An aortic aneurysm is a weak area in the aorta, the main blood vessel that carries blood from the heart to the rest of the body. As blood flows through the aorta, the weak area bulges like a balloon and can burst if the balloon gets too big.
In the past 30 years, the occurrence of Abdominal Aortic Aneurysms (AAA) has increased threefold. AAA is caused by a weakened area in the main vessel that supplies blood from the heart to the rest of the body. When blood flows through the aorta, the pressure of the blood beats against the weakened wall, which then bulges like a balloon. If the balloon grows large enough, there is a danger that it will burst. Most commonly, aortic aneurysms occur in the portion of the vessel below the renal artery origins. The aneurysm may extend into the vessels supplying the hips and pelvis.
Once an aneurysm reaches 5 cm in diameter, it is usually considered necessary to treat to prevent rupture. Below 5cm, the risk of the aneurysm rupturing is lower than the risk of conventional surgery in patients with normal surgical risks. The goal of therapy for aneurysms is to prevent them from rupturing. Once an abdominal aortic aneurysm has ruptured, the chances of survival are low, with 80 to 90 percent of all ruptured aneurysms resulting in death. These deaths can be avoided if an aneurysm is detected and treated before it ruptures.
Currently, there are three treatment options for AAA:
Watchful waiting - Small AAA's (less than 5 centimeters or about 2 inches), which are not rapidly growing or causing symptoms, have a low incidence of rupture and often require no treatment other than "watchful waiting" under the guidance of a endovascular specialist. This typically includes follow-up ultrasound exams at regular intervals to determine if the aneurysm has grown.
Surgical Repair - The most common treatment for a large, unruptured aneurysm is open surgical repair by a vascular surgeon. This procedure involves an incision from just below the breastbone to the top of the pubic bone. The surgeon then clamps off the aorta, cuts open the aneurysm and sews in a graft to act as a bridge for the blood flow. The blood flow then goes through the plastic graft and no longer allows the direct pulsation pressure of the blood to further expand the weak aorta wall.
Interventional Repair - This minimally invasive technique is performed by an interventional radiologist using imaging to guide the catheter and graft inside the patient's artery, rather than making a large incision. For the procedure, an incision is made in the skin at the groin through which a catheter is passed into the femoral artery and directed to the aortic aneurysm. Through the catheter, the surgeon passes a stent graft that is compressed into a small diameter within the catheter. The stent graft is advanced to the aneurysm, and then opened, creating new walls in the blood vessel through which blood flows.
This is a less invasive method of placing a graft within the aneurysm to redirect blood flow and stop direct pressure from being exerted on the weak aortic wall. This relatively new method eliminates the need for a large abdominal incision. It also eliminates the need to clamp the aorta during the procedure. Clamping the aorta creates significant stress on the heart, and people with severe heart disease may not be able to tolerate this major surgery. Stent grafts are most commonly considered for patients at increased surgical risk due to age or other medical conditions.
The stent graft procedure is not for everyone, though. It is still a new technology and we don't yet have data to show that this will be a durable repair for long years. Thus, people with a life expectancy of 20 or more years may be counseled against this therapy. It is also a technology that is limited by size. The stent grafts are made in certain sizes, and the patient's anatomy must fit the graft, since grafts are not custom-built for each patient's anatomy.
