Coarctation of the aorta (CoA or CoAo), also called aortic narrowing, is a congenital condition whereby the aorta is narrow, usually in the area where the ductus arteriosus (ligamentum arteriosum after regression) inserts. The word coarctation means "pressing or drawing together; narrowing". Coarctations are most common in the aortic arch. The arch may be small in babies with coarctations. Other heart defects may also occur when coarctation is present, typically occurring on the left side of the heart. When a patient has a coarctation, the left ventricle has to work harder. Since the aorta is narrowed, the left ventricle must generate a much higher pressure than normal in order to force enough blood through the aorta to deliver blood to the lower part of the body. If the narrowing is severe enough, the left ventricle may not be strong enough to push blood through the coarctation, thus resulting in a lack of blood to the lower half of the body. Physiologically its complete form is manifested as interrupted aortic arch. Classification
There are three types of aortic coarctations:
Preductal coarctation: The narrowing is proximal to the ductus arteriosus. Blood flow to the aorta that is distal to the narrowing is dependent on the ductus arteriosus; therefore severe coarctation can be life-threatening. Preductal coarctation results when an intracardiac anomaly during fetal life decreases blood flow through the left side of the heart, leading to hypoplastic development of the aorta. This is the type seen in approximately 5% of infants with Turner syndrome.
Structurally, pulp stones can be classified as true and false pulp stones. True pulp stones are made up of dentine that is lined by odontoblast. True pulp stones are quite rare. On the other hand, false pulp stones are made up of concentric layers of mineralised tissue around blood thrombi, collagen fibres, or dying and dead cells. Histopathology
Histologically, there are two types of stones: (1) stones with regular calcifications (2) stones with irregular calcifications. For regular calcification, the pulp stones are smooth, round or ovoid with concentric laminations. It is commonly found in the coronal pulp. As for irregular calcifications without laminations, pulp stones may have the shape of rods or leaves and the surface is rough. It is more common in the radicular pulp. Pulp stones with regular calcification grow in size by addition of collagen fibrils to their surface, whereas the irregular type of pulp stones are formed by calcification of pre-existing collagen fibres. Pulp stones may also form around epithelial cells such as remnants of Hertwigs epithelial root sheath. It is presumed that epithelial remnants are able to induce adjacent mesenchymal stem cells to differentiate into odontoblasts. Associations
A pilot study was done with patients with cardiovascular disease (CVD) and it shows increased incidence of pulp stones in teeth with patients with CVD compared to healthy patients without CVD. There are also researchers which suggest the link between pulpal calcification and carotid artery calcification, despite not having a strong proof  on this correlation.