What is dissecting aortic aneurysm?

The aorta is composed of three layers and aortic dissections occur when the layers separate the way plywood will separate if left out in the weather.

When this occurs, patients typically experience severe pain in the chest or back. This most frequently sends patients to the emergency room where the diagnosis may be made.

Dissections may involve the ascending aorta, the descending thoracic and abdominal aorta, or the entire aorta. The risk of death depends on the extent of the dissection or rupture.

The risk is highest for those aneurysms involving the ascending aorta. For this reason, most of these aneurysms are treated surgically as an emergency.

Dissections of the descending thoracic aorta can often be treated with blood pressure control.

The medical treatment of aortic dissection includes aggressive control of blood pressure and heart rate while the aorta heals.

The risk of death with medical treatment of descending thoracic aortic dissection is about 10 percent. If surgery is required, the risk is higher – about 30 percent. Every effort is therefore made to treat these patients with medication.

Once the acute dissection has healed, adequate control of blood pressure may eliminate the need for surgery. Lifelong monitoring of the aorta’s diameter is required, because a previously dissected descending thoracic aorta may enlarge and rupture.

The risk of surgery for an ascending aortic dissection is also significant. The risk of death ranges from 10 to 20 percent. The risk is less for people who come to the operating room in good condition, and greatest for those who are in shock when they are brought to the operating room.

In the operation, the surgeon removes the dissected ascending aorta and replaces it with a polyester graft. Sometimes part of the aortic arch or the aortic valve is replaced. In this situation, long-term blood pressure control and monitoring of the remaining aorta’s diameter are critically important.

— From the Mayo Clinic website www.mayoclinic.org