagnosing the cause of extra fluid surrounding the heart.
When too much fluid is trapped in the pericardium, this is called pericardial effusion. This can prevent the heart from pumping normally because the extra fluid causes compression. Pericardial effusion can lead to a life-threatening condition called cardiac tamponade, when the heart becomes too compressed to function normally. Cardiac tamponade is life-threatening and must be treated immediately.
Causes of Pericardial Effusions
There are many causes for the buildup of fluid in the pericardium and a few of these are:
- kidney failure
- hypothyroidism (underactive thyroid)
- radiation therapy for cancers
- medications—hydralazine for hypertension; isoniazid for tuberculosis; dilantin for seizures
- trauma (piercing or blunt near the heart)
- cancer (heart or pericardium or metastatic cancer from other organs)
- autoimmune disease (systemic lupus erythematosus, Rheumatoid arthritis)
- viral, bacterial, fungal infections or parasitic infections
How do I Prepare for Pericardiocentesis?
This procedure will be performed in a hospital. Tell your doctor about any medications and supplements you take, and if you are diabetic, ask your doctor if you should adjust your medications the day of the procedure. Typically, you will not be allowed anything to eat or drink for six hours before the appointment. You will be allowed to go home after the procedure, but will need someone else to drive you home.
What Can I Expect During the Procedure?
A pericardiocentesis is usually performed in an intensive care unit or cardiology department in a hospital, but may be done at the bedside or in the emergency room if a patient experiences pericardial effusion.
You will be asked to lie down on an exam table and positioned at a 60-degree angle. An IV will be started to give you any fluids or medications in case you have a severe drop in blood pressure or slowed heartbeat during the procedure. The skin below and around your breastbone will be cleaned and a local numbing agent will be applied. You may also be given a sedative, but you will remain awake for the procedure.
A needle is then inserted into the pericardial sac. You might feel some pressure while the needle goes in. It is guided by echocardiogram, which gives the doctor a moving picture of your heart, similar to an ultrasound. This will also help monitor fluid drainage. Once the needle has been placed correctly, the surgeon will replace it with a very thin tube known as a catheter. The procedure itself takes 20 to 60 minutes.
The catheter then stays in place to let fluid drain through it into a container, sometimes for several hours. Once the fluid has drained, the catheter is removed.
Depending on the institution, the physician, the patient’s prognosis, and the cause of the effusion, more invasive surgical drainage instead of needle pericardiocentesis may be necessary.
Are There Any Possible Side Effects?
As with any invasive procedure, there are risks to pericardiocentesis. Your doctor will go over all the risks and have you sign a consent form before the procedure.
Possible risks include:
- heart attack
- collapsed lung
- abnormal heart rhythm
- puncture of the heart muscle
After the procedure, the site of the catheter should be checked regularly for any signs of infection. Your blood pressure and pulse will be monitored after the procedure, and your doctor will decide when to send you home. If you were given a sedative, someone will have to drive you home as you will not be allowed to drive yourself directly following the procedure.
Testing the Fluid
If the drained fluid needs to be tested for infections or cancer, your doctor will send it to a laboratory. If it is an infection, it may be due to an autoimmune disorder, hypothyroidism, rheumatic fever, immunosuppressants, chest radiation, cancer, or kidney failure. Sometimes the cause of the infection is unknown, and the pericardium is inflamed for no apparent reason; this is called idiopathic pericarditis.
In some patients, especially those with advanced cancer, fluid may continue to build up in the pericardium. A catheter may be put in place to ensure continual drainage and to avoid repeated pericardiocentesis. Sometimes a surgical procedure called pericardial sclerosis is necessary to close the space around the heart so fluid cannot accumulate in the sac surrounding the heart.
What do Abnormal Results Mean?
If abnormal results were found in the fluid, the cause of fluid accumulation can be determined. These diseases can include:
- cardiac trauma
- pericarditis, or infection in the heart
- congestive heart failure
- ventricular aneurysm rupture
Talk with your doctor about what your results mean, and whether there is a chance of the fluid coming back. She can discuss your treatment options with you.