Definition
Figure 1. The Abdominal Aorta
and Its Branches
Figure 2. A Typical Aortic Aneurysm
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. (Figure 1)
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 twice its normal size it is abnormal, potentially dangerous and is considered an Abdominal Aortic Aneurysm (AAA). (Figure 2)
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 50-90%, and survivors frequently suffer serious complications.
Causes
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 AAA’s include:
- High blood pressure
- Smoking tobacco
- High blood cholesterol
Major risk factors for AAA include:
- Male
- Age over 60 years
- High blood pressure
- Smoking
- A family history of AAA
Warning Signs
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.
Prevention
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.
- 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, 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.
Treatments
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
- Radiologic Imaging Studies:
- CT (computerized tomography)
- 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 5 cm in diameter) grow rapidly and require surgical or interventional (endovascular) treatment.
Figure 3. Aortic Graft Replacement
Figure 4. Endovascular Aneurysm Repair
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 (usually Dacron or Teflon) that is carefully matched to the size of the normal aorta sewn in place by the surgeon. (Figure 3)
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. (Figure 4)
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.
What is VascularCures doing about it?
VascularCures supports the work of Timothy Chuter, MD and Darren Schneider, MD, who are leaders in treating abdominal aneurysms and using stent technology. Their research involves developing less invasive surgical methods.
Recent research in animals indicates certain drugs can counteract inflammatory damage in developing aneurysms, and thus reduce an aneurysm’s rate of expansion. One of these drugs is now being tested to determine whether it slows the expansion of small aneurysms in humans. This holds great promise, but large aneurysms will likely continue to require surgical or endovascular repair. Robert Thompson, MD, VascularCures' first Wylie Scholar, has been working on medication to reduce the rate of aneurysm expansion.