Thoracic Aortic Aneurysm

Illustration of the anatomy of the aorta

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What is a thoracic aortic aneurysm?

A thoracic aortic aneurysm, also called TAA, is a bulging, weakened area in the wall of the aorta (the largest artery in the body), resulting in an abnormal widening or ballooning greater than 50 percent of the normal diameter (width).

The aorta extends upward from the top of the left ventricle of the heart in the chest area (ascending thoracic aorta), then curves like a candy cane (aortic arch) downward through the chest area (descending thoracic aorta) into the abdomen (abdominal aorta). The aorta delivers oxygenated blood pumped from the heart to the rest of the body.

An aneurysm can be characterized by its location, shape, and cause. A thoracic aortic aneurysm is located in the chest area. The thoracic aorta can be divided into segments: ascending aorta, aortic arch, and descending aorta, as described above. An aneurysm may be located in one of these areas and/or may be continuous throughout the aorta. An aneurysm called a thoracoabdominal aneurysm involves a thoracic aortic aneurysm extending down to the abdominal aorta.

Illustration of thoracic aortic aneurysm

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Thoracic aneurysms do not occur as often as abdominal aneurysms. The descending thoracic aorta is the most common location of a thoracic aneurysm, followed by the ascending segment, then the arch. The location of an aneurysm is distinctly connected with the cause, course, and treatment of a thoracic aneurysm.

Types of thoracic aortic aneurysms:

The shape of an aneurysm is described as being fusiform or saccular which helps to identify a true aneurysm. A true aneurysm involves all three layers of the arterial blood vessel wall. The more common fusiform-shaped aneurysm bulges or balloons out on all sides of the aorta. A saccular-shaped aneurysm bulges or balloons out only on one side.

A pseudoaneurysm, or false aneurysm, is an enlargement of only the outer layer of the blood vessel wall. A false aneurysm may be the result of prior surgery or trauma. Sometimes, a tear may occur on the inside layer of the vessel resulting in blood entering the layers of the blood vessel wall, creating a pseudoaneurysm.

Illustration of types of aneurysms

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The aorta is under constant pressure from blood being ejected from the heart. With each heartbeat, the walls of the aorta expand and spring back, exerting continual pressure or stress on the already weakened aneurysm wall. Therefore, there is a potential for rupture (bursting) or dissection (separation of the layers of the thoracic aortic wall), which may cause life-threatening hemorrhage (uncontrolled bleeding) and, potentially, death.

Once formed, an aneurysm will gradually increase in size and there will be a progressive weakening of the aneurysm wall. Treatment for a thoracic aneurysm may include surgical repair or removal of the aneurysm to prevent rupture.

What causes a thoracic aortic aneurysm to form?

Thoracic aortic aneurysms may be caused by different disease processes, especially in respect to their location.

Examples of different locations of thoracic aortic aneurysms and their causes may include, but are not limited to, the following:

Location of Thoracic Aortic Aneurysm Causes Associated with Aneurysm Type
Ascending Thoracic Aneurysm
  • Cystic medial degeneration (necrosis) - Breaking down of the tissue of the aortic wall. This is the most common cause of this type of thoracic aortic aneurysm.
  • Genetic disorders which affect the connective tissue, such as Marfan syndrome and Ehlers-Danlos syndrome
  • Family history of thoracic aortic aneurysm with no incidence of Marfan syndrome
  • Atherosclerosis - Hardening of the arteries caused by a build-up of plaque in the inner lining of an artery. This is a rare cause of ascending thoracic aortic aneurysm.
  • Infection, syphilis (rare causes of thoracic aortic aneurysm)
Aortic Arch Thoracic Aneurysm
  • Takayasu's arteritis - A type of vasculitis that causes inflammation of the arteries
  • Atherosclerosis
  • Continuation of an ascending and/or descending aortic aneurysm
Descending Thoracic Aortic Aneurysm Atherosclerosis is most often associated with descending thoracic aneurysms, and is thought to play an important role in aneurysmal disease, including the risk factors associated with atherosclerosis such as:
  • Age (greater than 55)
  • Male gender
  • Family history (first-degree relatives such as father or brother)
  • Genetic factors
  • Hyperlipidemia (elevated fats in the blood)
  • Hypertension (high blood pressure)
  • Smoking
  • Diabetes

What are the symptoms of a thoracic aortic aneurysm?

Thoracic aortic aneurysms may be asymptomatic (without symptoms) or symptomatic (with symptoms). Symptoms of a thoracic aneurysm may be related to the location, size, and growth rate of the aneurysm.

Severe onset of pain associated with a thoracic aneurysm may be a sign of a life-threatening medical emergency.

Symptoms of an ascending thoracic aneurysm may include, but are not limited to, the following:

Symptoms of an aortic arch aneurysm or a descending thoracic aneurysm may include, but are not limited to, the following:

The symptoms of a thoracic aortic aneurysm may resemble other conditions. Consult your physician for a diagnosis.

How is a thoracic aortic aneurysm diagnosed?

In addition to a complete medical history and physical examination, diagnostic procedures for a thoracic aortic aneurysm may include any, or a combination, of the following:

Treatment for thoracic aortic aneurysm:

Specific treatment will be determined by your physician based on:

Treatment may include:

Asymptomatic aneurysms may not require surgical intervention until they reach a certain size or are noted to be increasing in size over a certain period of time. Parameters considered when making surgical decisions include, but are not limited to, the following:

For symptomatic aneurysms, immediate intervention is indicated.

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