The aorta is the large artery that exits in the heart and delivers blood to the body. It begins at the aortic valve that separates the left ventricle of the heart from the aorta and prevents blood from leaking back into the left ventricle after a contraction, which is actually when the heart pumps blood. The various sections of the aorta are named based upon “arch-like” initial design and the location of the aorta in the body. Thus, the beginning of the aorta is referred to as the ascending aorta (basically meaning the blood going against resistance due to the vessel being a hill for the blood to go up), followed by the arch of the aorta, then the descending aorta (which is the blood going downward via gravity with the help of the heart pumping the blood of course). The portion of the aorta that is located in the chest (called thorax) is referred to as the thoracic aorta, while the abdominal aorta (the part of the aorta below the thorax region) is located in the abdomen. The abdominal aorta extends from the diaphragm (at the bottom of the lungs like a floor to divide the lungs from the organs in the abdomen) to the mid-abdomen where it splits into the iliac arteries and when it reaches the legs the femoral arteries now start which supplies to the legs oxygenated blood. This is why commonly a cardiac catheterization to visualize the aorta and sometimes the left side of the heart is done starting in the femoral artery since in time it diverts into starting the abdominal aorta.

An aneurysm is an area of a localized widening (dilation) of a blood vessel. The word “aneurysm” is borrowed from the Greek “aneurysma” meaning “a widening”.

An aortic aneurysm involves the aorta, the major artery that leaves the heart to supply blood to the body. An aortic aneurysm is a dilation or bulging of the aorta..

Most aortic aneurysms are fusiform. They are shaped like a spindle (“fusus” means spindle in Latin) with widening all around the circumference of the aorta. (Saccular aneurysms just involve a portion of the aortic wall with a localized out pocketing).

What is inside an aortic aneurysm?

The inside walls of aneurysms are often lined with a blood clot that forms because there is stagnant blood. The wall of an aneurysm is layered, like a piece of plywood.

Who is most likely to have an abdominal aortic aneurysm?

Abdominal aortic aneurysms tend to occur in white males over the age of 60. In the United States, these aneurysms occur in up to 3.0% of the population. Aneurysms start to form at about age 50 and peak at age 80. Women are less likely to have aneurysms than men and African Americans are less likely to have aneurysms than Caucasians.

There is a genetic component that predisposes one to developing an aneurysm; the prevalence in someone who has a first-degree relative with the condition can be as high as 25%.

Collagen vascular diseases that can weaken the tissues of the aortic walls are also associated with aortic aneurysms. These diseases include Marfan syndrome and Ehlers-Danlos syndrome

Aortic aneurysms can develop anywhere along the length of the aorta but the majority are located in the abdominal aorta. Most of these abdominal aneurysms are located below the level of the renal arteries, the vessels that provide blood to the kidneys. Abdominal aortic aneurysms can extend into the iliac arteries.

What shape are most aortic aneurysms?

Most aortic aneurysms are fusiform. They are shaped like a spindle (“fusus” means spindle in Latin) with widening all around the circumference of the aorta. (Saccular aneurysms just involve a portion of the aortic wall with a localized out pocketing).

Stayed tune for Part II on Aortic Aneurysms tomorrow!