What is an infrarenal aortic aneurysm?

The largest artery in the human body is the aorta. It starts in the heart and moves oxygenated blood through the body. An aneurysm is a balloon-shaped bulge in an artery caused by a weakness in the vessel. Aneurysms of the aorta that occur below the kidney are called infrarenal aortic aneurysms. It is the most common type of abdominal aortic aneurysms (AAA).

The causes of an infrarenal aortic aneurysm are not completely clear, but there are theories that suggest that genetics and certain behaviors contribute to its formation. Genetics seem to be an important factor in men. Cigarette smoking is also considered a contributing factor, and is seen in a high percentage of patients. Other causes can be atherosclerosis, hardening of the arteries, as well as infection and trauma.

Statistics show that more than 90% of AAAs are infrarenal aortic aneurysms. AAAs can also occur at or above the kidneys; if they are above the diaphragm, they are no longer considered abdominal aortic aneurysms, but instead are called thoracic aortic aneurysms. Infrarenal aortic aneurysms often extend into the leg and lower abdomen, and into the iliac arteries.

The greatest danger of having an infrarenal aortic aneurysm, or any aneurysm, is that it ruptures. Most aneurysms develop gradually over time and can be symptomless, which is why they are so dangerous. A dissecting aneurysm is the most dangerous and occurs when a layer of the blood vessel tears or tears, and is then followed by severe pain. Many times the pain will subside, partially or completely, but the blood vessel wall is still weakened, increasing the chance of rupture. This is often mistaken for a cramp or other temporary pain.

Since most infrarenal aortic aneurysms have no symptoms, they are difficult to diagnose until they burst or rupture. They are often found when doing a physical exam, ultrasound, or CT scan for another problem. If the aneurysm is closer to the skin, it may be visible, but most aneurysms occur deeper in the body. Computed tomography is the most reliable test, with 100% sensitivity to aneurysms. Men between the ages of 65 and 75 are at greatest risk, and it is recommended that they be screened at least once if they are smokers.

An infrarenal aortic aneurysm is treated like other aneurysms, most often with blood-thinning medications or surgery. Quitting smoking is recommended as a preventative measure for those with small aneurysms. If an aneurysm bursts, surgery is done, but it is often unsuccessful because many patients have already lost too much blood by the time they arrive at the hospital. Once an aneurysm bursts, blood loss only takes a few minutes to death.

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