An aortic aneurysm is the dilation, bulging or ballooning out of part of the wall of the aorta, the artery through which blood flows out of the heart to the body. Aneurysms may occur along the length of the aorta as it runs from the heart, through the chest and down through the abdomen. Aneurysms that occur in the abdomen are known as abdominal aortic aneurysms, and aneurysms that occur in the chest are known as thoracic aortic aneurysms. Both are considered very dangerous conditions and require careful monitoring and sometimes medication or surgical therapy.

The causes and treatments of aortic aneurysms are related to the kind of aneurysm. The greatest risk factor for either kind of aneurysm is age. Studies have estimated that up to 9 percent of people over age 60 have an abdominal aortic aneurysm. Beyond age, the presence of aortic aneurysms may be associated with a number of factors. For example, there is evidence that thoracic aortic aneurysms are closely connected to such diseases as high blood pressure, atherosclerosis (“hardening of the arteries”), Marfan syndrome, and chronic infections such as syphilis or tuberculosis.

Possible factors associated with abdominal aortic aneurysms include atherosclerosis, genetic abnormalities and possibly a malfunction of certain tissues caused by inflammation. The dangers of both types of aneurysm are also greatly aggravated by smoking. Quitting smoking is a very important part of therapy for an aortic aneurysm.

The majority of aortic aneurysms cause no symptoms. While still small, these aortic aneurysms may be managed by controlling high blood pressure, especially with medications called beta blockers. However, larger aortic aneurysms may require surgery to prevent the aortic aneurysm from rupturing (a potentially fatal event). According to the American Heart Association, about 15,000 people die every year from ruptured aortic aneurysm.

In addition to the aorta, any other large blood vessel in the body may develop aneurysms. These blood vessels include those that provide blood to the lower extremities, heart muscle or brain (a cerebral aneurysm).

An aortic aneurysm is the dilation, bulging or ballooning out of part of the wall of the aorta. Typically, the widening of such an area is considered to be an aneurysm when it is more than 1.5 times its normal size. The pressure of blood flow within the aorta, particularly if the walls have been weakened and damaged by plaque buildup, may eventually lead to the aneurysm expanding and rupturing. Ruptures are very painful events that causes massive internal bleeding. The patient usually must be treated within minutes to hours in order to have a chance of survival. The survival rate of those with ruptured aortic aneurysms is less than 50 percent.

Aortic aneurysms may be classified a number of ways. They are often grouped by where they occur along the length of the aorta, or by the form of the aneurysm itself. Forms of aneurysm include:

Aneurysms are also commonly grouped by where they occur along the length of the aorta. If they occur in the ascending aorta, aortic arch or the portion of the aorta that travels through the upper chest (descending thoracic aorta), they are known as thoracic aortic aneurysms. These account for about 25 percent of aortic aneurysms. If they occur in the portion of the aorta that runs through the abdomen, down toward the branch of the iliac arteries, they are known as abdominal aortic aneurysms. They account for about 75 percent of aortic aneurysms.

The underlying causes of aortic aneurysms are somewhat related to their location. Thoracic aortic aneurysms are connected to atherosclerosis (“hardening of the arteries”), inherited disorders such as Marfan syndrome or Ehlers-Danlos syndrome or high blood pressure. Because of their proximity to the heart, thoracic aortic aneurysms may cause heart attack by pressing on the coronary arteries or heart failure by causing the aortic valve to function abnormally. Most patients with thoracic aortic aneurysms also have other forms of heart disease, and as many as 25 percent also have abdominal aortic aneurysms.

Abdominal aortic aneurysms are about three times as common as thoracic aortic aneurysms. They usually occur in patients over the age of 50, and they become more common as people age. They are also much more common (about four to five times) in men as women. The causes of abdominal aortic aneurysms are not completely understood, but they are more common in patients with atherosclerosis and high blood pressure, and inflammation as measured by C-reactive protein, seems to play a role in the process. They also appear to run in families. More than one quarter of patients diagnosed with such an aneurysm have a close relative with the same condition.

