Brain Shunt. A brain shunt is a narrow piece of tubing that is inserted into the brain in the fluid-filled ventricle. The tubing is then passed under the skin into another area of the body, most often into the abdomen.Occasionally, the shunt tubing can be placed into one of the chambers of the heart or the lining of the lungs. brain shunt is a narrow piece of tubing that is inserted into the brain in the fluid-filled ventricle.