Thoracic Aortic Aneurysm and Dissection

The aorta is the largest artery in your body, and it carries blood away from your heart to all the parts of your body. The part of your aorta that runs through your chest is called the thoracic aorta and, when your aorta reaches your abdomen, it is called the abdominal aorta. When a weak area of your thoracic aorta expands or bulges, it is called a thoracic aortic aneurysm (TAA). Approximately 25 percent of aortic aneurysms occur in the chest, and the rest involve the abdominal aorta.

A special type of thoracic aneurysm is called an aortic dissection, and is usually associated with high blood pressure. Sometimes, blood flow forces the layers of the wall of your aorta apart, and it weakens your aorta and can cause TAA. The separation can extend from your thoracic aorta through your entire aorta and block arteries to your legs, arms, kidneys, brain, spinal cord, and other areas. Another problem associated with aortic dissection is that over time, the pressure of blood flow can cause the weakened area of your aorta to bulge like a balloon. Much like an over-inflated balloon, an aneurysm can stretch the aorta beyond its safety margin.

Thoracic aortic aneurysms are a serious health risk because they can burst or rupture. A ruptured aneurysm can cause severe internal bleeding, which can lead to shock or death.

Thoracic aneurysms affect approximately 1500 - 2000 people in the Australia each year. Some patients may have more than one TAA or may also have an aneurysm in the abdominal aorta. Only about 20 to 30 percent of patients who get to the hospital with a ruptured TAA survive. For this reason, it is crucial to treat large aneurysms early in order to prevent their rupture.

What are the symptoms?

You may not feel any symptoms with TAA. Only half of patients with TAA notice symptoms.

Your symptoms will depend on where your aneurysm is located, whether it is an aortic dissection or not, and how large it is. Possible symptoms include:

  • Pain in the jaw, neck, and upper back
  • Chest or back pain
  • Coughing, hoarseness, or difficulty breathing

If your aneurysm is large, it may affect your heart valves and lead to a condition called congestive heart failure.

The symptoms of aortic dissection can occur suddenly and severely. For example, you may feel a sharp, tearing pain in your chest or upper back, Acute breathlessnes. You may not notice any symptoms, however.

It is critical to notify your physician immediately if you experience any symptoms of TAA or aortic dissection. If left untreated, these conditions may lead to a fatal rupture. This is a life-threatening situation and you should seek medical attention immediately.

What causes a thoracic aortic aneurysm?

Researchers believe that atherosclerosis, also called hardening of the arteries, causes TAA. Your arteries are normally smooth and unobstructed on the inside but, as you age, they can become blocked through a process called atherosclerosis, which means hardening of the arteries. In atherosclerosis, a sticky substance called plaque builds up in the walls of your arteries. Over time, your arteries narrow, stiffen, and possibly weaken. Factors that increase your risk for atherosclerosis include:

  • Smoking
  • High blood pressure
  • High cholesterol
  • Obesity
  • Having a family history of heart disease

Certain diseases can weaken the layers of the aortic wall, increasing the risk of aneurysms. These diseases include:

  • Marfan's syndrome, a connective tissue disorder
  • Syphilis
  • Tuberculosis

Rarely, trauma, such as a fall or rapid deceleration, may cause TAA.

Your risk of developing TAA increases as you age. TAA is more common in men than in women. The larger your TAA, or the faster it grows, the more likely it is to rupture. The chance of rupture increases when your aneurysm is larger than about twice the normal diameter.

What tests will I need?

Your physician will order one or more of the following tests to diagnose TAA:

  • Chest x ray
  • Echocardiography (an ultrasound of the heart)
  • Magnetic resonance imaging (MRI)
  • Computed tomography (CTA) scan
  • Angiography
  • How is a thoracic aortic aneurysm treated?

"Watchful Waiting"

If your TAA is small and not causing symptoms, your physician may recommend "watchful waiting,” which means that you will be monitored every 12 months for signs of changes in your aneurysm. Your physician may schedule you for CTA or MRI scans every 12 months to watch the aneurysm. CT scans take x-ray pictures of slices of your body. This test can help your physician monitor the size of your aneurysm. This method is usually used for aneurysms that are smaller than about 2 inches across. If you also have high blood pressure, your physician may prescribe blood pressure medication to lower your overall blood pressure and the pressure on the weakened area of the aneurysm.

However, if your TAA is large or causing symptoms, you need active and prompt treatment to prevent rupture. Your vascular surgeon may recommend actively treating your aneurysm if it is large, grows quickly, or you have other types of disease. For example, if you have Marfan's syndrome, you may require active treatment sooner than patients who have small TAAs but do not have Marfan's syndrome. The active treatments for TAA are open aneurysm repair and endovascular stent-graft repair.

Open Surgical Repair

During open aneurysm repair, your surgeon makes an incision in your chest and replaces the weakened portion of your aorta with a fabric tube, called a graft. The graft is stronger than the weakened aorta and allows blood to pass through it without causing a bulge. Many patients who have a TAA also have heart disease or involvement of the aorta adjacent to the heart. For Extensive or complex thoracic aneurysms, sometimes heart surgery is performed at the same time as open aneurysm repair depending upon the particular situation.

Following the surgery, you usually stay in the hospital for 5 to 7 days. If your aneurysm is extensive or complex, or if you have other conditions such as heart, lung or kidney disease, you may require 2 to 3 months for a complete recovery.

Endovascular Stent graft repair

Instead of open aneurysm repair, your vascular surgeon may consider a promising, newer procedure called an endovascular stent graft. Endovascular means that the treatment is performed inside your body using long, thin tubes called catheters. The catheters are inserted in small incisions in your groin and are guided through your blood vessels. During the procedure, your surgeon will use live x-ray pictures viewed on a video screen to guide a stent-graft to the site of your aneurysm. Like the graft used in open surgery, this stent-graft allows blood to flow through your aorta without putting pressure on the damaged wall of your aneurysm. This keeps your aneurysm from rupturing. Over time, your aneurysm will shrink. Endovascular stent-graft repair requires a shorter recovery time than open aneurysm repair, and your hospital stay is reduced to 2 of 3 days.

This treatment is now available in Newcastle and Hunter area and has proved to highly successful. However, your aneurysm must have a suitable shape to allow the stent-graft to be used effectively. With the endovascular stent-graft repair, it is particularly important that long-term follow-up with periodic scans of the aortic repair be done to be sure that the stent-graft is functioning properly. Sometimes further procedures are required to maintain the stent-graft if leaks develop or if it moves out of position. The long-term results of endovascular stent-graft repair are being closely monitored: current reports and local results have shown that this treatment is highly successful.

After you have had appropriate investigations, Dr Bray will advise you regarding the best option for your particular situation.