Endovascular Grafts
Endovascular Grafts |
|
When most people hear "aneurysm," they think of dangerous bleeding in the brain. But this abnormal, egg-shaped widening of a blood vessel can occur anywhere. Many of us walk around for years with small, slowly growing aneurysms with no symptoms. As an aneurysm enlarges, though, it can rupture and lead to death. The most common site for an aneurysm is in the body's largest artery, the aorta, just below the kidneys, where it forks into arteries that supply each leg. Doctors detect these aneurysms in x-rays taken for other purposes or by feeling a pulsing in the abdomen during routine exams. For small aneurysms, the treatment is to "watch and wait." But at 5 centimeters, the risk of rupture exceeds the risk of surgical repair. Although highly successful, traditional repair involves major abdominal surgery and a month of recuperation. Recently doctors reported on a less invasive method for repairing abdominal aneurysms. Through a small slit in the groin,we insert a catheter carrying a collapsed metal frame covered with fabric. The procedure is known as "endoluminal stent-graft." Guided by sophisticated angiographic imaging, we are able to snake the catheter through the femoral artery to the aneurysm. A balloon within the catheter is then inflated, pushing open the stent, which attaches with tiny hooks to healthy arterial wall above and below the aneurysm. This creates a channel for blood flow that bypasses the aneurysm. Most patients receive Y-shaped device designed for the fork in the aorta; patients with aneurysms higher in the aorta received straight tubes.
In the US, vascular surgeons and radiologists at some 30 medical centers have been using endoluminal stent-grafts in clinical trials required before the FDA approved the devices for widespread use (see FDA Approves Endovascular Grafts). In October, 1999 the FDA approved the device for general use. One of the leading centers in the USA was UCLA, where the first Endoluminal Stent Graft was deployed. Dr. Kafie received his endovascular training at UCLA. Dr. Yonehiro received his training at Stanford Medical center.
In the abdomen, where 95 percent of aneurysms occur, the aorta is about three fourths of an inch in diameter and is somewhat like an elastic hose. With age and some genetic influence, a soft spot or bubble can develop. As the aneurysm enlarges under pressure from blood flow, the wall becomes thinner, like a balloon, and eventually bursts. Nearly all ruptured aneurysms are fatal, except in the few patients who survive to reach a hospital. Traditional repairs involves sewing in a dacron tube to replace the diseased aorta. In recent years, the risk of this operation has dropped to a 1 to 2 percent mortality rate in top hospitals, with stays of five or six days, even in high-risk elderly patients. This is the standard against which any new treatment must be judged. Endoluminal repair of aneurysms has evolved over the past 20 years.
In the European study, as well as in a report from Australia on a slightly different device, the biggest problem is in obtaining a tight and durable seal without migration or kinking, which is especially difficult because of the arterial wall's unpredictable size, shape, and surface. All this must be done by a device that can fit in a delivery system just slightly wider than a drinking straw. It is testimony to the creativity of engineers and doctors that endoluminal aortic aneurysm repair is now sufficiently safe to warrant prospective clinical trials to compare it with standard aortic surgery.
There is little doubt that creative solutions will come and endoluminal technology will play an increasing role in treating vascular disease.
| Traditional surgery for abdominal aortic aneurysm (AAA) repair requires a large incision from just below your breastbone to the top of your pubic bone (Figure 1). Your surgeon opens the aneurysm and sews a vascular graft in place. The endovascular procedure requires two small incisions in the groin (Figure 2). Using an x-ray imaging device, a delivery catheter (tube) containing a vascular graft is guided up through a blood vessel in your leg into your aorta and the graft is placed inside your aneurysm. The graft contains metal which can be seen with x-ray equipment. |  |
 |
There are several types of endovascular grafts that are available under investigational use only. Currently, there are only two grafts that are approved by the Food and Drug Administration (FDA) for general use. In order for your physician to deploy these grafts, it is advisable that he/she undergo adequate training in endovascular techniques as well as "hands-on" training at one of the few referral centers across the nation. After appropriate certification in vascular and endovascular techniques, he/she must undergo certification for deployment of these endovascular grafts. It is important that you discuss with your physician his/her experience.
Our surgeons have the most extensive experience in the area and have collectively placed the most endoluminal devices in region.
