A Thoracic aortic aneurysm (TAA) is a localized bulging of the upper part of the aorta, result of an aortic wall weakness. The aorta is the main blood vessel-artery (~2cm diameter) that carries blood from the heart to the rest of the body.
It extends upward from the top of the left chamber of the heart in the chest area (ascending thoracic aorta), then curves (aortic arch) downward through the chest area (descending thoracic aorta) into the abdomen (abdominal aorta).
The aorta eventually splits to the right and left iliac arteries to supply the legs. An aortic aneurysm can develop anywhere along the aorta and it is named depending on its location.
Thoracic aortic aneurysms involve the thoracic (chest) aorta and can be ascending thoracic aortic aneurysms, aortic arch aneurysms or descending thoracic aorta aneurysms.
If the abdominal aortic segment is also involved then this is a thoraco-abdominal aneurysm.
Thoracic aneurysms do not occur as often as abdominal aneurysms. The ascending thoracic aorta is the most common location of a thoracic aneurysm, followed by the descending segment, then the arch.
Thoracic aneurysms can vary in size and as they grow larger there is an increasing risk for rupture. Depending on the size and growth rate of your thoracic aortic aneurysm, treatment may vary from watchful waiting to emergency surgery. Ideally, surgery for a thoracic aortic aneurysm should be planned if necessary.
Small and slow-growing thoracic aortic aneurysms may not ever rupture, but large, fast-growing aneurysms may rupture.
Multiple factors have been related to the development of a thoracic aortic aneurysm and there is definitely a hereditary component.
Atherosclerosis (hardening of the arteries) is an important risk factor for the development of an aortic aneurysm, as it leads to a diseased weak aortic wall.
This is usually the result of smoking, high blood pressure (hypertension), high cholesterol (hypercholesterolemia) and/or aging (>60 years old).
Aortic aneurysms are more frequent in men and can develop even in the absence of atherosclerosis:
• Heredity (immediate relatives with an aortic aneurysm)
• Cystic medial degeneration (necrosis). This is the breaking down of the tissue of the aortic wall. This is the most common cause of this type of thoracic aortic aneurysm.
• Congenital defects, such as an inherited weakness in the blood vessel wall (connective tissue disorders): Marfan's syndrome, Ehlers-Danlos syndrome, Turner's syndrome and polycystic kidney disease
• Other congenital disorders: bicuspid aortic valve, coarctation of the aorta
• Infection (aortitis)