Dr Melas Nikolaos Vascular & Endovascular Surgeon MD, MSc, PhD

A thoracic aortic aneurysm is an aortic aneurysm that presents primarily in the thorax. It is less common than an abdominal aortic aneurysm. However, a syphilitic aneurysm is more likely to be a thoracic aortic aneurysm than an abdominal aortic aneurysm.

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.

Causes

Atherosclerosis is the principal cause of descending aortic aneurysms, while aneurysms of the aortic arch may be due to dissection, atherosclerosis or inflammation. It can be also caused by blunt injury. 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.

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. It is also important to note that individuals with a history of aneurysms in other parts of the body have a higher chance of developing a thoracic aortic aneurysm.

Screening

Guidelines were issued in March 2010 for early detection 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.

Treatment

The size cut off for aortic aneurysm is crucial to its treatment. A thoracic aorta greater than 4.5 cm is defined as aneurysmal, while a size greater than 6 cm is the distinction for treatment, which can be either endovascular or surgical, with the former reserved for pathology at the descending aorta.

Indication for surgery may depend upon the size of the aneurysm. Aneurysms in the ascending aorta may require surgery at a smaller size than aneurysms in the descending aorta

Complications

The principal causes of death due to thoracic aneurysmal disease is 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.