A thoracic aortic aneurysm is an aortic aneurysm

Aortic aneurysm

An aortic aneurysm is a general term for any swelling of the aorta to greater than 1.5 times normal, usually representing an underlying weakness in the wall of the aorta at that location...

 that presents primarily in the thorax.

It is less common than an abdominal aortic aneurysm

Abdominal aortic aneurysm

Abdominal aortic aneurysm is a localized dilatation of the abdominal aorta exceeding the normal diameter by more than 50 percent, and is the most common form of aortic aneurysm...

. However, a syphilitic aneurysm is more likely to be a thoracic aortic aneurysm than an abdominal aortic aneurysm.

Age

The diagnosis of thoracic aortic aneurysm usually involves patients in the 6th and 7th decades of life.

Aneurysms in patients younger than 40 usually involve the ascending aorta due to a weakening of the aortic wall associated with connective tissue disorders like the Marfan and Ehler-Danlos syndromes or congenital bicuspid aortic valve. Younger patients may develop aortic aneurysms of the thoracoabdominal aorta after an aortic dissection.

Atherosclerosis is the principal cause of descending aortic aneurysms, while aneurysms of the aortic arch may be due to dissection, atherosclerosis or inflammation.

Risk factors

Hypertension and cigarette smoking are the most important risk factors, though the importance of genetic factors has been increasingly recognized. Approximately 10% of patients may have other family members who have aortic aneurysms. The principal causes of death due to thoracic aneurysmal disease are dissection and rupture. Once rupture occurs, the mortality rate is 50–80%, and most deaths in patients with the Marfan syndrome are the result of aortic disease.

Treatment

It is sometimes treated with surgery.

Indication for surgery may depend upon the size of the aneurysm. Aneurysms in the ascending aorta

Ascending aorta

The ascending aorta is a portion of the aorta commencing at the upper part of the base of the left ventricle, on a level with the lower border of the third costal cartilage behind the left half of the sternum; it passes obliquely upward, forward, and to the right, in the direction of the heart’s...

 may require surgery at a smaller size than aneurysms in the descending aorta

Descending aorta

The descending aorta is part of the aorta, the largest artery in the body. The descending aorta is the part of the aorta beginning at the aortic arch that runs down through the chest and abdomen. The descending aorta is divided into two portions, the thoracic and abdominal, in correspondence with...

.

Anesthesia management for surgical repair

Some concerns:
Placement of the arterial line should be on the right side
If the aortic cross-clamp is placed proximal to the left subclavian artery, flow to a left radial arterial line could be compromised. A femoral arterial line can be placed to monitor distal aortic perfusion if left heart bypass is used.

Antifibrinolytic therapy
If the aorta is cross-clamped above the celiac artery, primary fibrinolysis can develop and coagulopathy can then occur. Antifibrinolytic therapy seems logical, though its efficacy has not yet been proven.

How can the kidneys be protected?
Techniques used for kidney protection include maintenance of distal aortic perfusion during aortic cross clamping and infusing the renal arteries with cold perfusate during ischemia. Neither mannitol nor dopamine has been shown to reduce the incidence of postoperative renal dysfunction.

How can paraplegia incidence be reduced?
Paraplegia incidence, which ranges from 2.7-20%, can be reduced by CSF drainage, mean arterial pressure maintenance, left heart bypass, hypothermia and reimplantation of intercostal/radicular arteries. No single method is entirely effective. Also see the discussion above concerning reimplantation of the artery of Adamkiewicz. Consideration of paraplegia is important, not only because of its significant morbidity but also because it is associated with increased mortality.

This was discussed in more detail in a review article and also on that journal's blog.

Epidemiology

Each year in the United States, some 45,000 people die from diseases of the aorta and its branches. Acute aortic dissection, a life-threatening event due to a tear in the aortic wall, affects 5 to 10 patients per million population each year, most often men between the ages of 50 and 70; of those that occur in women younger than 40, nearly half arise during pregnancy. The majority of these deaths occur as a result of complications of thoracic aneurysmal disease.

Guidelines

Guidelines were issued in March 2010 for diagnosis and management of thoracic aortic disease, by the American College of Cardiology, the American Heart Association, and other groups. Among the recommendations:

• First-degree relatives of people with thoracic aortic aneurysm or dissection should have aortic imaging to identify asymptomatic disease.
• People with symptoms suggestive of thoracic aortic dissection should be routinely evaluated "to establish a pretest risk of disease that can then be used to guide diagnostic decisions."
• People diagnosed with Marfan syndrome should immediately have an echocardiogram to measure the aorta, and followed up 6 months later to check for aortic enlargement.