Robert Wood Johnson University Hospital
 

Thoracic Aortic Aneurysm

Thoracic Aortic Aneurysm and Aortic Dissection

What is a thoracic aortic aneurysm?

Illustration of the anatomy of the aorta
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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 vessel's 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.

What are the different 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.

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). 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.
  • 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. This is hardening of the arteries caused by a buildup 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 a thoracic aneurysm may include, but are not limited to, the following:

The symptoms of a thoracic aortic aneurysm may resemble other conditions. Consult your doctor 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:

What is the treatment for thoracic aortic aneurysm?

Specific treatment will be determined by your doctor based on:

Treatment may include:

A small aneurysm or one that doesn't cause symptoms may not require surgical treatment until it reaches a certain size or is rapidly increasing in size over a short period of time. Your doctor may recommend "watchful waiting." This may include a CT scan or MRI scan every six months to closely monitor the aneurysm, and blood pressure medication may be used to control high blood pressure.

If the aneurysm is causing symptoms or is large, surgery may be recommended by your doctor.

What is aortic dissection?

An aortic dissection, although uncommon, begins with a tear in the inner layer of the aortic wall of the thoracic aorta. The aortic wall is made up of three layers of tissue. When a tear occurs in the innermost layer of the aortic wall, blood is then channeled into the wall of the aorta separating the layers of tissues. This generates a weakening in the aortic wall with a potential for rupture. Aortic dissection can be a life-threatening emergency.

Illustration of aortic dissection
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What causes aortic dissection?

The cause of aortic dissection is still under investigation. However, there are several risk factors associated with aortic dissection, such as:

What are the symptoms of aortic dissection?

The most commonly reported symptom of an acute aortic dissection is severe, constant chest and/or upper back pain, sometimes described as "ripping" or "tearing." The pain may be "migratory," moving from one place to another, according to the direction and extent of the dissection.

How is aortic dissection diagnosed?

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

The doctor will determine the most appropriate examination. When a diagnosis of aortic dissection is confirmed, immediate intervention, such as surgery, is usually performed.

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