Aortic AneurysmThe aorta is the largest artery in the body. It rises from the heart's left ventricle (the major chamber that pumps blood out of the heart) filled with oxygen-rich blood that travels throughout the body.
The aorta itself goes from the heart through the diaphram into the abdomen. Many smaller vessels branch off from it. These branches bring blood to the kidneys and organs of the digestive system. The aorta divides into the iliac arteries. This is a pair of arteries that branch off into each leg. When the aorta becomes damaged or loses its ability to contract and relax as blood is pumped through it, an aneurysm can develop.
An aneurysm is a weakened spot in the walls of the vessel. If it bursts, blood can escape from the aorta, creating a life threatening situation.
Aneurysms can happen at any point along the aorta.
Structure of the Aorta
The walls of the aorta are made of three layers:
- A thin inner layer
- A thick, elastic middle layer called the media
- A thin outer layer called the adventitia
These layers allow the aorta to absorb the force of the blood as it is pumped from the heart to the rest of the body. The tissues of the aortic walls allow it to stretch under pressure. When the pressure passes, the walls relax.
Types of Aortic Aneurysms
Aortic aneurysms are described by:
- Where they are located along the aorta (such as on the root near the heart, ascending, arch, descending or in the area of the chest or abdomen)
- How big they are. This is usually measured in centimeters around the diameter of the widest part of the enlarged area.
- What shape they have: fusiform (below center), which is an area enlarged in all directions; or saccular (below right), which is a bulge or sac on one side of the aorta
An aortic aneurysm is often silent. If a tear is causing the aneurysm, a person may feel pressure or pain in the chest that radiates to the back.
Causes and Risk Factors
An aneurysm of the aorta may develop in several ways:
- Diseased aortic tissue causes the aorta's walls to become weak
- A tear in the aorta's inner walls lets blood leak into the middle layer of the wall, causing the layers to separate. This is called dissection or tear. If this happens where the aorta rises out of the heart (a Type A dissection), it is life threatening and requires emergency surgery. The aorta at that point has the most pressure on its walls and lacks support from nearby structures. If the tear occurs elsewhere along the aorta, it is called a Type B dissection. This type can be controlled with blood pressure drugs and regular monitoring. But if the flow of blood to the lower body is affected or blocked, surgery will be needed.
- Injury. This can happen when a person who is moving (as in a car, a major fall, a plane crash or a pedestrian accident) stops suddenly. The rapid change in speed can cause the two inner layers of the aorta to break. All that holds the vessel together is the thin outer layer.
- A lack of some or all of the aortic walls, usually due to an injury or infection of the inner aortic wall. These are called pseudoaneurysms or false aneurysms. They are more unpredictable and more likely to rupture than other types of aneurysms. Usually there is more swelling in the nearby tissue. This potentially6 can complicate a surgery. Pseudoaneurysms from an infection can cause embolisms or strokes.
When the weak spot in the aorta becomes enlarged, it is called ballooning or dilation. When the area gets to 4.0 centimeters in size, it is called an aneurysm. No matter how an enlargement of the aorta is defined or what its size is, it is a sign of disease and needs treatment. Any enlargement of the aorta needs to be watched.
People are different sizes so an aneurysm may be defined by how much larger the weak area of the aorta is compared to its normal size for that person. If the enlarged area is 1.5 to two times larger than the normal size of the blood vessel, it is defined as an aneurysm.
A person should be examined to see if he or she has an aortic aneurysm if he or she has:
- Pressure or pain in the chest that radiates to the back
- Been in a car accident that involved a vehicle rolling over, a fatality, being thrown from a vehicle, a dent of more than 12 inches in the vehicle or using the Jaws of Life to get out of the vehicle
- Been a pedestrian who was struck by a car going more than 20 m.p.h.
- Fallen from building, tree or other high place
- Marfan syndrome, Ehlers-Danlos syndrome, any connective tissue disorder that affects the heart, a bicuspid valve, atherosclerosis, or any type of infection or inflammatory condition that affects the heart and blood vessels
- High blood pressure
- Been a smoker
Aortic aneurysms are usually discovered during a routine physical examination or a test for another condition.
Diagnostic testing is the first step in establishing a treatment strategy. A doctor may order tests such as:
Other tests may include nuclear medicine (adenosine thallium myocardial viability tests) to see if there are any pre-existing coronary artery problems.
Treatment of an aneurysm will depend on how large it is and the person's general health, among other factors. It can range from lifestyle changes to surgery. Treatment usually includes some or a combination of the following:
- Managing blood pressure using drugs such as beta blockers, ACE-inhibitors, ARBs and calcium channel blockers or diuretics. Ideally, systolic blood pressure should range between 105 and 110 during normal activity
- Maintaining a healthy weight through a diet low in fat and high in fiber and protein
- Not smoking and not being around people who do
- Regular exercise, such as power walks of 15 to 30 minutes two to three times a day. Heavy lifting should be avoided because it puts pressure on the aorta.
- When the risk of a ruptured aorta is greater than the risk of surgery, surgery is done to replace the diseased section of the aorta with a Dacron graft. If necessary, the aortic valve may be either repaired or replaced.
After treatment, it is necessary to maintain a healthy blood pressure, an optimum weight, get regular exercise and eat a healthy diet.
A CT scan or MRI is done following surgery and then at regular periods after that. Echocardiography is used to make sure that the heart and valves are functioning correctly. Good dental and oral hygiene, including regular cleanings and examinations, are strongly recommended to minimize the risk of an infection spreading from the mouth to the heart or heart valves.