The 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) and is filled with oxygen-rich blood that travels throughout the body. The aorta itself goes from the heart, through the diaphragm, and 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, a pair of blood vessels that branch off into each leg.
The aorta is made up of:
- A thin inner layer called the intima
- 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. 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 aorta. If it bursts, blood can escape, creating a life-threatening situation.
Aneurysms can happen at any point along the aorta. When an aneurysm develops in the area of the aorta that descends from the chest into the abdomen it is known as a thoracoabdominal aortic aneurysm.
An aortic aneurysm is a progressive disease that will generally grow over time and may not have any symptoms (asymptomatic) in the beginning. As the aneurysm becomes larger, symptoms may vary depending where the aneurysm is located and what structures are nearby. These may include:
- Chest pain
- Back pain
- Hoarse voice
- Shortness of breath
- High-pitched breathing
- Swelling in the neck
- Rapid heart rate
- Clammy skin
Causes and Risk Factors
An aortic aneurysm can occur in patients of any age and gender; however, older men are more often diagnosed with the condition. The cause of aortic aneurysms is not completely understood, although known risk factors include:
- Tobacco use
- Hardening of the arteries (atherosclerosis)
- A connective tissue disease, such as Marfan syndrome
- Untreated infections such as syphilis or salmonella
- Traumatic injury
- Increased age
Patients with a family history of the condition have also been shown to be at an increased risk of developing aortic aneurysms.
Diagnosis of aortic aneurysms generally cannot be done with a physical exam unless the aneurysm has ruptured. However, the physician will take the patient's medical history and perform a physical exam to better understand the patient's overall health. Patients may also be asked if they have experienced any symptoms.
After the physical exam, the physician may order tests to examine the heart muscle, the blood flow through the heart, and any potential leaking within the heart valves. These tests may include:
- An echocardiograph, a noninvasive procedure that uses a machine called a transducer to transmit sound waves that bounce off the heart (echo) and back into the transducer. These echoes are then translated into visual images.
- Imaging tests such as a cardiac MRI or chest X-ray to see if the heart is enlarged (if the echocardiograph was inconclusive). If more detail is needed about the heart and its arteries, a coronary angiography may be used. This procedure provides a map of the heart and the blood vessels near it by injecting into the blood vessels a special dye that shows up on the X-ray.
- An electrocardiogram (EKG), a noninvasive procedure that may be used to examine the electrical activity of the heart. In some cases, it may be important to monitor the electrical activity over the course of an entire day. To do this, a portable device known as a Holter monitor is used.
- Blood tests, to rule out the possibility of an infection such as syphilis.
Treatment for an aortic aneurysm will depend on the aneurysm's size, and will focus on keeping it from rupturing.
For smaller aneurysms, the best course of treatment may involve observation and monitoring, with an echocardiogram every six months and possible medication if the patient has high blood pressure or high cholesterol levels. Medication may include beta blockers to slow the heartbeat and relax the heart muscle so that it can work more efficiently, and angiotensin II receptor blockers to lower blood pressure.
If the aneurysm is larger, or if the patient has a connective tissue disease, surgery may be needed to treat the condition. The type of surgery performed will depend on the location of the aneurysm and the patient's overall health. Possible surgeries include:
- Open-chest surgery, which repairs the area weakened by the aneurysm by replacing it with a graft made of a synthetic tube
- Endovascular surgery, which uses a catheter guided through the vein to place a tube at the weakened spot.
If the aortic aneurysm is caused by another condition, treatment may focus on the underlying condition. The knowledgeable and highly trained staff at the Cedars-Sinai Heart Institute will work with each patient to determine the best treatment option.