Right heart catheterization (also known as pulmonary artery catheterization or Swan-Ganz catheterization) is a common procedure in critically ill patients. The catheter is a long thin hollow tube that is placed through a central venous catheter and is then guided through the chambers of the heart and into the large blood vessels of the lungs. The catheter is left in place in a pulmonary (lung) artery. This catheter measures pressures in the heart and large blood vessels and checks how well the heart is working. In patients with a lot of water in their lungs due to heart failure or inflammation of the lungs, the catheter can help monitor treatments to prevent more water from accumulating in the lungs.