The human aorta is the longest and largest artery in the body that arises from the left ventricle of the heart (aortic root), runs straight up (ascending aorta), bends over (aortic arch) and then runs down through the chest (descending thoracic aorta) and the abdomen (abdominal aorta) where it divides (aortic bifurcation) to run in to the legs.
The Aorta carries oxygen-rich blood away from the heart to vessels that reach the head, neck, arms, legs and vital organs in the chest and abdomen (Figure 1). The aortic wall has three layers that are comprised of smooth muscle and elastic fibres.
AORTIC DISEASE (AORTOPATHIES)
In certain abnormal circumstances, the human aorta can enlarge, dissect, rupture, develop atherosclerosis or become infected. Such aortic abnormalities are termed as aortopathies.
Genetic aortic disease occurs due to mutations in specific genes that get passed on from one generation to the next; termed as heritable or familial aortic disease. In older people, hypertension and cigarette smoking are risk factors for aortopathy. Inflammation, infection and atherosclerosis are the most common ‘acquired’ causes of aortopathy. However, these causes could have genetic or familial predispositions.
Aortic dilation is an enlargement of the aorta. Enlargement of the aorta can cause the aortic valves to not fully close leading to back-flow of the blood from the aorta into the heart, which is referred to as Aortic Regurgitation. This situation may cause forceful heartbeats and shortness of breath during normal light activity.
When the dilation is beyond an arbitrary size (varies depending on the gene mutation and other factors), leading to a bulge in the aortic wall, it is termed an Aortic Aneurysm.
Depending on the location, aortic aneurysms are thoracic or abdominal. Thoracic aortic aneurysms are those located above the diaphragm and may involve the aortic root, ascending aorta, aortic arch or the descending aorta.
Abdominal aortic aneurysms are those located under the diaphragm. Most abdominal aortic aneurysms occur between the renal arteries and the aortic bifurcation.
When the aorta enlarges and stretches it becomes prone to an Aortic Dissection (a tear within the layers of the aortic walls) and could potentially rupture.
There are two types of aortic dissection:
1) Dissection of the ascending aorta (Type A): the part of the blood vessel closest to the heart, usually the first two inches of the aorta from the heart; including the aortic root and sections of the ascending aorta. It is life-threatening and requires immediate surgery.
2) Dissection of the descending aorta (Type B): the part of the aorta that comes down after the aortic arch into the chest cavity and below the waist. Dissection of the descending aorta is usually managed with medication and regular monitoring. Surgery is needed only in serious complications in which there is loss of blood flow to vital organs or an extremely enlarged aorta.
Aortic dissections and/or aneurysms may present with one or more of the following symptoms. However, some patients have confessed that they did not have any symptoms before or at the time of a dissection.
- severe, sharp pain in the chest, back or abdomen
- pain in the jaw and neck radiating into arms and head
- sudden pain in the throat
- difficulty breathing or speaking
- dizziness and/or nausea
- weak or unusual blood pressure
- loss of consciousness
- weakness of limbs
- vision disturbances
- other symptoms similar to a stroke or heart attack