Understanding the Pericardium (Pericardial Sac)

Your heart is surrounded by a double-layered membrane, called the pericardium or pericardial sac. This membrane keeps your heart in place in your chest cavity, restricts the expansion of your heart when your blood volume increases, and helps to protect your heart. The inner layer of the pericardium is attached to your heart muscle.

There is a very small amount of fluid called pericardial fluid in the pericardial sac. This fluid helps to decrease friction between the pericardial layers. It also allows 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.

Pericardiocentesis is an invasive procedure. It uses a needle and catheter to obtain fluid from your 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, cancer, or the cause of extra fluid surrounding your heart. The procedure can also be used to ease symptoms such as shortness of breath.

When too much fluid is trapped in your pericardium, this is called pericardial effusion. This can prevent your heart from pumping normally because the extra fluid causes compression. Pericardial effusion can lead to a life-threatening condition called cardiac tamponade. In this condition, your heart becomes too compressed to function normally. Cardiac tamponade is life threatening and must be treated immediately.

There are many causes for the buildup of fluid in the pericardium, including:

  • kidney failure
  • hypothyroidism, or underactive thyroid
  • radiation therapy for cancers
  • medications such as hydralazine for hypertension, isoniazid (Nydrazid) for tuberculosis, and phenytoin (Dilantin) for seizures
  • piercing or blunt trauma near the heart
  • cancer of the heart or pericardium or metastatic cancer from other organs
  • autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis
  • viral, bacterial, fungal, or parasitic infections
  • congestive heart failure
  • ventricular aneurysm rupture

This procedure will be performed in a hospital. Tell your doctor about any medications and supplements you take, ask your doctor if you should adjust your medications the day of the procedure, and tell your doctor if you are diabetic. You will usually not be allowed anything to eat or drink for six hours before your appointment.

You will be allowed to go home after the procedure, but you will need someone else to drive you home.

A pericardiocentesis is usually performed in an intensive care unit or cardiology department in a hospital, but it may be done at your bedside or in the emergency department if you experience 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 your pericardial sac. You might feel some pressure while the needle goes in. It is guided by echocardiogram, which gives your 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, your doctor 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, your doctor, your outlook, and the cause of effusion, more invasive surgical drainage than needle pericardiocentesis may be necessary.

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
  • bleeding
  • infection
  • 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, since you won’t be allowed to drive yourself directly following the procedure.

If the drained fluid needs to be tested for infections or cancer, your doctor will send it to a laboratory. If the fluid shows signs of an infection, the infection 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 your pericardium is inflamed for no apparent reason. This is called idiopathic pericarditis.

In some people, 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 prevent repeated pericardiocentesis. Sometimes a surgical procedure called pericardial sclerosis is necessary to close the space around your heart so fluid can’t accumulate in the sac surrounding your heart.

If abnormal results are found in the fluid, your doctor may be able to determine the cause of fluid accumulation. Talk with your doctor about what your results mean and whether there is a chance of the fluid coming back. They can discuss your treatment options with you.