Aortic Aneurysm

Types

Aortic aneurysms are classified by shape, location along the aorta and the process that leads to their formation.

The wall of the aorta is made up of three layers: a thin inner layer of smooth cells called the endothelium, a muscular middle layer which has elastic fibers, and a tough outer layer. When the walls of the aneurysm have all three layers, they are called true aneurysms. If the wall of the aneurysm has only the outer layer remaining, it is called a pseudoaneurysm. Pseudoaneurysms may occur as a result of trauma when the inner layers are torn apart.

Saccular Aneurysm

Fusiform Aneurysms

Most fusiform aneurysms are true aneurysms. The weakness is often along an extended section of the aorta and involves the entire circumference of the aorta. The weakened portion appears as a generally symmetrical bulge.

Saccular Aneurysms

Saccular aneurysms appear like a small blister or bleb on the side of the aorta and are asymmetrical. Typically they are pseudoaneurysms caused either by trauma such as a car accident or as the result of a penetrating aortic ulcer.

Degenerative Aneurysms

Degenerative aneurysms are the most common. They occur as the result of breakdown of the connective tissue and muscular layer. The cause could be cigarette smoking, high blood pressure and/or genetic conditions.

Dissecting Aneurysm

Dissecting Aneurysms

Dissecting aneurysms occur when a tear begins within the wall of the aorta causing the three layers to separate similar to what happens to plywood that is left out in the weather. The dissection (separation of the layers) causes the wall of the aorta to weaken, and the aorta enlarges.

Dissections may occur any place along the aorta and treatment depends upon the location. Frequently, dissections involving the ascending aorta are treated with emergency surgery while those involving the descending thoracic aorta are treated with medication.

Although dissections are uncommon, they are the most common of the acute aortic syndromes. They are lethal if not treated. They should be treated only by surgeons who have special expertise.

See more treatment information related to dissecting aortic aneurysms.

Thoracic Aortic Aneurysms>

The aorta is shaped like an old-fashioned walking cane with the short stem of the curved handle coming out of the heart and curling through the aortic arch, which gives off branches to the head and arms. Then the aorta descends through the chest cavity into the abdomen and separates to provide blood to the abdominal organs and both legs. Thoracic aneurysms can occur anywhere along the aorta above the diaphragm, including the ascending aorta, the aortic arch, and the descending thoracic aorta.

Up to 25 percent of aortic aneurysms are thoracic. They can result from various connective tissue disorders (such as Marfan's syndrome), atherosclerosis, previous dissection of the aorta, prolonged high blood pressure (hypertension), and trauma (usually falls or motor vehicle accidents).

See more treatment information related to thoracic aortic aneurysms.

Abdominal Aneurysm

Abdominal Aortic Aneurysms

Abdominal aortic aneurysms are located along the portion of the aorta that passes through the abdomen. Continuing from the thoracic aorta, the abdominal aorta carries blood down through the abdomen until it eventually splits off into two smaller arteries that provide blood to the pelvis and legs.

Abdominal aortic aneurysms are far more common than thoracic aortic aneurysms, comprising up to 75 percent of aortic aneurysms. They can affect anyone, but are most often seen in men ages 40 to 70. Most abdominal aortic aneurysms are caused by atherosclerosis.

See more treatment information related to abdominal aortic aneurysms.