Aortic Aneurysms
The aorta is the largest blood vessel in the body. It originates just above the aortic valve and is shaped like a candy-cane; it rises vertically in the front of the chest, then curves at the top, then descends through the back of the chest into the abdomen before it divides into the arteries to the legs. In the chest, there are four major divisions.
- Aortic root: The part of the aorta just immediately above the aortic valve, which gives off the coronary arteries
- Ascending aorta: The portion in the front of the chest that courses upwards
- Arch: The portion curving at the top is called the arch. This gives off the branches to the arms and the brain.
- Descending aorta: The portion in the back going down is called the descending aorta.
An aneurysm is a dilated blood vessel, like a balloon. Aortic aneurysms can affect any portion of the aorta or any combination of portions of the aorta. There are a variety of causes of aortic aneurysms:
- Arteriosclerosis: Hardening of the arteries
- Cystic medial necrosis: A weakening of the tissues
- Hereditary conditions: Such as Marfan's disease
- Infections: Such as syphillis
When the aneurysm being discussed is in the chest, it is called a thoracic aortic aneurysm, and when it is in the abdomen it is called an abdominal aortic aneurysm. This website is devoted primarily to valvular heart disease, which is sometimes associated with aneurysms of the ascending aorta and arch, and the treatment of those aneurysms is largely surgical in nature. We will not be discussing aneurysms of the descending thoracic aorta or abdominal aorta.
Symptoms
The vast majority of aortic aneurysms cause no symptoms until they rupture. Most are detected on routine examination or chest X-rays or CAT scans done for other reasons.
- Chest pain: When an aneurysm is expanding or rupturing
- Aortic dissection: Many aneurysms do
not “pop” just like a balloon, but rather develop a tear in the wall of the
aorta. Rather than blood
leaking outside the aorta like air leaving a balloon, the blood flows through
the tear in the wall of the aorta into the wall itself. This disrupts
the layers of the aortic wall. Many life-threatening complications can
occur from this, and usually this is a surgical emergency. When a dissection
occurs, the blood flowing into the wall of the aorta creates a false channel.
The following complications of a dissection may occur:
- Rupture
- Tamponade: If the rupture occurs in the ascending aorta, blood then collects within the sac surrounding the heart, compressing the heart and squeezing it so it cannot fill. The sac around the heart is known as the pericardium, and this squeezing and compression of the heart is known as tamponade.
- Acute aortic valve insuffiencey: The dissection can also tear into the aortic valve, causing it to leak.
- Heart attack: The dissection can tear into a coronary artery.
- Neurologic problems: The dissection can also tear into other blood vessels, causing a stroke or loss of circulation to the limbs or organs.
Diagnosis
An ascending or arch aneurysm is usually detected as mentioned above. It may be seen on an echocardiogram, an ultrasound examination of the heart. The usual evaluation is with a CAT scan or MRI. A cardiac catheterization can detect blockages in the heart arteries and dye injected into the aorta will display the aneurysm.
Medical Treatment
There is no medical treatment of aortic aneurysms.
Surgical Treatment
- Indications: The indications for surgery are based on weighing the risks of the surgery versus the risks of rupture or dissection of the aneurysm. The risks of the aneurysm are related to its size. Generally, surgery is recommended when the aorta is greater than or equal to 5.5 cm. However, if the patient has to have heart surgery for other reasons, most surgeons will remove the dilated aorta if it is greater than or equal to 4.5 cm.
- Early Surgery: There are two circumstances
where surgery is indicated before the aneurysm reaches these
sizes.
- Marfan's disease (a hereditary condition) who are very likely to develop dissections
- Patients who had a close relative who developed a dissection.