Abdominal Aortic Aneurysms The aorta is the main blood vessel leading from the heart to the body. The abdominal aorta supplies blood to the lower half of the body.

An abdominal aortic aneurysm (AAA) is a weakening and bulging in the wall of the abdominal aorta. As blood flows through the vessel, the bulging area can become weaker. Like a bubble in a tire, the aneurysm can eventually break open, or rupture . This is a very serious complication that can quickly lead to death from bleeding.

According to the Society for Interventional Radiology, AAA affects about eight percent of people over 65. The condition is four times more common in men than in women. Risk factors include: high blood pressure, high cholesterol, obesity and a history of smoking.

Each year, about 15,000 Americans die from a ruptured AAA. It's the 17th leading cause of death in the U.S.

AAAs are often referred to as a silent killer because they usually don't cause symptoms until they rupture. Because of the potentially deadly consequences, health experts now recommend a one-time screening for AAA in men 65 to 75 who have ever smoked (current and former smokers).

Treating AAAs The goal of treatment for AAA is to prevent a rupture. Once the aneurysm bursts, a patient only has about a 10 to 20 percent chance of survival. Generally, the larger the aneurysm, the greater the likelihood of rupture. If the aneurysm is less than 5 centimeters (about two inches), doctors may prefer to watch and monitor the patient with occasional ultrasound examinations to monitor the status of the aneurysm. If the aneurysm starts growing, or grows at more than one centimeter a year, intervention may be necessary.

There are two main treatments for repairing AAAs. The standard fix is open surgery. An incision is made into the abdomen and the abdominal aorta is located. The aorta is temporarily clamped to stop the flow of blood. The area containing the aneurysm is cut open and a surgical graft (artificial tube) is sewn inside the vessel. Blood flows through the new tube, relieving pressure on the vessel wall.

The second treatment for AAA is an endovascular repair. Instead of an open incision, surgeons make a tiny incision into the femoral artery in the groin. Then a catheter with a special stent graft (tube patch and expandable meshwork) is fed through the circulatory system up to the area of the AAA. When the site is reached, a balloon is inflated to open the stent graft. Blood flows through the graft, which covers up and protects the fragile walls of the aneurysm.

The Fenestrated Stent Graft Patients who are very sick or have other medical complications may be unable to undergo open surgery and may need endovascular repair. But when an aneurysm is located too close to other major arteries that branch off the aorta (like those feeding the kidneys), endovascular repair could potentially block the affected arteries.

Researchers at the University of Pennsylvania are testing a new type of stent, called the Zenith® Fenestrated AAA Endovascular Graft. The fenestrated stent is made from a woven polyester. The top section of the graft is the designed with special scallops or openings. The scallops allow designers to custom-fit the stent to the patient's specific anatomical needs.

To tailor the stent graft, doctors use CT scans to map the precise location of the branching arteries. The information is given to design engineers who custom-make the stent graft.

The fenestrated graft is placed like a traditional endovascular stent graft. Using X-rays for guidance, the surgeon feeds the stent up to the AAA. The trunk of the device stays in the aorta and the custom-designed branches are plugged into the branching arteries. The stent is expanded, opening up the graft inside the aorta and branching arteries. Blood flows through the new graft without blocking critical flow to the kidneys.

The Zenith Fenestrated AAA Endovascular Graft is currently being tested in clinical trials.

For information about the fenestrated stent: http://www.zenithstentgraft.com, or http://www.cookgroup.com/news/010705.html

For information about abdominal aortic aneurysms: American Heart Association, http://www.americanheart.org Society of Interventional Radiology, http://www.sirweb.org

The Society of Thoracic Surgeons, http://www.sts.org