Aneurysms are bulges that occur in weakened regions of the wall of an arterial blood vessel. The most common and serious aneurysms occur in the aorta, the main artery that carries oxygen-rich blood from the heart through its branches to the entire body.
The majority of aortic aneurysms occur in the abdominal region below the diaphragm. They are caused by a weakening of the aortic wall. When the diameter of a region of the aorta enlarges more than 50% its normal size or greater than three centimeters, it is abnormal, potentially dangerouus, and is considered an Abdominal Aortic Aneurysm (AAA).
Like a balloon, a weakened aorta enlarges slowly at first from the pressure within it, but the larger it gets the more rapidly it grows until it eventually bursts. The mortality from ruptured aortic aneurysms is 50 to 90%, and survivors frequently suffer serious complications. With the aging of our population, the incidence of AAA has tripled during the last 40 years. Most occur in men over 65 years, where aneurysms are four times more common than in women.
Abdominal Aortic Aneurysms are mainly caused by damage to the wall of the blood vessel. Several factors may cause inflammation of the aortic wall (including high blood pressure). The inflammation causes a breakdown of tissue and weakening of the arterial wall, which allows it to “balloon.”
If high blood pressure is not brought under control, it will continue to weaken the arterial wall, and cause the aneurysm to grow larger. Eventually, the arterial wall will rupture and create an emergency, life-threatening situation.
The primary causes of AAAs include:
- High blood pressure
- Smoking tobacco
- High blood cholesterol
Major risk factors for AAA inclue:
- Age over 60 years
- High blood pressure
- Elevated cholesterol
- A family of AAA
It is estimated that of the 1.5 million Americans with an AAA, only 200,000 have been diagnosed. This is because many AAA’s are small and cause no symptoms.
Most aneurysms show no symptoms, although some patients may be aware of abnormal pulsation in the mid-abdomen. A rapidly growing aneurysm that may soon rupture can cause pain in the back or abdominal region, sometimes with bloating or nausea and vomiting.
If the aneurysm ruptures, a person will show the sudden signs of shock due to excessive bleeding – dizziness or fainting with weakness, sweating, rapid heart beat, and loss of consciousness.
Ruptured aneurysms annually kill more than 15,000 Americans and are the 13th leading cause of death in the United States.
There are several things a person can do to help prevent the development of an AAA:
- Stop smoking. Smoking damages blood vessels. Nicotine causes blood vessels to constrict and blood pressure to rise. It also slows a damaged vessel’s ability to heal itself. Smoking cessation is the most powerful modifiable risk factor.
- Control blood pressure. Hypertension makes the heart work harder as it pushes blood through the arteries, putting more pressure on the walls of the vessels. It can also speed ballooning or dilation of a small weakened aortic wall, causing the aneurysm to grow larger.
- Watch your diet and maintain a normal weight. Fatty and cholesterol-laden foods can increase the amount of plaque buildup in your arteries. Avoid foods high in sodium (salt), because they can increase your blood pressure. Replace fatty, cholesterol-laden and salty foods with low or nonfat unsalted dairy products, fresh vegetables and fruit, salt substitutes, baked, and broiled or steamed foods.
- Control cholesterol. If dietary measures are insufficient, your doctor may prescribe medications to lower cholesterol and reduce plaque growth.
- Develop and continue an exercise program.
One of the important reasons your doctor examines your abdomen during a routine physical examination is to feel for an abnormally pulsating aorta in the mid-abdominal region. This can reveal a significant, although silent, aneurysm in more than one-half of affected patients.
If an aneurysm is discovered, or suspicious symptoms are present, your doctor can schedule more specific tests, such as:
- Ultrasound examination
- CT (computerized tomography) scan
- MRI (magnetic resonance imaging)
- Arteriography (injection of contrast dye coupled with x-rays) to identify the location, size, and extent of the aneurysm
Because smaller aneurysms grow slowly, they can be observed over a period of time before treatment is required. Larger aneurysms (more than five centemeters in diameter) grow rapidly and require surgical or interventional (endovascular) treatment.
There are two primary treatments for AAA. The first, open surgical repair of an AAA, has been used for over 50 years. It remains a very successful procedure. The diseased part of the aorta is replaced with a synthetic graft that is carefully matched to the size of the normal aorta and sewn in place by the surgeon.
The second, endovascular repair, has been developed in the last decade as a less invasive repair. It was approved by the Federal Food and Drug Administration in 1999. During this process a “stent” graft is inserted through an artery in the groin and delivered to the aneurysm via a catheter. Guided by x-ray images, the graft is positioned and secured to exclude the anuerysm.
The endovascular method is preferred for patients considered to be a high risk for open surgery repair. Traditional surgery, with its documented durability, is used for many patients, and for all those whose aneurysm cannot be treated by a stent graft.