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Stent Graft Repair of Abdominal Aortic Aneurysms
An aortic aneurysm is a weak area in the aorta, the main blood vessel that carries blood from the heart to the rest of the body. As blood flows through the aorta, the weak area bulges like a balloon and can burst if the balloon gets too big. A small aneurysm may require no immediate treatment other than "watchful waiting" - checking the aneurysm regularly to be certain it does not grow. If an aneurysm reaches a certain size, however, there is a danger that it will burst and bleed uncontrollably (hemorrhage). In these cases treatment is necessary.
The following information was prepared by the Society of Cardiovascular & Interventional Radiology (SCVIR) to provide general information about abdominal aortic aneurysm - the most common type of aortic aneurysm. This site reviews the signs and symptoms, how it is diagnosed, and when it may require treatment. Treatment of an abdominal aortic aneurysm may require surgery. For some patients, however, a new, non-surgical treatment called "stent-graft repair" can be performed by an interventional radiologist. This site gives an overview of treatment options, and specific information about stent-graft repair, the new, interventional radiology treatment that does not require surgery.
Q: What is an aneurysm?
An aneurysm is a weak area in the wall of a blood vessel that bulges like a balloon when blood flows through the vessel. Aneurysms can occur throughout the body, and sometimes they are harmless. But sometimes they are life-threatening. Aneurysm occurs most commonly in the brain (cerebral aneurysm) or the aorta, the main blood vessel that supplies blood to the body. An aortic aneurysm may be in the chest cavity (thoracic aortic aneurysm), but it is most commonly seen in the abdomen (abdominal aortic aneurysm).
Q: What is an abdominal aortic aneurysm (AAA)?
An abdominal aortic aneurysm (AAA) is a weak area in the wall of the abdominal aorta - the artery that carries blood from the heart to the rest of the body. The aorta is the body’s largest blood vessel; when an area is weak, it may bulge like a balloon when blood flows through it. The most common site for an aortic aneurysm to occur is below where the aorta divides to supply blood to the kidneys and above where it divides to supply blood to the pelvis and legs. An aneurysm that occurs in this location is called an abdominal aortic aneurysm. The normal diameter of the aorta is about 1 inch or less. Small aneurysms - less than 2 inches (5 centimeters) rarely rupture and may pose little risk to the patient. If the aneurysm grows larger, however, the risk of rupture and life-threatening bleeding (hemorrhage) increases. In most cases, physicians recommend treating aneurysms that are 5.5 centimeters or greater in diameter.
Q: How Common is AAA?
Abdominal aortic aneurysms occur in from 5 percent to 7 percent of people over the age of 60 in the United States. Males are at least four times more likely to have AAA than females, and some studies have shown the rate in males to be even higher. According to one study, the incidence of AAA has increased three-fold over the past 40 years, making it the 13th leading cause of death in the U.S. The condition accounts for nearly 15,000 deaths each year.
Approximately one in every 250 people over the age of 50 will die of a ruptured AAA. Fortunately, when AAA is diagnosed early it can be successfully treated and rupture is prevented. Depending on the individual, treatment may require surgery. Often, however, the aneurysm can be repaired with a new,interventional radiology technique that does not require open surgery.
Q: What are the symptoms of AAA?
AAA is often a silent disease. Many patients do not experience any symptoms, particularly when the aneurysm is small. If there are symptoms, the most common ones are:
- intense abdominal pain that may be constant or come and go.
- pain in the lower back that may radiate to the buttocks, groin or legs
- the feeling of a "heart beat" or pulse in the abdomen.
- Fatigue
- Sometimes, the aneurysm can be felt as a soft mass in the abdomen.
If an aneurysm expands rapidly, tears open, or bursts, or if blood leaks along the wall of the blood vessel (aortic dissection), more severe symptoms may develop suddenly. A ruptured aneurysm is life-threatening and requires immediate emergency care.
Symptoms of a ruptured aneurysm may include:
- severe pain that begins suddenly
- paleness
- rapid pulse
- dry mouth/skin and excessive thirst
- anxiety
- nausea and vomiting
- lightheadedness or fainting
- excessive sweating or clammy skin
- shock
Q: Who is at Risk for AAA?
