A technique that patches a bulging artery without open surgery is not as effective as open surgery in the long term, the Associated Press (AP) reported June 9 based on a Dutch study published in the New England Journal of Medicine. Endovascular repair uses a thin tube to carry a patch through the abdominal aortic artery to the site of the bulge, or aneurysm. In open surgery, the abdomen is cut open to make the repair. In the first month, the non-surgical approach reduced death rates by three-quarters, the Dutch researchers reported earlier. But in the new study they said that after two years the death rate for the sickest patients was higher with this procedure than with open surgery.
By Howard LeWine, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
The normal size of the aorta (the large artery that exits the heart, travels through the chest and down into the abdomen) is about 1 inch (2.5 centimeters) in diameter or a little smaller. As we age, the artery tends to expand a little. An abdominal aortic aneurysm is a dilatation of that portion of the aorta that resides within the belly. If the diameter increases above 3 centimeters, the person is said to have an abdominal aortic aneurysm (AAA).
Relatively small abdominal aortic aneurysms of 3 to 4 cm are quite common. Men have a much higher risk of aneurysm than women. White males of European ancestry are most susceptible; they have three times the risk of African-American men.
Other than male sex, the other risk factors are older age, smoking, high blood pressure, known atherosclerosis (such as coronary artery disease) and positive family history of AAA.
Older males who have smoked are at a high enough risk that screening is recommended. Current and former male smokers, ages 65 to 75, should be screened a single time with ultrasound to see if they have AAA.
Screening is important because most aneurysms continue to enlarge without any symptoms until they leak or rupture. Ultrasound is an easy and safe way to keep track of the size. This is important because the size of an aneurysm correlates closely to risk of rupture. An aneurysm of less than 4 cm has a low risk of rupture. Aneurysms over 5.5 cm in diameter have a high enough rupture risk to warrant repair.
What Changes Can I Make Now?
Doctors want to find aneurysms and track changes in size before they rupture. Compared to a planned scheduled repair, emergency repair of AAA once it has ruptured carries a much higher mortality.
Aneurysms seen on ultrasound that are less than 4 cm require repeat ultrasounds yearly. People with AAAs between 4 and 5 cm should have an ultrasound every six months, and those with diameters over 5 but less than 5.5, every three months.
Vascular surgeons have two options to repair abdominal aortic aneurysms. The traditional method is abdominal surgery that involves temporary clamping of the aorta and repair of the vessel with an external graft.
The newer method is called endovascular surgery. Small cuts are made in the groin over a branch of the artery that goes to the leg. A special device allows a tube called a stent to be threaded into the proper position and deployed at the site of the aneurysm. The stent protects the native wall of the abdominal aorta from the pressure inside the artery, and ideally halts any expansion and weakening of the artery wall.
Earlier studies comparing the two methods of repair have shown short-term outcomes (the first couple of months) to be better with the endovascular repair. In the June 9 issue of the New England Journal of Medicine, the comparison of the two techniques was extended to what happens after two years. It looks like the two procedures are relatively equal.
Because of the expense of the medical devices needed for endovascular repair, the cost of the newer procedure is higher than the older surgery. But for certain patients, endovascular repair will have overall less expense because hospital stays and recovery tend to be shorter.
What Can I Expect Looking to the Future?
Vascular surgeons will continue to use both techniques for repair of abdominal aortic aneurysms. In general, the choice of which to use will depend on the age of the patient, what other medical problems he or she has, and most important, the location and appearance of the AAA as seen on CT scan, MRI or angiogram.
Older and frailer patients who are more likely to have complications from an abdominal incision and prolonged anesthesia are candidates for endovascular repair, assuming that technically it is the best option. Younger and generally healthier patients are probably better served with more formal abdominal surgery, although as the endovascular devices and techniques improve, this may change.