Aneurysms in the arteries of the heart can also develop from cocaine use. Researchers feel that a person’s risk increases with the amount of cocaine used, and that this risk is irreversible. Both kinds of aneurysms are also affected by smoking. Cigarette smoking has been shown to cause aneurysms to grow larger and more rapidly, thus increasing their risk of rupture. Quitting smoking is a major element of non-surgical therapy for aneurysm.

Aortic aneurysms often produce no symptoms, but in younger adults, abdominal aortic aneurysms may cause abdominal or lower back pain. Also, the area around the abdominal aortic aneurysm may be sensitive to the touch, or there may be a pulsing mass in the abdomen. Aortic aneurysms are easier to detect in thin people.

If a thoracic aortic aneurysm causes any symptoms, they may include:

However, the most obvious symptoms associated with aneurysms occur after a rupture. In this case, the aneurysm bursts, resulting in massive internal bleeding, often accompanied by sudden and extreme abdominal or back pain. There may also be a pulsing mass in the abdomen. Blood pressure will drop drastically, leading to symptoms of hypotension (e.g., dizziness, weakness, blurred vision or nausea). Rupture is an exceptionally dangerous event, and more than half of patients will die before they reach an emergency room.

The risk of rupture is related to three elements:

• The size of the aneurysm. Studies have shown a relatively low risk of rupture for abdominal aortic aneurysms less than 4 centimeters (about 1.5 inches), and between 4 to 7 centimeters for thoracic aortic aneurysms, depending on where they are located.
  
  
• The growth rate of the aneurysms. Some aneurysms remain relatively stable for a long period, then begin to grow rapidly. Others grow at a fairly consistent pace of half a centimeter annually. Aneurysms that grow more rapidly are more dangerous than slow-growing ones.
  
  
• The presence of symptoms. Studies have shown that aneurysms that cause pain or other symptoms are more likely to rupture than asymptomatic (without symptoms) aneurysms.

Aortic dissection is a condition in which there is an internal rupture of the innermost layers of the aorta that may form within the aneurysmal region. This represents a serious condition that precedes complete rupture of the aorta into the body space or into another organ such as the lungs or the trachea. One of the most serious types of rupture may occur within the pericardium (the membrane around the heart) in some patients. The resulting hemorrhage into the pericardial space impairs heart filling and can result in death unless surgical intervention is made. Therefore, the presence of a dissection flap in the proximal aorta is an indication for surgery regardless of the size of the aneurysm or the associated symptoms.

Most aneurysms do not have symptoms. Thus, they are commonly detected during the course of diagnosis for other conditions. For instance, thoracic aneurysms may be detected during a chest x-ray, and abdominal aortic aneurysms may be detected during an abdominal CT scan for a different reason.

However, if an aortic aneurysm is suspected, a physician will begin by asking questions about the patient’s medical history, which will include asking whether any of the patient’s relatives have a history of an aortic aneurysm. The physician will then perform a complete physical examination, which will include listening to the patient’s heart with a stethoscope, feeling the abdomen for a pulsating mass, taking the patient’s pulse and measuring the patient’s blood pressure.

If information from the medical history and physical examination suggest that an aortic aneurysm may be present, the physician will perform duplex ultrasound examinations of the abdominal aorta. This painless test uses sound waves to visualize the structures and functions of the aorta. It can provide visual images of an aortic aneurysm by placing a device called a transducer on the skin over the aorta. The resulting images can determine the location and size of an aortic aneurysm with a fairly high degree of accuracy.

A minimally invasive variation for the diagnosis of thoracic aortic aneurysm is the transesophageal echocardiogram, in which the transducer is inserted through the mouth/throat and down the esophagus. This positioning allows the transducer to capture clear images of certain types of thoracic aneurysms without interference from the chest wall or lungs.

