Aortic Aneurysm

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The goal of treating an aortic aneurysm is to prevent dissection or rupture, the likelihood of which increases with the size of the aneurysm. Once an aneurysm develops along the aorta, it will not disappear or reduce in size on its own. Some small aneurysms will remain stable in size for many years, while others increase in size over time. Most aneurysms grow at rates less than ¼ of an inch per year; however, growth rates can vary substantially between aneurysms.

Treatment depends on size, type, and location of the aneurysm as well as a person's general health. If the diameter of an aneurysm is small (less than 1½ inches) and there are no symptoms, your doctor may suggest a watch-and-wait approach while prescribing medications to control your blood pressure and lipid levels. Although these medications are used to slow the growth of an aneurysm, they are not a cure. Eventually, most aortic aneurysms will need to be repaired to avert rupture or dissection.

This section contains more information on:

  • Criteria for surgical repair
  • Monitoring
  • Medication
  • Open abdominal or open chest surgery
  • Endovascular surgery
  • Treatment of aortic dissections
  • Criteria for surgical repair

    Repair of an aortic aneurysm is recommended when the risk of rupture or dissection outweighs the risk of surgery. Risk of death resulting from surgical repair can be as low as less than 1 percent for an otherwise healthy person, depending on the location of the aneurysm. Research has shown that a 2-inch-wide aneurysm has a 5 percent or 1 in 20 chance of rupturing within one year; a 2 ¾-inch aneurysm has a 20 percent—or 1 in 5—chance of rupture within one year.

    For most people, the repair of an aortic aneurysm should be discussed with their physician if one or more of these criteria are met:

    • Size—aneurysms 1.6 inches in diameter or larger
    • Growth rate—aneurysms increasing in size at more than 1/8 to 1/4 inch per year
    • Symptoms—onset of symptoms
    • Leakage—positive evidence of leakage
    • When an aortic aneurysm meets any of these criteria, surgical repair should be considered. However, individual circumstances can supersede these criteria. For instance, surgery to repair an aneurysm may be considered earlier for people with Marfan syndrome or people who have a bicuspid aortic valve.

      Aortic aneurysms that have ruptured or dissected may be repaired with emergency surgery, but the outcome is not generally as good as when the aneurysm is electively treated before it ruptures. Furthermore, many people with a ruptured aortic aneurysm die before they reach the hospital. Therefore, elective surgical repair to avert an aortic rupture or dissection is highly recommended.

      Monitoring

      If the aneurysm is small—less than 2 inches wide—and there are no symptoms, your doctor may recommend "watching and waiting." Regular checkups, including an abdominal ultrasound/echocardiogram, CT scan, or MRI scan, are recommended once or twice per year. During this time, medications may be prescribed to help control your blood pressure and lipid levels to slow the growth of the aneurysm and reduce your risk for rupture or dissection.

      Medication

      Medications have no direct impact on an aneurysm, except by controlling the conditions that promote aneurysm growth. If the aneurysm is small, medication may be recommended to control lipid levels and blood pressure.

      Lipids are fats circulating in your bloodstream, also known as cholesterols and triglycerides. The ratio of low density lipoprotein cholesterol (LDL) to high density lipoprotein cholesterol (HDL) affects the risk of developing plaque in your arteries. Arterial plaque can promote development of aortic aneurysms and/or dissections. Ideally this ratio should be low—a low LDL coupled with a high HDL. Generic drugs used to control lipid levels and establish favorable LDL to HDL ratios include statins, cholestyramines, colestipol, or gemfibrozil.

      Anti-hypertensives such as beta-adrenergic blockers (beta blockers) may also be used to lower blood pressure to help reduce the growth rate of aortic aneurysms. Beta blockers are a group of more than a dozen different drugs that slow the heart rate, decrease the blood pressure, and reduce the contraction strength of the heart. However, some people may not be able to tolerate the side effects, such as nightmares, impotence, and fatigue.

      Open abdominal or open chest surgery

      The current standard treatment for repairing a thoracic or an abdominal aortic aneurysm is surgically removing the weak section of the aortic wall and replacing it with a tube made of Dacron. The tube, also known as a graft, is spliced in and sewn in place with permanent suture material. Over time, the blood vessel's normal thin inner lining of cells grows over inside of the Dacron tube, making a durable conduit for blood flow. The operation to repair an aneurysm can be surgically complex, depending upon the location of the aneurysm.

      Repairs along the ascending aorta are the most straightforward of thoracic aortic aneurysm repair procedures, with the surgeon using an incision in the front of the chest. During this open-heart procedure, the patient is placed on a cardiopulmonary bypass machine, which circulates oxygenated blood to the body while the surgeon replaces the diseased section of the aorta with a graft. In patients with a bicuspid aortic valve, a congenital defect of the valve between the heart and the aorta, the valve may also be repaired or replaced during the operation. Valve repair or replacement is recommended if the valve is leaking or narrowed, or the patient may elect to have the bicuspid valve replaced to avoid a second heart surgery in the future.

