Shunt (medical)

Overview
In medicine, a shunt is a hole or passage which moves, or allows movement of, fluid from one part of the body to another. The term may describe either congenital or acquired shunts; and acquired shunts (sometimes referred to as iatrogenic shunts) may be either biological or mechanical.
 * Cardiac shunts may be described as right-to-left, left-to-right or bidirectional, or as systemic-to-pulmonary or pulmonary-to-systemic.
 * Cerebral shunt: In cases of hydrocephalus, a one-way valve is used to drain excess cerebrospinal fluid from the brain and carry it to other parts of the body. This valve usually sits outside the skull, but beneath the skin, somewhere behind the ear.
 * Pulmonary shunts exist when there is normal perfusion to an alveolus, but ventilation fails to supply the perfused region.
 * A portosystemic shunt (PSS), also known as a liver shunt, is a bypass of the liver by the body's circulatory system. It can be either a congenital or acquired condition.
 * A portacaval shunt / portal caval shunt is a treatment for high blood pressure in the liver.