Thoracic aortic aneurysm resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:

Synonyms and keywords:

Overview

• Thoracic aortic aneurysm is a permanent localized thoracic aortic dilatation that has at least a 50% diameter increase and three aortic walls. its shape could be fusiform or saccular.
• Classification:
• Above the ligamentum arteriosum, the disease is not related to typical arterial risk factors and has a smooth, noncalcified wall accompanied by no debris or clot.
  • Aortic root aneurysm(60% of TAA occurs in the aortic root and/or ascending aorta)
  • Ascending aortic aneurysm
  • Aortic arch aneurysm(10% occur in the aortic arch)
  • Descending aortic aneurysm (at the level of the ligamentum arteriosum, just distal to the origin of the subclavian artery,40% of TAA occur in the descending aorta), the disease process primarily is atherosclerotic, with an irregular calcified wall accompanied by copious debris and clot
  • thoracoabdominal aorta (10% of TAA occur in the thoracoabdominal aorta, based on Crawford classification, there are 5 types of thoracoabdominal aortic aneurysm: I II III IV V)

patients are usually asymptomatic and diagnosed during imaging studies done for another diagnostic reason.If its symptomatic, symptoms could be due to aneurysmal dissection, rupture, or bony erosion, or due to mass effect from a large thoracic aortic aneurysm, presents with Hoarseness (recurrent laryngeal nerve), dyspnea (trachea, mainstem bronchus, pulmonary artery), central venous hypertension (superior vena cava syndrome), dysphagia (esophagus), Rupture of thoracic aortic aneurysms (rupture of an ascending aortic aneurysm may cause cardiac tamponade, a rupture in the descending thoracic aorta may cause hemothorax, aortobronchial fistula, or aortoesophageal fistula)

• If there are symptoms suggesting thoracic AA expansion, surgical intervention should be considered.
• If the ascending thoracic aorta or aortic sinus diameter is 5.5 cm or more in an asymptomatic surgical candidate who has a degenerative thoracic AA, chronic aortic dissection, intramural hematoma, penetrating atherosclerotic ulcer, mycotic aneurysm, or pseudoaneurysm, surgery should be performed.
• Asymptomatic persons with genetic conditions such as Marfan's syndromes should have elective surgery if their diameters are 4.0 to 5.0 cm depending on the disorder to prevent acute dissection or rupture.
• Asymptomatic persons with Marfan’s syndrome should be treated with surgical intervention if their ascending thoracic aortic diameter is 5.0 cm or more and with <5.0 cm if there is a family history of dissection or an increase in ascending thoracic aortic diameter greater than 0.5 cm per year.
• Asymptomatic persons who have Loeys-Dietz syndrome should be treated with surgical intervention if their ascending thoracic aortic diameter is ≥4.2 cm by transesophageal echocardiography or 4.4 to

4.6 cm by cardiac computed tomography or cardiac magnetic resonance

• If the increase in the ascending thoracic aortic diameter is greater than 0.5 cm per year in an asymptomatic person with a diameter below 5.5 cm, surgical intervention should be performed.
• Asymptomatic persons with bicuspid aortic valve should have surgical intervention if the diameter of their aortic sinuses or ascending thoracic aorta is >5.5 or >5.0 cm with a family history of aortic dissection or an increase in diameter ≥0.5 cm/year
• The ascending thoracic aorta should be replaced in persons with bicuspid aortic valve having aortic valve surgery if their ascending thoracic aorta diameter is >4.5 cm

Causes

Life Threatening Causes

• Aortic dissection

Common Causes

• Causes:
  • Arteriolosclerosis &Hypertension
  • Aging
  • Smoking
    
  • Genetic inheritance(with mutations in genes such as FBN1, TGFBR1, TGFBR2, ACTA2, and MYH11)
    
  • Inflammatory causes(Syphilis,Mycotic aneurysm from endocarditis,Giant-cell arteritis,Takayasu arteritis)
    
  • Trauma
  • Connective tissue; Marfan’s (young), Loeys-Dietz syndrome, Ehler Danolsor other connective tissue diseases, Turner syndrome
    