      Aneurysms located along the aortic arch also require open heart surgery with the surgeon accessing the aneurysm from the front of the chest. However, aortic arch repairs involve disconnecting the arteries that supply blood to the brain from the diseased aortic arch and reattaching them to the graft. This procedure interrupts blood flow to the brain. In these operations, the patient is not only placed on cardiopulmonary bypass to take over the functions of the heart and lungs by pumping blood to the body but also undergoes hypothermic cooling.

      Hypothermic cooling lowers the patient's internal body temperature to protect the brain while the arch is replaced. At 18 degrees centigrade (64.4 degrees Fahrenheit), blood flow to the brain can be interrupted for up to 30 minutes with no detectable effects on brain function. Recently, some surgeons have started using a specialized technique known as selective antegrade cerebral perfusion to circulate oxygenated blood into the brain during this procedure, which decreases the overall amount of time blood flow to the brain is interrupted.

      If the aneurysm involves the descending thoracic aorta or the thoracic abdominal aorta, an incision on the left side of the chest will most likely be used. For this procedure, the cardiopulmonary bypass machine may not be necessary.

      Abdominal aortic aneurysm repair does not require cardiopulmonary bypass. The surgeon typically uses an incision either in the abdomen or along the side or flank. Abdominal aortic aneurysm may also be repaired using less invasive endovascular surgery.

      Recovery from open abdominal or chest surgery for aortic aneurysm repair varies depending upon the surgical procedure involved and the patient's overall health. Some people may need only one month and others may need two months of recovery time before returning to their daily routine after aneurysm surgery. Recovery starts in the hospital with the first few days routinely spent in the intensive care unit. Typically, patients spend a total of seven to 10 days in the hospital, depending upon the patient's condition and the operation performed.

      When an aneurysm is repaired electively to avert rupture or dissection, the risk of death depends upon the location of the aneurysm, the overall health of the patient, and the skill of the surgeon. Risks can be as low as less than 1 percent for a repair of the ascending aorta performed by a skilled surgeon in an otherwise healthy individual. The risks increase slightly for repairs involving the aortic arch, are higher for repairs of the descending thoracic aorta, and are still higher for repairs of the abdominal aorta. The highest risks are associated with repairs of thoraco-abdominal aortic aneurysm, which can have up to a 10 percent risk of death. Thoraco-abdominal aneurysm repairs also have a 5 to 10 percent risk of paraplegia. Risks of surgery increase with the patient's age and presence of other health problems.

      Other less severe complications of aneurysm repairs include wound infection, blood clots, bleeding, kidney failure, pneumonia, erectile dysfunction, and leakage around or behind an endovascular graft.

      Endovascular surgery

      Endovascular surgery is a less invasive alternative to open abdominal or heart surgery that uses a catheter equipped with a stent graft to repair the aortic aneurysm. A national study conducted at medical centers throughout the United States indicates that endovascular repair of abdominal aortic aneurysms has fewer complications than open abdominal surgery. The procedure results in less blood loss, less trauma to the aorta, and fewer or even no days in the hospital's intensive care unit.

      However, not everyone is a good candidate for this procedure. The choice between an open abdominal procedure and an endovascular procedure depends on many factors and is best determined by the medical team in consultation with the patient. Stent grafts are generally used in older patients because open abdominal surgery is riskier in this group and because the long-term outcomes of stent grafts are not as well understood.

      In this procedure, a stent graft consisting of a polyester tube inside a metal cylinder is attached to the end of a catheter, a long, thin tube. The catheter is inserted into the bloodstream, usually through an artery in the leg. Watching the progress of the catheter on an X-ray monitor, the surgeon threads the stent graft into the weak part of the aorta where the aneurysm is located.

      Once in place, the stent graft is expanded, reinforcing the weakened section of the aorta to prevent rupture of the aneurysm. The metal frame expands as if it were spring loaded, holding tightly against the wall of the aorta. The blood flows through the stent graft, avoiding the aneurysm. Blood flow to the aneurysm is cut off, typically causing the aneurysm to shrink over time. This technique avoids using a large incision in the abdomen and cutting away the damaged section of the aorta.

      The success rate of stent grafts to treat abdominal aortic aneurysms has risen to 90 percent. Although the endovascular procedure reduces recovery time to less than two weeks as opposed to one to two months with open abdominal repair, it still carries risk. The most common complication of this procedure is an endoleak, when blood leaks from the graft into the body cavity. And because the procedure is relatively new, the long-term results are unknown. Patients who have repair of their aortic aneurysms with stent grafts will need to be evaluated every six months initially to ensure that no complications are developing.

      Treatment of aortic dissections

      Dissections can occur anywhere along the aorta, and treatment largely depends upon the location. Dissections involving the ascending aorta are usually treated with emergency surgery while those involving the descending thoracic aorta are treated with medication.

      Medical treatment usually includes aggressive control of blood pressure and heart rate while the descending thoracic aorta heals. About 1 out of every 10 people dies during medical treatment of a descending thoracic aortic dissection. If surgery is required, the risk of dying is higher –– about 30 percent. Every effort is therefore made to treat these aneurysms with medication.

      The operation for aortic dissection consists of replacing a portion of the aorta with a synthetic material. Surgical repair of a dissection in the descending thoracic aorta is complex with the best results achieved by surgeons who have special expertise in these procedures.

      Last reviewed on 2/10/2009

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