- Clinical science
Thoracic aortic aneurysm (TAA) is the focal dilatation of the thoracic aorta to more than 1.5 times its normal diameter. TAAs are classified by location as affecting the ascending aorta, descending aorta, or aortic arch. Men of advanced age are at a higher risk of forming TAAs; other risk factors include trauma, connective tissue disorders, and hypertension. TAAs are frequently asymptomatic and therefore detected incidentally. If symptomatic, they may manifest with a feeling of pressure in the chest, thoracic back pain, and signs of mediastinal obstruction (e.g., difficulty swallowing). The initial test is often a chest x-ray, which may show a prominent aortic arch. CT with contrast is used to confirm the diagnosis and determine the extent of the aneurysm. Observation, close follow-up, and reduction of cardiovascular risk factors are indicated for small aneurysms whereas pronounced or rapidly expanding aneurysms require surgery. TAA rupture and dissection are life-threatening conditions that require emergency surgical repair to prevent cardiac tamponade, hemothorax, and death.
- Less common than ( )
- Peak incidence: 60–65 years
- Sex: ♂ > ♀ (∼ 3:1)
Epidemiological data refers to the US, unless otherwise specified.
- Advanced age
- Arterial hypertension
- Tertiary (due to obliterative endarteritis of the vasa vasorum) 
- Connective tissue diseases (e.g., Marfan syndrome, Ehlers-Danlos syndrome)
- Bicuspid aortic valve 
- Positive family history
- Rare: vasculitis/infectious diseases with aortic involvement (e.g., Takayasu arteritis)
- Ascending thoracic aortic aneurysm: most often due to cystic medial necrosis
- Descending thoracic aortic aneurysm: typically a result of atherosclerosis
- Inflammation and proteolytic degeneration of connective tissue proteins; and/or smooth muscle cells in high-risk patients → loss of structural integrity of the aortic wall → widening of the vessel
- The aneurysmatic dilatation of the vessel wall may cause disruption of the laminar blood flow and turbulence.
- Possible formation of thrombi in the aneurysm → peripheral thromboembolism
Aortic aneurysms are mostly asymptomatic or have nonspecific symptoms. They are often disovered incidentally on imaging.
- Chest pressure
- Thoracic back pain
- Features of mediastinal compression/obstruction, such as:
- Indications: may be conducted as an initial imaging study in patients with chest pain and/or dyspnea
- Suggestive findings 
CT angiography chest
- Indications: best confirmatory test for TAAs
Supportive findings 
- Dilatation of the aorta 
- Possible mural thrombus (nonenhancing)
- Possible dissection, perforation, or rupture
MR angiography chest with and without IV contrast
- Indication: Consider as an alternative to CTA. 
- In stable patients who should avoid ionizing radiation
- For serial follow-ups
- Supportive findings: similar to CTA
- Prolonged duration
- Less accurate than CTA in allowing for the visualization of branch vessel involvement 
- Indication: Consider as an alternative to CTA. 
- Transthoracic echocardiography 
Transesophageal echocardiography: allows for more accurate assessment than TTE 
- Indication: intraoperative monitoring
- Less accurate than CTA in allowing for the visualization of branch vessel involvement
- Limited visualization of pathologies above the gastroesophageal junction
Catheter angiography (aortography) 
- Evaluation and possibly treatment of coexisting coronary artery disease
- Assessment of aortic lumen and branch vessels
- Supportive findings: contrast column in the lumen of the aneurysm
- See “ .”
The differential diagnoses listed here are not exhaustive.
- Unstable patients (e.g., in the case of rupture): emergency TAA repair (see “Thoracic aortic aneurysm rupture”)
- Symptomatic patients: urgent TAA repair
- Asymptomatic patients
- All patients: conservative management with reduction of cardiovascular risk factors
Invasive treatment: TAA repair 
- TAA rupture
- Symptomatic TAA
- Asymptomatic TAA when size or growth thresholds are passed
Indications for asymptomatic patients
The decision to perform elective TAA repair in asymptomatic patients depends on the size and expansion rate of the aneurysm. In all patients, the risks and benefits of aneurysm resection should be weighed carefully. 
|Indications for TAA repair in asymptomatic patients |
|Affected location of the aorta||Aortic diameter|
|Aortic arch (isolated)|| |
|Descending aorta|| |
Open surgical repair (OSR) is recommended for patients with TAA of the ascending aorta and aneurysms involving the aortic arch. For patients with descending thoracic or thoracoabdominal aortic aneurysms, thoracic endovascular aneurysm repair (TEVAR) or OSR can be performed.
Open surgical repair (OSR) 
- Indications: preferred in young patients with few comorbidities and low surgical risk and patients with connective tissue disorders 
- Complications: 40% of all patients experience a perioperative complication 
- Indications: Degenerative or traumatic descending aortic aneurysms
- Absence of a sufficiently long (2–3 cm) “landing zone” for the stent graft
- Absence of adequate vascular access sites
- Procedure: Under fluoroscopic guidance, an expandable stent graft is placed via the femoral or iliac arteries intraluminally at the site of the aneurysm.
- Complications 
- Other: requires lifelong postoperative surveillance
Concomitant diseases may require additional procedures, e.g., CABG, valve replacement or repair.
- See “ .”
Surveillance after repair 
All patients should receive conservative treatment to reduce the risk of further aneurysm expansion or rupture. Regular aneurysm surveillance via CT or MR is recommended for patients in whom the diameter of the aneurysm has not reached the threshold defined as the indication for repair.
Reduction of cardiovascular risk factors 
Blood pressure management
- Optimal blood pressure goal to reduce aortic wall stress: the lowest blood pressure that the patient can tolerate 
- Preferred agents:
- Smoking cessation
- Lipid profile optimization: in patients with atherosclerotic aortic aneurysms
Lifestyle modification 
- No participation in most competitive sports
- No heavy weight lifting
|Part of the aorta||Maximum diameter of the aorta||Recommended follow-up interval|
|Ascending aorta|| || |
| || |
|Aortic arch|| || |
| || |
|Descending aorta|| || |
| || |
Risk factors 
Clinical features 
- Contained rupture
- Free rupture
Hemodynamically unstable patients: no time for detailed assessment
- Proceed directly to OR and consider bedside TTE.
- Hemodynamically stable patients: Obtain CTA of the chest, abdomen, and pelvis with IV contrast.
- Hemodynamically unstable patients: no time for detailed assessment
Additional diagnostic evaluation to consider (once patient has been stabilized)
- ECG: to rule out STEMI as a differential diagnosis
- Laboratory studies: There are no laboratory findings specific to TAA rupture.
- See “Chest pain” for workup and differential diagnoses.
- Surgery consult
- IV access with two large-bore peripheral IV lines
- Check CBC, type and screen, obtain patient consent for blood transfusion, and order pRBCs (prepare for massive transfusion protocol).
- IV fluid resuscitation
- Pain management