The most common cause of an aortic aneurysm is atherosclerosis (often called "hardening of the arteries"). Atherosclerosis is a gradual process in which cholesterol and scar tissue build up, forming a substance called "plaque" that weakens or damages the walls of the blood vessels and makes them more vulnerable to an aneurysm. Other risk factors are high blood pressure, smoking and a family history of AAA. Less frequently, aneurysms may be caused by connective tissue diseases, inflammation of the blood vessels (vasculitis) and some congenital disorders. Aortic aneurysms most frequently occur in white males between the agesof 50 and 60.
Q: How do I know if I have an AAA?
A careful physical examination can detect as many as 70 percent to 80 percent of abdominal aortic aneurysms. By placing a stethoscope on the abdomen, the doctor often can hear the sounds of abnormal blood flow through the roughened surface of the aorta. The doctor also may be able to feel the aneurysm by pressing gently on the abdomen. If your physician suspects that you have an AAA, further diagnostic tests will be performed.
Q: How is AAA diagnosed?
There are a number of imaging exams that can be used to "see" and diagnose an abdominal aortic aneurysm. Your doctor may recommend one or more of the following tests:
- An X-ray of the abdomen
- An ultrasound exam
- Magnetic resonance imaging (MRI)
- Computed tomography (CT or "CAT" scan)
Once an aneurysm has been diagnosed, the treatment will depend on a number of factors, such as the size of the aneurysm and the overall health of the patient. Small aneurysms of less than 2 inches (5 centimeters) in diameter rarely rupture and may pose little risk. If the aneurysm grows to 5.5 centimeters or larger, however, physicians usually recommend treating them with surgery or with non-surgical stent-graft repair.
Watchful Waiting
If the aneurysm is small and there are no symptoms, the doctor may recommend "watchful waiting." Periodic check-ups will be performed to watch for changes.
Treatment with Medication
If the aneurysm is small but there are symptoms, treatment may be required to prevent complications. Medication may be prescribed to lower blood pressure, or to relieve pain.
Surgical Repair
When an aneurysm reaches a certain size (about 2.2 inches or 5.5 centimeters) there is a danger that it will rupture. The traditional treatment has been to operate. A surgical incision is made in the abdomen. The surgeon cuts out the damaged part of the aorta and sews a synthetic (Dacron) tube in its place. Recovery from the operation, which is performed under general anesthesia, typically requires 8 to 10 days. People who have other serious medical problems may be poor risks for surgery.
Minimally Invasive Stent-Graft Repair
In recent years, interventional radiologist (IR) have developed a treatment to repair an aneurysm without surgery. An incision is made in the patient’s groin and a catheter (small tube ) is inserted into a blood vessel that leads to the aorta. A stent-graft (a Dacron tube inside a metal cylinder) is inserted through the catheter. Watching the progress of the catheter on an X-ray monitor, the interventional radiologist threads the stent-graft to the weak part of the aorta where the aneurysm is located. With this technique, there is no need to make a large incision in the abdomen or to cut away the damaged section of blood vessel. Once the stent-graft is in place, the metal cylinder is expanded like a spring to hold tightly against the wall of the blood vessel. The blood will now flow through the stent-graft, avoiding the aneurysm, which typically shrinks
Comparison with Surgery
According to a national study conducted at medical centers throughout the United States, interventional radiology stent-graft repair of abdominal aortic aneurysms has fewer complications than surgery, and allows people to be back on their feet in less time. Less days in the hospital are spent with stent-graft repair of an AAA compared to open surgical treatment. Patients undergoing stent-graft repair also experienced less blood loss and fewer (or no) days in the intensive care unit. Their average recovery time was 11 days, compared to 47 days with surgical repair.
Q: Which Treatment is Right for Me? The best treatment for an abdominal aortic ane
urysm (AAA) depends on a number of factors, including the size and location of the aneurysm, whether or not it is causing symptoms, and the age and general health of the patient. You should discuss all of these factors and any other questions you have with your primary care physician. You also may want to consult with an interventional radiologist to determine if you are a candidate for the non-surgical stent-graft repair procedure.
Q: How Are Other Types of Aneurysms Treated?
Currently, most thoracic aortic aneurysms are treated surgically. New research, however, shows that interventional radiology stent-graft treatment may also be appropriate for some patients with thoracic aneurysm. There are also interventional radiology treatments available for cerebral aneurysm. The best treatment for an aneurysm depends on a number of factors, including the size and location of the aneurysm, whether or not it is causing symptoms, and the age and general health of the patient. You should discuss all of these factors and any other questions you have with your primary care physician. You also may want to consult with an interventional radiologist to determine if you are a candidate for the non-surgical stent-graft repair procedure.