Aortic Aneurysm
An aneurysm is an abnormal widening or bulging of an artery. It occurs when a weakened area in the wall of an artery stretches and bulges as blood is pumped through it. Sometimes part of the inner lining of the wall of the aorta can split. This is called a dissecting aneurysm or aortic dissection.
Very large aortic aneurysms that are bigger than 5 to 6 centimetres in diameter are at risk of rupture. Rupture of an aortic aneurysm is a medical emergency and carries a high risk of death. Surgery is required immediately.
The aorta is the largest artery in the body and carries oxygen-rich blood from the heart to the rest of the body. The section of the aorta that runs through the chest is called the thoracic aorta. The section of the aorta that runs through the abdomen is called the abdominal aorta.
Aortic aneurysms are not uncommon and can occur anywhere along the length of the aorta. They may be only a few millimetres wide or they can expand to six centimetres or more in diameter.
Blood clots can accumulate within an aneurysm and can travel to blood vessels that supply other organs of the body. If one of these blood vessels becomes blocked by the clot, the resultant lack of blood flow can damage the organ.
Aortic aneurysms most commonly occur in people aged between 50 and 70 years. Men are affected about three times more frequently than women are. Risk factors for developing aortic aneurysms include:
- Being a male aged over 60 years
- Atherosclerosis (a build up of fatty deposits in the arteries)
- High blood pressure
- Having an immediate family member who has had an aortic aneurysm.
- Smoking
- Congenital abnormalities (eg: Marfan’s syndrome)
- Diseases that can weaken the aorta wall (eg: Tuberculosis, Syphilis).
Symptoms will depend on the location, nature and size of the aneurysm. Sometimes no symptoms are present until the aneurysm is large and at risk of rupturing.
Approximately three-quarters of all aortic aneurysms occur in the abdominal aorta. Symptoms of abdominal aortic aneurysms (AAA's) can include:
- A deep, pulsating, boring pain in the abdomen
- Backache
- Coolness of, or pain in, the lower limbs
- Approximately one quarter of all aortic aneurysms occur in the thoracic aorta. Symptoms of thoracic aortic aneurysms (TAA’s) can include:
- Pain in the neck, jaw and upper back.
- Chest or back pain.
- Wheezing, hoarseness, coughing and difficulty breathing.
If an aortic aneurysm ruptures, sudden pain, dizziness or weakness may be felt. Loss of consciousness usually occurs.
Aortic aneurysms that do not produce any symptoms are often found incidentally during diagnostic tests or treatments for other medical conditions.
If an aortic aneurysm is suspected a complete medical history will be taken and a physical examination will be performed. A referral to a vascular surgeon may also be made at this stage. They will undertake further tests to confirm the diagnosis and pinpoint the location and size of the aneurysm. These may include one or more of the following:
- Computed tomography scan (CT scan).
- Magnetic resonance imaging (MRI).
- Ultrasound scanning.
- Chest x-ray.
- Echocardiography (a specialised ultrasound of the heart).
- Angiography – a dye test of the aorta during which x-ray pictures are taken.
The type of diagnostic test(s) recommended will depend on the location of the suspected aneurysm (ie: thoracic or abdominal).
Many factors are taken into account when deciding how to treat an aortic aneurysm. These include:
The size of the aneurysm – the greater the size, the greater the risk of rupture.
- The location of the aneurysm.
- The proximity to or involvement with any of the arteries that branch from the aorta.
- The person’s general state of health and the presence of other medical conditions.
The two main treatment approaches include watchful waiting and surgical repair.
Watchful waiting
If the aortic aneurysm is small and is not causing any symptoms, the surgeon may recommend a “wait and watch” approach. This involves careful monitoring of symptoms and regular scans (usually every six months) to check for changes in the aneurysm. This usually involves CT scanning, MRI or ultrasound scanning.
High blood pressure will be treated with medications during this time to reduce the pressure on the aneurysm. Other conditions such as high cholesterol may also be treated.
Lifestyle changes such as stopping smoking and achieving and maintaining a healthy body weight will also be recommended.
In some cases a watchful waiting approach taken when the risks of surgery may be deemed to outweigh the risks of monitoring the aneurysm, even though the aneurysm is large and is causing symptoms. This is often the case when co-existing medical conditions are present - particularly those affecting the heart, lungs or kidneys. Age is also a factor, as the risks of surgery increase with age.
Surgical Treatment
If the aneurysm is large or is causing symptoms, surgical repair of the aneurysm may be recommended. The type of surgical repair used will depend on the location, size and shape of the aneurysm. The two main surgical techniques used to treat both thoracic and abdominal aortic aneurysms are:
Open Surgical Repair:
During open surgical repair an incision is made and the aneurysm is located and exposed. The aorta is clamped to prevent bleeding and the aneurysm is then opened and repaired, often using a synthetic patch made of Dacron or Teflon.
If the aneurysm is near the heart, heart bypass will be required. Heart bypass is where the circulation is taken over by a bypass machine, so that repair of the aneurysm can take place. Repair of abdominal aortic aneurysms does not usually require heart bypass.
A one to two day stay in an intensive care unit is expected after surgery, followed by a five to 10 day stay in hospital. Complete recovery is usually achieved within two to three months.
Endovascular Stent Graft:
This technique involves inserting a specialised synthetic graft into the aneurysm via a tube inserted in an artery in the groin. Under x-ray guidance the graft is fed up into the aorta until it lies within the aneurysm. It is then expanded so that it snugly lines the inside of the aneurysm. This enables blood to flow through the aorta without putting pressure on the aneurysm.
This technique only requires a small incision in the groin and has the advantage of a shorter hospital stay and a much quicker recovery time.
The development of aortic aneurysms cannot be prevented and little can be done to reduce the risk of the aneurysm expanding or rupturing. It is important however to maintain a general state of good health. This includes not smoking, maintaining a healthy body weight and exercising regularly. Controlling existing conditions such as angina or high blood pressure is also important, as is regular monitoring of the aneurysm.
Anderson, K.N., Anderson, L.E. & Glanze, W.D. (eds.) (2006) Mosby’s medical, nursing, & allied health dictionary (6th ed.) St. Louis: Mosby-Year Book, In
Boon, N.A. and Fox, K.A.A. (1995) Diseases of the cardiovascular system. In C.R.W. Edwards, Bouchier, I.A.D. (1995) Davidson’s principles and practice of medicine (17th ed.) Edinburgh: Churchill Livingstone
De Bellis, D. (2006) Aortic Aneurysm. The Gale Enclyclopedia of Medicine. Third Edition. Jacqueline L. Longe, Editor. Farmington Mills, MI. Thompson Gale.
Last Reviewed – 13/08/07