Abdominal Aortic Aneurysm (AAA)

• What is an abdominal aortic aneurysm?
• What are the symptoms of an abdominal aortic aneurysm?
• What causes an abdominal aortic aneurysm?
• How is an AAA treated?

What is an abdominal aortic aneurysm?
Each year in the United States, approximately 200,000 people will be diagnosed with an abdominal aortic aneurysm. The aorta is the large blood vessel that carries blood from the heart to the rest of the body. An aneurysm is a localized bulging of the aorta, which weakens the wall of the aorta and can lead to rupture. Rupture or bursting of an abdominal aortic aneurysm is usually fatal. Therefore, when aneurysms reach a certain size, repair of the aneurysm is needed to prevent it from growing bigger and eventually rupturing.

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What are the symptoms of an abdominal aortic aneurysm?
Most people who have AAA do not have symptoms. For this reason, AAA is often called a "silent killer". When aneurysms become larger, they may cause a sensation of pulsation or throbbing in a person's abdomen, or pain or tenderness in the abdomen or lower back. When rupture of an aneurysm develops, this can cause sudden extreme pain in the abdomen or back, relieved somewhat by sitting forward, with signs of shock (dizziness, fainting, weakness). This represents a life-threatening emergency.

Because AAA does not cause symptoms in most people, AAA is often diagnosed during a routine medical examination. A physician may be able to feel an area of pulsation or bulging in the lower abdomen. Aneurysms may also be diagnosed from pictures performed during a CAT scan, ultrasound or MRI scan.

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What causes an abdominal aortic aneurysm?
Weakening of the wall of the aorta leading to a bulging out or ballooning of the artery is still not well understood. To some extent, AAA can be hereditary however it yet no gene has been identified. People with hardening of the arteries (atherosclerosis), high blood pressure, smoking and heart disease are at higher risk of developing an aneurysm. Males are four times more likely to have AAA than females.

In people who have been found to have AAA, controlling blood pressure, stopping smoking, and maintaining normal cholesterol are important lifestyle changes, which may help to prevent future problems including enlargement and rupture.

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How is an AAA treated?
When an AAA is small, it needs to be monitored with periodic scans (such as a CAT scan, ultrasound or MRI scan) to make sure that the aneurysm does not enlarge or expand to a size that is at high risk for rupture. When an aneurysm reaches a large size, in most patients repair of the aneurysm is necessary. At present, this size is considered to be 5 centimeters across, which is about 2 inches wide.

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Open Surgical Repair
In the past, repair of an AAA required open surgery, where a surgeon makes a large incision in the abdomen or in the side of the person. The surgeon then places a clamp around the aorta and cuts open the aneurysm. The surgeon repairs the aorta by sewing a piece of synthetic tubing (a graft) inside the aorta using sutures. This operation diverts blood from the diseased part of the aorta through the graft material. This is a major surgical procedure requiring general anesthesia and takes several hours to perform.

Typically patients remain in intensive care for 1-2 days after the procedure and remain in the hospital for another week. Recovery can vary from person to person but generally takes several months.

Because some patients cannot safely undergo open surgical repair of an abdominal aortic aneurysm, the last decade has seen the emergence of a new alterative for repairing abdominal aortic aneurysm. This is known as endovascular repair.

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Endovascular Repair
This less invasive alterative to open repair of an AAA involves sealing off the aneurysm by placing a special device inside the aorta, and is performed by an interventionalist. The device is similar to the synthetic piece of tubing that is sewn into place during an open repair of an aneurysm. Instead, this tubing is supported inside the aorta by a scaffolding system known a stent. Together, the device is called an endo-graft (endo meaning "inside").

The endograft is positioned inside the aorta by inserting it through a system of special tubes and catheters, which are inserted through a patient's groin arteries. Endovascular repair may be performed under general, regional or local anesthesia and typically takes 1-3 hours to perform. Patients are usually in the hospital for several days and can resume normal activity within a few weeks of the procedure.

Endovascular repair of abdominal aortic aneurysms usually requires that surgical incisions be made over both groin areas. Through these incisions, the femoral arteries are exposed. The arteries are then cut open to allow insertion of the special tubes that are needed to insert the endovascular grafts. Following repair of the aneurysm, the groin arteries are closed with sutures. The groin incisions are closed with sutures and/or staples. The staples may then be removed after the groin incisions have healed.

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Percutaneous Endovascular Repair
More recently a minimally invasive alternative has become available at several leading medical centers in Europe and the United States. This is called percutaneous (meaning "through the skin") endovascular repair.

This consists of inserting the tubes and catheters needed for endovascular repair through tiny skin nicks over the groin arteries. No large incisions are made. Instead, a microsurgical device is used to insert sutures through the opening into the arteries using the same opening into the artery made for inserting the endograft system. After the aneurysm has been repaired, the openings in the arteries are sealed shut by tying the sutures. In addition to being less invasive than conventional endovascular repair, in some patients this minimally invasive form of endovascular repair may have a lower risk of groin complications.

It is important to recognize that not every patient will be a candidate for endovascular repair and not every patient will be a candidate for percutaneous endovascular repair. People whose groin arteries are too small or diseased with plaque or calcium may not be able to undergo percutaneous endovascular repair.

Percutaneous endovascular aortic aneurysm repair at the Hospital of the University of Pennsylvania is performed by highly trained interventional radiologists in the division of Interventional Radiology. If you have been diagnosed as having an abdominal aortic aneurysm, you are welcome to schedule a consultation with one of our specialists who can determine if you are a candidate for endovascular repair or percutaneous endovascular repair.

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A male patient with AAA. Notice the bulging area of the aorta (arrows).

The patient underwent percutaneous endovascular repair of the AAA at the Hospital of the University of Pennsylvania. An endograft stent has been inserted inside the aneurysm (arrows) through tiny skin nicks in the groin. The procedure took approximately 2 hours to perform.

Final view of the endograft within the aorta. Notice the blood flows through the endograft and not the aneurysm.

Reviewed by: Timothy Clark, MD
January 2005

References

1. Borner G, Ivancev K, Sonesson B, Lindblad B, Griffin D, Malina M. Percutaneous AAA Repair: Is It Safe? J Endovasc Ther. 2004 Dec;11(6):621-6.
2. Morasch MD, Kibbe MR, Evans ME, Meadows WS, Eskandari MK, Matsumura JS, Pearce WH. Percutaneous repair of abdominal aortic aneurysm. J Vasc Surg. 2004 Jul;40(1):12-6.
3. Teh LG, Sieunarine K, van Schie G, Goodman MA, Lawrence-Brown M, Prendergast FJ, Hartley D. Use of the percutaneous vascular surgery device for closure of femoral access sites during endovascular aneurysm repair: lessons from our experience. Eur J Vasc Endovasc Surg. 2001 Nov;22(5):418-23.
4. Howell M, Doughtery K, Strickman N, Krajcer Z. Percutaneous repair of abdominal aortic aneurysms using the AneuRx stent graft and the percutaneous vascular surgery device. Catheter Cardiovasc Interv. 2002 Mar;55(3):281-7.
5. Torsello GB, Kasprzak B, Klenk E, Tessarek J, Osada N, Torsello GF. Endovascular suture versus cutdown for endovascular aneurysm repair: a prospective randomized pilot study. J Vasc Surg. 2003 Jul;38(1):78-82.
6. Society of Interventional Radiology Website, www.sirweb.org.

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