In medicine, a<unk> 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<unk> ; and acquired<unk>  (sometimes referred to as iatrogenic<unk>  may be either biological or mechanical.
Cardiac<unk>  may be described as right-to-left, left-to-right or bidirectional, or as systemic-to-pulmonary or pulmonary-to-systemic.
Cerebral<unk>  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<unk>  exist when there is normal perfusion to an alveolus, but ventilation fails to supply the perfused region.
A portosystemic<unk> (PSS), also known as a liver<unk>  is a bypass of the liver by the body's circulatory system.  It can be either a congenital or acquired condition.
A portacaval<unk> / portal caval<unk> is a treatment for high blood pressure in the liver.
Shunt 
Brain zap
Dentures
Tracheal deviation
Splenosis
Barrel chest
Malocclusion
Stridor