April 25, 2008

New system eases abdominal aortic aneurysm repair

Featured Image

Tom Naslund, M.D.

New system eases abdominal aortic aneurysm repair

Vanderbilt vascular surgeon Tom Naslund, M.D., is focused on fixation.

Specifically, he is studying a new technique for endograft fixation — the means of securing a stent graft to the aorta when repairing abdominal aortic aneurysms (AAA).

The abdominal aorta is the main blood vessel supplying blood to the abdomen, pelvis and legs. An aneurysm there grows slowly and silently over a period of years, and when it begins to balloon outward, the aortic wall weakens.

The stent graft is designed to seal tightly with the artery above and below the aneurysm. The graft allows the blood to pass through the artery without pushing on the protuberance.

When a surgeon repairs an AAA through open surgery, the graft is sutured to the aorta to hold it in place. Surgeons have been challenged to find a suitable alternative when they repair the AAA with a stent graft, a minimally invasive technique.

Early prototypes either use tiny hooks to hold the graft in place or they rely on friction. These methods can result in blood leaking around the graft and migration, where the graft slips and shifts position.

Vanderbilt is one of 20 sites studying the new Aptus endograft system, which incorporates tiny metals screws to fix the graft to the artery wall. The screws and graft are delivered via a catheter, and Naslund uses a special type of screwdriver to attach them.

The new system has been used on three patients with good results.

“If a patient is a candidate for the Aptus graft, which allows the graft to be fixed more securely to the aorta, he or she wants it.

It addresses the two most dreadful complications at the same time — leak around the graft and the migration,” said Naslund, associate professor of Surgery and chief of the Division of Vascular Surgery.

Patients are followed carefully with CT scan after surgery to check for complications.

The study is comparing the Aptus system to the other prototypes to check for safety and efficacy.

The Aptus system uses a smaller catheter delivery system than other fixation devices, which means that women, who tend to have narrow iliac arteries, stand to benefit greatly from this latest technology.

“Other products have too large a delivery system. This is the smallest one of all of them. It treats the same diameters as other grafts. It treats more challenging anatomy, and it fixes the graft more securely. In every way it has potential advantages,” Naslund said.

Oftentimes, a person with an AAA doesn't know it's there until it is discovered through an annual exam or a CT scan.

Men over 65 who smoke are at highest risk for developing an AAA, which carries a strong family history.

About 200,000 people in the United States are diagnosed with the condition each year.