Abdominal Aortic Aneurysm (AAA): Causes, Symptoms, Diagnosis, And Treatment

The aorta is the largest blood vessel in the body. When it exits the heart, it first ascends, then curves over the heart in the shape of a cane, branching into vessels that supply your head, brain, and arms. Descending down to the chest. it supplies the ribcage, and after it passes the diaphragm muscle, it branches out and provides high-oxygen blood to the stomach, liver, spleen, pancreas, intestines, and kidneys. When the aorta reaches the lower abdomen, it splits into two arteries, each for one of your legs.

Aortic diseases can cause dysfunctions of one or more of these body parts, and this is why the aorta is so important.

The abdominal aorta is the segment of the aorta that starts from the diaphragm muscle and continues all the way until it splits into the left and right common iliac artery. The aortic wall is made out of three layers — the inner layer, which is smooth, the elastic middle layer, and the outer layer.

What is an abdominal aortic aneurysm?

Due to atherosclerosis (a disease where plaque is formed in your arteries, narrowing the lumen), the aortic wall eventually loses its elasticity and becomes less flexible. Also, to a lesser extent, injuries, diseases, and infections of the aorta can be potential causes of aneurysms. The blood continues to flow through the aorta under massive amounts of pressure, extending its walls even more, leading to a permanent local expansion of the aortic lumen, called an aneurysm.

If the aorta is equally expanded, it’s defined as a fusiform aneurysm, which are more common in the abdominal aorta. If a ball shaped bulge is created on one side of the aorta, that’s a saccular aneurysm. If all of the layers of the aortic wall are involved in the dilatation, meanwhile, that’s called a true aneurysm, whereas a false aneurysm involves collections of blood forming between the middle and the outer wall layer. 

If the inner wall is damaged, blood can gush through the tear, separating the inner and middle layer of the wall. That’s how a dissecting aneurysm is formed.

How do you get an abdominal aortic aneurysm?

The main cause of AAA is atherosclerosis, which means that the two large groups of risk factors linked to atherosclerosis are also attributed to AAA. Risk factors are classified depending on whether or not you have control over them.

Factors you can’t control include:

• Age, as it mostly affects people between 50 and 90 years old.
• Gender, since men are four times more likely to have AAA.
• Genetic factors, because about one quarter of people with AAA has a first-degree relative with AAA.

Factors you can control include:

• Smoking, because other than it directly damaging blood vessels, it accelerates plaque formation and increases blood pressure.
• High blood pressure, as it weakens and damages the arteries.
• High levels of fat.
• Obesity.

What are the symptoms of abdominal aortic aneurysms?

The biggest problem with diagnostic aneurysms is that patients usually don’t have any symptoms. However, if symptoms are present, then it’s very likely that the aneurysm has already grown massively.

Large aneurysms can compress nearby structures, preventing blood flow to abdominal organs, eventually leading to organ failure. Also, a blood clot in the aorta may form and break off, which can put you at risk of a stroke or heart attack.

The main complication with having AAA larger than five centimeters (two inches) in diameter is that it can eventually burst, which results in internal bleeding. More than half of people with AAA rupture die as a result of this complication.

How are abdominal aortic aneurysms diagnosed?

As most patients don’t show symptoms, AAA is usually diagnosed coincidentally during other examinations of non-related symptoms. Today, imaging methods present the basis in AAA diagnosis. The imaging methods used in AAA diagnosis are:

• Abdominal ultrasound, a quick and cheap method helpful in initial diagnosis and routine check-ups,
• CT scan, which can detect potential changes both in the aorta and in smaller arteries with great precision, as well as if there are any blood clots, or other effects on internal organs or structures. It involves fair amounts of radiation, so your doctor might evaluate the potential risks and benefits before doing this procedure,
• MRI scan is similar to CT, although it’s more expensive. The benefit is that you’ll avoid radiation, but on the other hand the results are currently less precise than CT,
• Aortography, where contrast agent is injected in the aorta via a catheter. It is very useful in checking if the aneurysm has spread to other arteries, especially the ones supplying the kidneys.

How is abdominal aortic aneurysm treated?

The approach to AAA treatment primarily depends on the size of the aneurysm itself, its location, and kidney status.

• If the aneurysm is less than four centimeters in diameter, and symptoms are absent, it is recommended that you have it checked on ultrasound once or twice a year.
• If the aneurysm measures four to six centimeters, your doctor will evaluate if surgery is necessary.
• Aneurysms that measure more than six centimeters in diameter are most likely to be operated. Operative treatment is the only way the dilated aorta can return to normal.

There are only two types of AAA surgery:

• Classic (open) surgery, which includes removing the damaged part of the aorta and substituting it with a synthetic replacement. The recovery period can be as long as six months.
• Endovascular surgery, or EVAR (endovascular aortic repair), a less invasive procedure, in which a synthetic graft is placed on the damaged part of the aorta, strengthening the aortic wall, minimizing the chance of a potential rupture.