  • Known aortic valve disease e.g.Bicuspid AV
  • Family history of aortic disease
  • Recent aortic manipulation (surgical or catheter-based)

Screening

• Screening for TAA is not recommended in the general population.However, certain population substrates, such as those with history of marfan's syndrome, turner's syndrome, ehlers-danlos type IV syndrome, familial thoracic aortic disease syndromes, bicuspid aortic valve, takayasu arteritis, giant cell arteritis, loeys-dietz syndrome or a confirmed genetic mutation known to predispose to aortic aneurysms and aortic dissections (TGFBR1, TGFBR2, FBN1, ACTA2, or MYH11) should have imaging study to screen for TAAs.

Marfan's syndrome

I	IIa	IIb	III
C

An echocardiogram is recommended at the time of diagnosis of Marfan syndrome to determine the aortic root and ascending aortic diameters and 6 months thereafter to determine the rate of enlargement of the aorta.

Annual imaging is recommended for patients with Marfan syndrome if stability of the aortic diameter is documented. If the maximal aortic diameter is 4.5 cm or greater, or if the aortic diameter shows significant growth from baseline, more frequent imaging should be considered.

Loeys-Dietz syndrome

I	IIa	IIb	III
C

Patients with Loeys-Dietz syndrome or a confirmed genetic mutation known to predispose to aortic aneurysms and aortic dissections (TGFBR1, TGFBR2, FBN1, ACTA2, or MYH11) should undergo complete aortic imaging at initial diagnosis and 6 months thereafter to establish if enlargement is occurring.

Patients with Loeys-Dietz syndrome should have yearly magnetic resonance imaging from the cerebrovascular circulation to the pelvis.<ref

Turner syndrome

I	IIa	IIb	III
C

Patients with Turner syndrome should undergo imaging of the heart and aorta for evidence of bicuspid aortic valve, coarctation of the aorta, or dilatation of the ascending thoracic aorta.

Screening of family members

First-degree relatives of people with thoracic aortic aneurysm or dissection should have aortic imaging to identify asymptomatic disease. Patients with high-risk syndromes such as Marfan's syndrome and loeys-dietz syndrome should undergo complete aortic imaging at initial diagnosis and 6 months thereafter to establish if enlargement is occurring.

I	IIa	IIb	III
	B

Sequencing of the ACTA2 gene is reasonable in patients with a family history of thoracic aortic aneurysms and/or dissections to determine if ACTA2 mutations are responsible for the inherited predisposition.

I	IIa	IIb	III
	B

Sequencing of other genes known to cause familial thoracic aortic aneurysms and/or dissection (TGFBR1, TGFBR2, MYH11) may be considered in patients with a family history and clinical features associated with mutations in these genes.

I	IIa	IIb	III
		C

If one or more first-degree relatives of a patient with known thoracic aortic aneurysm and/or dissection are found to have thoracic aortic dilatation, aneurysm, or dissection, then referral to a geneticist may be considered.

Treatment

• Once aortic dilation is suspected, based on echocardiography and/or chest X-ray, it is reasonable to obtain definitive aortic imaging with CT or magnetic resonance angiography. If the aneurysm is too small to justify surgery, non-surgical medical therapy is recommended, then repeat imaging at six months to document stability. If the aortic dimensions remain stable, annual follow-up with CT or MRA is reasonable. If a significant size has been reached or growth has been documented, they may elect to undergo surgical repair. however, it is beneficial to have early discussions with the potential surgical candidate about the area of concern and the types of operations available, their outcomes, and associated risks and benefits.

• patients with thoracic AA must be counseled about smoking cessation.
• Dyslipidemia must be treated. Atorvastatin 40 to 80 mg daily or rosuvastatin 20 to 40 mg daily should be administered
• Hypertension must be controlled with beta-blocker plus an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker these in these patients. The blood pressure in persons with thoracic AA should be lowered to less than 130/80 mmHg.

Do's

• The content in this section is in bullet points.

Don'ts

• The content in this section is in bullet points.