Final answer:
An aortic dissection is the separation of the aorta walls due to an intimal tear, forming a false lumen and sometimes a "reentry" tear, leading to a "double barrel" aorta. It typically requires emergency medical treatment and is different from congenital narrowings, such as coarctation of the aorta.
Step-by-step explanation:
The separation of the walls of the aorta from an intimal tear and disease of the tunica media that forms a false lumen and potentially a "reentry" tear, resulting in a "double barrel" aorta, is known as an aortic dissection. This serious condition occurs when the inner layer of the aorta tears, allowing blood to flow between the layers of the wall of the aorta and causing them to separate, or dissect. The internal elastic membrane plays a role in maintaining the structural integrity of the aorta's layers by separating the tunica intima from the tunica media, and its failure can contribute to such vascular emergencies.
Unlike coarctation of the aorta, which is a congenital abnormal narrowing of the aorta, an aortic dissection is generally an acute condition that requires emergency medical attention. A coarctation, however, leads to restricted blood flow and can be life-threatening if severe but may remain undiagnosed until later in life if benign. Both conditions highlight the significance of the aorta's anatomical and functional integrity for cardiovascular health.