Postpump syndrome (PPS) is a condition that can occur in people who have been supported by a heart-lung machine (cardiopulmonary bypass) during open-heart surgery. PPS is used to describe a variety of complications that may occur in people who have had surgeries to correct cardiac defects.

During many open heart surgeries, the lungs and heart must be stopped for surgeons to operate on the heart. While these organs are stopped, a lung-bypass machine takes over for the heart and lungs, maintaining blood flow and delivering oxygen and nutrients to the body. Cardiopulmonary bypass is used in surgeries such as coronary artery bypass graft (CABG) or heart valve surgery.