Abdominal Aortic Aneurysm (AAA)
Endovascular Repair of Abdominal Aortic Aneurysms
What is an Abdominal Aortic Aneurysm (AAA)?
An aortic aneurysm is a balloon-like bulge in the wall of the thoracic or abdominal aorta, the large blood vessel that runs down the middle of the body. Due to the constant tension on the wall from the pressure of blood flow, this sac progressively enlarges until it ruptures. Abdominal aortic aneurysms occur in 5 to 8 percent of people older than 60 years of age. Approximately 15,000 people die each year of from a ruptured abdominal aneurysm, making it the 13th leading cause of death in the United States. Mortality once and aneurysm has ruptured is estimated to be from 74 to 90 percent, making elective repair the treatment of choice for patients with aneurysms 5 to 5.5 cm in diameter or larger. Most aneurysms are diagnosed incidentally and are small in size. Those at increased risk of abdominal aortic aneurysm have a history of cigarette smoking, have a first-degree relative with an aortic aneurysm or peripheral vascular disease, carotid artery disease or hypertension.
When should an abdominal aortic aneurysm be repaired?
The current morbidity and mortality rates for the elective surgical repair of asymptomatic abdominal aneurysms in average patients are between 3 and 5 percent, but the complication and death rated for patients with multiple additional or severe medical conditions is higher. The current SVS-ISCS guidelines recommend repair of abdominal aneurysms 5 cm or greater in diameter, but a recent study suggests that most aneurysms do not need to be repaired surgically until they are 5.5 cm in size in men.
However, these are not rigid values. Smaller aneurysms are repaired when they cause symptoms, if they are rapidly expanding, or when they occur in women (the baseline size of the aorta in women is smaller), since aneurysms are at higher risk of rupture under these circumstances. The average rate of expansion for abdominal aneurysms is between 0.3 and 0.5 cm per year. Most known aneurysms are followed with semi-annual ultrasound examinations.
What is the surgical treatment for AAA?
The traditional treatment of aortic aneurysms has been open surgery. The first successful replacement of an abdominal aortic aneurysm was in 1951. Over the years, the surgical techniques have been refined. The current operation is technically called “exclusion endoaneurysmorrhaphy”. The surgeon opens the abdomen with a scalpel and lifts the intestines off the aorta. The blood flow in the aorta is temporarily halted by applying clamps and then the aneurysm is opened. A branched fabric tube shaped like a small pair of pants is sewn into the normal segments of vessel above and below the aneurysm.
What is Endovascular Aneurysm Repair?
Although the morbidity and mortality rates from surgical AAA repair are relatively low, they are not insignificant, so doctors began to think of less invasive ways to repair the aorta. The first endovascular aortic grafts were developed in the 1980’s, and the first endovascular device was implanted at UCLA in 1993. Even though the early devices are now considered “first generation”, the clinical trials using these implants resulted in less blood loss, shorter hospital stays and fewer respiratory and cardiac complications.
Endovascular aneurysm repair involves the introduction of a vascular prosthesis through either the femoral or iliac artery and into the aneurysm, where it provides a channel for blood flow to the lower extremities while excluding the aneurysm sac from the circulation. This procedure involves only a small incision in each groin. The diagram shows the arteries that are involved in the placement of the Excluder™ prosthesis. The enlarged area shows the final position of the assembled device.
How do I know if I have an aneurysm?
Your doctor can sometimes find an aneurysm during a physical examination, but most often the diagnosis has to be confirmed with imaging. A CT scan is an accurate way to evaluate an aneurysm, but most often an ultrasound examination is adequate to make the make the diagnosis and measure the aneurysm diameter. Because of the danger of an undiagnosed aortic aneurysm, Medicare decided that beginning in January 2007 it would pay for screening ultrasound tests to detect AAA in those at risk. Medicare will pay for a one-time screening ultrasound if an extension of a general preventative examination by your treating physician you have at least one of the following risk factors:
• A family history of abdominal aortic aneurysm
• You are a male aged 65 to 75 and have smoked at least 100 cigarettes in your lifetime.
• You are in a specific beneficiary category determined by CMS (ask your provider).
How can I find out more?
If you have been diagnosed with a AAA and want to know more about endovascular treatment options, call the Utah Vascular Clinic at 281-0027 and ask for a consultation with one of our doctors.