The Exchange

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<a href='/the-exchange/thoracic-aortic-aneurysm-part-1-'>Thoracic Aortic Aneurysm (Part 1)</a>

Thoracic Aortic Aneurysm (Part 1)

Thoracic aortic aneurysms (TAA) are located above the diaphragm, may involve one or more aortic segments (aortic root, ascending aorta, arch, or descending aorta), and are classified accordingly. When aneurysms are located under the diaphragm, they are classified as abdominal. Abdominal aneurysms are much more prevalent than TAAs. About 80% of aortic aneurysms occur between the renal arteries and the aortic bifurcation.

TAAs can be due to one of several etiologies. The natural history of TAA is one of progressive expansion, the rate of which depends upon the location of the aneurysm and its underlying cause. TAAs are rare, occurring in approximately 6 to 10 people per every 100,000, and about 20% of those cases are linked to family history. Although most TAAs produce no symptoms, patients who become symptomatic or have complications related to the aneurysm (eg, acute aortic regurgitation, dissection, aortic rupture) should undergo repair.

Although TAA is often a late-onset disease, a significant proportion of patients who present with TAA are less than 60 years of age. Cases of aortic aneurysms in young adults (20s and 30s) and children have also been reported; however, they are very rare. In this younger age group, a genetic predisposition is surmised. In the absence of an identifiable genetic syndrome, familial aggregation of these aneurysms is well established. The first-degree relatives of an individual with an aortic aneurysm have a ten- to twelve-fold increased risk of developing aortic aneurysms.

The factors that contribute to an aneurysm’s development are:

  • Atherosclerosis: hypertension and high cholesterol are well-known risk factors for atherosclerosis. This is more common in older people.
  • Genetic conditions:
    • Marfan syndrome, a genetic condition that affects the connective tissue in the body, places patients particularly at risk for TAAs.
    • Ehlers-Danlos, Loeys-Dietz, and Turner syndromes, along with other family-related disorders, can cause an aortic aneurysm. Ehlers-Danlos syndrome causes the skin, joints, and connective tissue to be fragile and makes the skin stretch easily.
  • Miscellaneous conditions: inflammatory conditions such as giant cell arteritis and Takayasu arteritis may cause TAA.
  • Aortic valve problems: people who were born with a bicuspid aortic valve are at an increased risk for TAA.
  • Untreated infections: though rare, it is possible to develop TAA if a patient has had an untreated infection, such as syphilis or salmonella.
  • Traumatic injury: though rare, some people who are injured in falls or motor vehicle crashes develop TAAs.
  • Smoking
  • Illicit drug use

We should always keep in mind that TAA is a possible diagnosis even in the young population. Although it is not frequent, assessing risk factors and high-risk clinical features for this condition should be done promptly in a patient complaining of acute chest or abdominal pain in order to conduct an appropriate evaluation, because of the fatalities associated with TAA if it is not treated quickly.

In the second part of this segment, which will be released later this week, I will go over the most common symptoms and those that are commonly missed.

References
  • Bickerstaff LK, Pairolero PC, Hollier LH, et al. Thoracic aortic aneurysms: a population-based study. Surgery. 1982;92:1103.
  • Clouse WD, Hallett JW Jr, Schaff HV, et al. Improved prognosis of thoracic aortic aneurysms: a population-based study. JAMA. 1998;280:1926.
  • Pressler V, McNamara JJ. Aneurysm of the thoracic aorta. Review of 260 cases. J Thorac Cardiovasc Surg. 1985;89:50.

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