Coarctation of the aoa is a congenital condition whereby the aoa is narrow, usually in the area where the ductus aerioses inses. The word "coarctation" means narrowing. Coarctations are most common in the aoic arch. The arch may be small in babies with coarctations. Other hea defects may also occur when coarctation is present, typically occurring on the left side of the hea. When a patient has a coarctation, the left ventricle has to work harder. Since the aoa is narrowed, the left ventricle must generate a much higher pressure than normal in order to force enough blood through the aoa to deliver blood to the lower pa of the body. Ref - researchgate.net