pericardiocentesis

Pericardiocentesis is a procedure in which a needle, and usually a thin catheter, is inserted into the pericardial sac to drain excess fluid. In effect it relieves a heart that is being squeezed by letting the fluid out, much like puncturing an over-tight water balloon to take the pressure off.

It serves two purposes. As an emergency treatment it relieves cardiac tamponade, where accumulated fluid is preventing the heart from filling; removing even a small amount can quickly restore blood pressure. As a diagnostic test, the drained fluid can be sent to the laboratory to look for infection, cancer cells, or the cause of an effusion.

The needle is usually advanced from just below the breastbone or the chest wall, ideally under echocardiographic guidance so the operator can see the fluid and avoid the heart, lungs, and liver. A catheter may be left in place for ongoing drainage. Risks include puncturing a heart chamber or coronary vessel, so the procedure is done with care; when fluid is loculated or recurrent, surgical drainage or a pericardial window may be preferred.