Aneurysms and Dissections

An aneurysm is a balloon-like or bulge that can form in any artery. It is similar to an over-inflated inner tube, and occurs when the pressure of blood passing through a weakened artery causes it to bulge outward, forming what might appear as a blister. Not all aneurysms are life-threatening, but if the bulging stretches the artery too far, the vessel may burst, causing severe bleeding and, possibly, death. An aneurysm that bleeds into the brain can cause a stroke or death.

Where do aneurysms occur in the body?
• In the arteries that supply blood to the brain. This is called a cerebral aneurysm.
• In parts of the aorta. Aortic aneurysms occur below the stomach or kidneys (abdominal aortic aneurysm or “AAA”) or in the chest (thoracic aneurysm).
• In the left ventricle of the heart. A heart attack can damage the wall of the heart, making it thin and weak. When a ventricular aneurysm forms in the damaged area, the heart must work harder to pump blood to the rest of the body. Ventricular aneurysms can cause shortness of breath, chest pain, or an arrhythmia. Surgery may be necessary for a ventricular aneurysm that causes congestive heart failure, left ventricular heart failure, or arrhythmia.

How do aneurysms happen, and who is at risk?

Any condition that weakens the walls of the arteries can lead to an aneurysm. Increased risk has been associated with:

Atherosclerosis
Hypertension
• Smoking
• Deep wounds, injuries, or infections of the blood vessels
• A congenital abnormality
• Inherited diseases, such as Marfan syndrome

Diagnosis
Aneurysms are detected by physical examination, x-ray examination, or diagnostic ultrasound. An abdominal aortic aneurysm may be discovered by a physician who feels a pulsating bulge in the abdomen during a physical examination. The size and location can be found using echocardiography or diagnostic imaging, such as arteriography, magnetic resonance imaging (MRI), and computed tomography (CT) scanning.

Symptoms
Symptoms differ with the type and location of the aneurysm, and they appear when the aneurysm interferes with nearby organs, nerves, and blood vessels. For example:

• Aortic aneurysms may cause shortness of breath, a croaky or raspy voice, backache, or a broad range of shoulder-area pain.

• Abdominal aortic aneurysms may cause pain or tenderness below the stomach, loss of appetite, or upset stomach.

• Cerebral (brain) aneurysms may have no symptoms, or they may cause headaches, pain in the neck and face, or trouble seeing and talking.

Treatment
Treatment depends on the size and location of the aneurysm and the patient’s overall health. Aneurysms in the upper chest (the ascending aorta) usually undergo immediate surgery. Aneurysms in the lower chest and abdomen (the descending thoracic and abdominal aorta) may not be as life-threatening and are watched until they become 5 cm in diameter, continue to grow, or cause symptoms. At that time, surgery is necessary to prevent the aneurysm from bursting.

The surgery for aneurysms occurring in the peripheral vessels, which supply blood to the arms, legs, and head, involves replacing the weakened section of the vessel with an artificial tube called a graft. For abdominal aneurysms, a patch or artificial piece of blood vessel is used to replace the damaged area, reinforce the aorta, and prevent recurrence.

Smaller, stable aneurysms in the descending aorta or abdominal aorta are watched at regular intervals. An aneurysm that does not grow or worsen is left untreated. Medicines that lower blood pressure may be prescribed to relieve stress on the aortic walls. This type of medical treatment is especially useful for patients who are not good candidates for surgery.

A nonsurgical procedure is available to treat abdominal aortic aneurysms, and this technique is also useful for patients whose overall health is too poor to undergo surgery. The procedure uses a catheter to insert a device called a stent graft. The stent graft is placed within the artery at the site of the aneurysm. The blood flows through the stent graft, decreasing the pressure on the wall of the weakened artery and preventing the aneurysm from bursting. Benefits of the procedure include no general anesthesia, a shorter hospital stay (about 24 hours), faster recovery, and no large scars.
Dissections

Aortic dissection occurs when the layers of the wall of the aorta separate or are torn, allowing blood to flow between those layers and causing them to separate further. When the aortic wall separates, blood cannot flow freely, and the aortic wall may burst. Dissections can occur in the aorta and its main branches.

Dissecting aneurysms are usually diagnosed by the symptoms they produce. When examined, approximately two-thirds of patients with aortic dissection have diminished or no pulses in their arms and legs. A dissection that is moving backward toward the heart may cause a murmur that can be heard through a stethoscope. An aortic dissection may cause sudden and severe pain. Patients report feeling like something is ripping or tearing inside of them. The pain is mainly felt in the chest, but it can spread to the back or between the shoulder blades. Aortic dissection may also cause sudden stomach pain, lower back pain, or flu-like symptoms. If blood leaks from the dissection and builds up in the chest, it may pool around the heart and prevent it from working properly. This life-threatening condition is called cardiac tamponade.

Immediate surgery is usually necessary for patients with aortic dissection, especially if the dissection is close to the heart. Dissections occurring further from the heart can be treated with medicine (such as beta blockers to lower blood pressure) and watched closely. Surgery is needed if the dissection begins to leak blood, causes a blockage, or enlarges.


Resources
Texas Heart Institute www.texasheartinstitute.com/HIC/Topics/Cond/Aneurysm.cfm

MedlinePlus www.nlm.nih.gov/medlineplus/aneurysms.html
American Heart Association http://www.americanheart.org/presenter.jhtml?identifier=4455
Mayo Clinic www.mayoclinic.org/aortic-aneurysm