Aorta, coarctation of the: A constriction of the aorta. At the point of coarctation, the sides of the aorta appear to be pressed together. Blood pressure is increased above the constriction, and the flow of blood is impeded below the level of the constriction. Symptoms may not be evident at birth but can develop as soon as the first week after birth, with congestive heart failure or high blood pressure that call for early surgery. The outlook after surgery is usually favorable. Some cases of coarctation of the aorta have been treated with balloon angioplasty.