Aorta is the largest artery of the body. Its average normal diameter in the chest (thoracic aorta) is up to 28mm, and around 20mm in the abdomen (abdominal aorta). The normal diameter of the abdominal aorta ranges between 14 – 30 mm.
When a weak area of the abdominal aorta bulges or expands to reach over 1.5 times its average normal diameter, it is called an aortic aneurysm. The pressure of the blood with every heart beat can cause a weakened area of the aorta to gradually bulge (much like a balloon).
The term aortic aneurysm is used as almost equivalent to the term aortoiliac aneurysm, because of the fact that the iliac arteries are quite commonly also aneurysmal in the presence of an abdominal aortic aneurysm and their treatment is typically common. Isolated iliac artery aneurysms are rare. A common iliac artery is considered normal if its diameter is less than 17mm (males) or 15mm (females), ectatic if between 17-25mm, and aneurysmal if above 25mm.
The aneurysms of the aorta are classified as:
If the aneurysm is not treated, the aortic wall continues to weaken and the aneurysm to enlarge. Eventually, the aneurysm becomes large enough and its wall too weak and bursts (ruptures). A ruptured aneurysm can cause very severe internal bleeding leading to shock and death in most cases.
Most people with an aneurysm do not have symptoms, and it is usually diagnosed by investigations done for irrelevant reasons.
If you have symptoms, these may be:
If the aneurysm ruptures, you may feel intense weakness, dizziness or pain and lose consciousness. This is a life threatening situation and you should immediately seek medical care.
Aortic aneurysms are commoner in men. You are at increased risk of developing an aortic aneurysms if you are:
Although hypertension, or high blood pressure, (especially if not well controlled) would intuitively seem to enhance the development and expansion of AAA, it has not been documented to be a factor in population-based studies.
The simplest way to diagnose an arotic aneurysm is by ultrasound scanning of the abdomen. If your physician suspects you might have an aneurysm, he/she may organize one of the following imaging investigations: duplex ultrasonography of the abdominal aorta & the iliac arteries, computed tomography (CT) or magnetic resonance imaging (MRI) of the abdomen.
Not all abdominal aortic aneurysms require repair. The risk for rupture – and consequently the indication for repair – increases together with the size of the AAA.
Whether you need operative repair for your AAA or not shall be decided by your vascular surgeon who is the only physician capable of performing all types of AAA repair.
If your AAA is small (30-50mm), your vascular surgeon will generally recommend watchful waiting with follow-up ultrasound scans (usually every 6-12 months). Abdominal aortic aneurysms in general grow slowly. However, the larger they are, the faster they grow.
As an exception, repair for a small aneurysm may be recommended, (i) if its morphologic features are thought to pose an increased risk for rupture, such as false aneurysms (versus true atherosclerotic aneurysms) or saccular (versus fusiform aneurysms) or (ii) if the aneurysm is inflammatory and causes symptoms or hydronephrosis.
If the AAA is large enough (over 50-55mm), it is generally safer for you to have it repaired. Because the operation carries certain risks, the exact size for which the operation will be elected depends upon any other medical conditions you may have. For example, heart, lung or kidney problems increase the surgical risk. After successful open surgical repair the risk for rupture is zero. Ideally, repair will be recommended when the rupture risk is higher than the surgical risk. Your vascular surgeon will discuss with you in detail the possible risks and complications of the operation.
With regard to isolated common iliac aneurysms, repair is recommended if the aneurysm exceeds 30 to 35 mm in diameter to prevent the risk of rupture. Simultaneous aortic replacement should also be a serious consideration.
If rupture of an abdominal aortic aneurysm occurs, the chance of survival is less than 20%.
The approach may be one of the following:
Most people with an AAA will eventually need repair of their aneurysm with a graft.
For open repair, through an incision in your abdomen, the weakened part of your aorta is replaced with a graft, or a plastic tube, which allows your blood to flow through it.
The graft is made of very strong durable plastic material either Dacron (polyester) or polytetrafluorethylene (PTFE) in the size of normal aorta. The graft lasts for a lifetime and is very unlikely to require replacement. The operation is successful in 90-98% of cases.
Following the operation you will stay in the hopital for 5-8 days. It will take you 2-3 months for a complete recovery, but this period depends on your biological age.
Instead of the open repair, your vascular surgeon may consider this newer procedure, the endovascular repair. Endovascular or endoluminal means that the procedure is done through the wall of your arteries inside their lumen using very fine and long tubes, called catheters. This type of operation is less invasive and may be performed under regional anasthesia.
Initially, a small incision is made in each groin area. During the procedure, the vascular team will use x-ray pictures viewed on a screen to guide a tube (made of plastic and metal material), called stented graft or endograft, to the site of the aneurysm. Like the graft in open repair the endograft reinforces the aorta.
Your recovery time after EVAR is shorter than with the open repair and hospital stay may be reduced to 2-3 days. However, this procedure requires follow-up for a long time (probably for your lifetime) with imaging inestigations, currently CT scans, to confirm that it continues to function properly.
Your aneurysm may not be suitable for this procedure, because of its shape, its extent, its relation to the renal arteries etc. While endovascular repair may be a good option for some patients, in other cases open repair may be the best way to cure the problem.
Your vascular surgeon is the only physician qualified to offer all types of treatment for an AAA, and will help you decide the best method of repair in your particular situation.
It is prudent to improve your general health state even if you don’t need an operation at present: