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.

A very small percentage of patients (1 to 2 percent by some estimates) experience serious complications after use of the heart-lung machine. These complications may develop in the lungs, kidneys, brain or other areas of the body.

In the lungs, postpump syndrome can damage the tiny blood vessels where oxygen exchange takes place. It has also been associated with pulmonary edema and other signs of adult respiratory distress syndrome. In the brain, postpump syndrome is associated with confusion and memory loss in some patients. There are several theories to explain this confusion and memory loss, including the presence of tiny air bubbles (micro-emboli) that are released into the bloodstream during surgery.

As the technology behind the heart-lung machine has improved, there is some evidence that the rate of postpump syndrome is declining. Modern heart-lung machines are equipped with sophisticated filters to prevent embolism and advanced bubblers to properly oxygenate the blood.

Another theory behind postpump syndrome is concerned with unstable molecules called free radicals. Free radicals are typically produced as byproducts of metabolism. Free radicals do have a beneficial role. For example, they enable some cells to destroy foreign substances. However, in other situations the release of free radicals can cause cell and tissue damage. In postpump syndrome, it is felt that free radicals impair heart function and initiate a widespread inflammatory response. The inflammatory response can also be triggered by anesthetics, or even by the physical trauma of the surgery itself.

To address the apparent connection between free radicals and postpump syndrome, certain medications and vitamins have been used. Some physicians think that vitamin E and coenzyme Q10, for example, can help to prevent or reduce the severity of the inflammatory response associated with postpump syndrome.

Other studies are testing the safety and effectiveness of certain antibiotics in the treatment of postpump syndrome.

Recent advances in technology and techniques have allowed surgeons to perform some types of open-heart surgery without use of the pump. These operations are called off-pump surgeries (or beating-heart surgeries). The surgeon isolates the area of the heart to be worked on using stabilizers and positioners. This type of surgery is most common with CABG.

Minimally invasive bypass surgery (MIDCAB) is another type of bypass surgery that can be performed without cardiopulmonary bypass. In this operation, the surgeon operates on the heart through two incisions made in the chest.