Aneurysm of the aorta. Ken U. Ekechukwu, MD, MPH, FACP.

What is aorta?
The aorta is the large artery that carries blood from the heart and distributes it to the rest of the body. The portion of the artery in the chest is called the thoracic aorta, while the portion in the abdomen or belly is the abdominal aorta. In the chest and abdomen the aorta lies behind other viscera, next to the vertebral column. It is the largest artery in the body, measuring about 3 cm in the chest and 2.5 cm in the abdomen, but these measurements vary with sex and age, being larger in men and the elderly.

What is aneurysm?
All arteries in the body have three layers: the innermost layer (tunica intima) is in contact with blood and elastic; the middle layer (tunica media) is mainly composed of smooth muscle and supporting tissue; and the outermost layer (tunica externa or adventitia) is composed of fibrous tissue. These layers, together, keep blood inside an artery and propel it forward.  Weakness in the wall of an artery causes abnormal widening of the artery, an aneurysm (Gr. aneurysma, a widening). Any artery in the body can develop an aneurysm (brain, heart, lung, aorta, liver, kidney, spleen, etc.), but this discussion is about aneurysms of the aorta. A true aneurysm occurs when weakness of all three layers of an artery enlarges the artery by 50% or more of its normal diameter. When such weakness affects fewer than all three layers, the resulting local bulge is called a pseudoaneurysm (pseudo means false). This writing is on true aneurysms not caused by infection.

Why do aneurysms occur?
There are many reasons why true aneurysms occur: some genetic abnormalities that run in families, infections of an artery (bacterial, viral, fungal), autoimmune diseases that cause systemic inflammations that involve the arteries, hypertension, smoking, hypercholesterolemia, diabetes mellitus, and trauma, to name a few.

Why should I be concerned about aortic aneurysms?
The primary concern in all aneurysms is the risk of sudden rupture, which can be catastrophic. The risk of death is high and morbidity is gruesome. The situation is even grimmer when you recognize that most aneurysms grow quietly until they rupture, explaining why most aneurysms of the aorta come to attention serendipitously during investigation for other problems. But now, you can be screened for the disease if you are of the right age and your risk profile fits. Please speak to your health care provider. The risk of rupture rises as an aneurysm grows, taking a steep climb when an aneurysm of the ascending aorta attains 6 cm in diameter or an aneurysm of the descending thoracic aorta or the abdominal aorta is 5 cm in diameter. This explains why current standard-of-care recommends treating these aneurysms when they attain these measurements.

How do I know that I have an aortic aneurysm?
There is a good chance that you may not know that you have an aortic aneurysm. If, however, you have risks for the disease it is good to speak to your healthcare provider. Such risks include a family history of aneurysms, smoking, hypertension, hypercholesterolemia, and diabetes mellitus.

Is there treatment for aortic aneurysms?
First, not all aneurysms need immediate attention. Chest and abdominal aortic aneurysms need to grow to the right size to demand fixing. So, if your aneurysm is still ‘a baby aneurysm’ and not the result of an infection, your health care provider may elect to watch it and control your blood pressure and other health problems with medications.  More important is taking steps on your own to prevent the development of an aneurysm including avoiding the use of tobacco. Aneurysms that have grown to treatable sizes may be addressed surgically or endovascularly.

Endovascular repair of an abdominal or thoracic aneurysm is a minimally invasive therapy performed by interventional radiologists and other vascular specialists. It requires the insertion of a special kind of stent called a stent-graft across the dilated part of the aorta to reinforce the wall and separate (actually, protect) it from the forces of blood pulsation. It is reasonably safe and effective in capable hands and requires a short hospital stay, barring unexpected outcomes. Most patients who receive endovascular repair of an aortic aneurysm return to normal activities within 2 weeks. The treatment is not offered to every patient with aortic aneurysm, because certain structural characteristics of the aneurysm may forbid endovascular repair.