Additional tests that may need to be done include:

Management of an aneurysm depends on the size of the aneurysm, its rate of expansion, the presence of other forms of heart disease, and the gender and age of the patient. In general, physicians will not recommend surgery for smaller aneurysms that have little risk of rupturing. Instead, antihypertensives to treat high blood pressure might be prescribed, especially beta blockers because they also decrease the force on the arterial wall. As a result, these medications may be able to slow the rate at which the aortic aneurysm expands. Other medications that may be prescribed include cholesterol-reducing drugs to lower cholesterol levels. Quitting smoking is also an important part of therapy.

If, however, the aneurysm is larger, has symptoms, or there are other factors that might increase the risk of rupture, surgery may be recommended. In 2005, the American College of Cardiology and American Heart Association (ACC/AHA) issued guidelines to help physicians decide when to perform surgery. The ACC/AHA recommended that aneurysms between 4 and 5.4 centimeters be monitored yearly by ultrasound or CT scanning, while aneurysms between 3 and 4 centimeters should be monitored by ultrasound every two to three years.

Traditional surgery requires the abdomen (or chest if the aneurysm is thoracic) to be opened surgically. The bulging section of the aorta is excised (surgically removed) and the remaining blood vessel reconnected using a synthetic graft. In recent years, this surgery has become quite safe, with a success rate of about 90 percent. Risks of surgery include kidney failure, infection, bleeding and formation of a false aneurysm.

Alternatively, a physician may use special stents called stent-grafts to repair abdominal aortic aneurysms. According to the American Heart Association, this option is generally recommended for patients who at high risk of surgical complications. Stent-grafts are not currently recommended for treatment of thoracic aortic aneurysms. During the stent-graft procedure (also known as endoluminal aortic stent-grafting or endovascular repair), the physician prevents blood from flowing through the aneurysm by placing one stent just above the aneurysm and a second stent just below the aneurysm. The two stents are connected by a tube of synthetic material (a graft), which provides a channel for blood to flow without entering the aneurysm. Because the grafts are delivered via a catheter, the use of grafts is less invasive than traditional surgery. And the grafts allow the aneurysm to be bypassed rather than removed, the procedure results in less trauma to the blood vessels.

The success rate of using stent-grafts to treat abdominal aortic aneurysms has risen to 90 percent, although the long–term safety of these devices is still unknown, and in recent years, several abdominal aortic aneurysm stent grafts were removed from the market. Complications with this procedure include the risk of blood leaking from the graft, known as endoleak. There are several types of endoleaks, the most serious being if the blood leaks into the aneurysm. This will increase the risk of rupture.

The root causes for many types of aneurysms are high blood pressure (hypertension) and hardening of the arteries caused by a buildup of fatty plaque along the arterial walls (atherosclerosis). Abdominal aortic aneurysms (AAAs) also run in families, and first-degree relatives of patients diagnosed with an AAA are urged to have a duplex ultrasound examination of their abdominal aorta. 

As with coronary artery disease, peripheral arterial disease and many other conditions, the goal of a preventive program is to keep blood pressure within a normal range and to reduce the likelihood of plaque buildup and calcification. Specific preventive strategies include:

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to aortic aneurysms:

1. Do you suspect there is an aneurysm in my aorta?
   
   
2. Where along my aorta is the aneurysm located?
   
   
3. How serious is my condition? How big is the aneurysm?
   
   
4. How urgently do I need to begin treatment for this condition?
   
   
5. Are there any tests I can take to give you a better idea of my condition?
   
   
6. Are there any underlying conditions causing the aneurysm?
   
   
7. What type of treatment do you recommend for my condition?
   
   
8. Will my condition require any type of surgery?
   
   
9. Are there any lifestyle changes I can make to improve my condition?
   
   
10. Can an aneurysm affect my pregnancy in any way?
    
    
11. How often should I have the growth of the aneurysm monitored?