Thoracic Aortic Aneurysm

What a thoracic aortic aneurysm is

The aorta leaves the heart, rises (ascending aorta), curves over (arch), and runs down through the chest (descending thoracic aorta) before entering the abdomen. A normal ascending aorta in adults is usually under about 4 cm wide, depending on body size, age and sex. When a segment widens to about 1.5 times normal, it is called an aneurysm; smaller increases are often described as dilation or ectasia.

For aneurysms below the diaphragm, see abdominal aortic aneurysm, and for the overview of both, aortic aneurysm.

Causes and risk factors

• Age and high blood pressure: the most common contributors, causing gradual weakening of the aortic wall.
• Genetic aortic conditions: Marfan syndrome, Loeys-Dietz syndrome, vascular Ehlers-Danlos syndrome, and familial thoracic aortic aneurysm (about 1 in 5 people with a TAA has an affected relative).
• Bicuspid aortic valve: a valve with two leaflets instead of three, present in 1% to 2% of people, often linked to ascending aorta enlargement.
• Turner syndrome.
• Atherosclerosis and smoking, mainly for descending aneurysms.
• Inflammation: giant cell arteritis, Takayasu arteritis and, rarely, infections such as syphilis.
• Previous aortic dissection or aortic surgery.
• Medicines: fluoroquinolone antibiotics have been linked to aneurysm and dissection; doctors avoid them when alternatives exist in people with aneurysms.
• Stimulants and heavy lifting: cocaine and amphetamines, and extreme straining, can trigger dissection in a weakened aorta.

Symptoms

Most thoracic aneurysms cause no symptoms and are found on an echocardiogram, chest CT or X-ray done for another reason. Large aneurysms can press on nearby structures:

• a deep ache in the chest or upper back
• hoarseness, from pressure on the nerve to the voice box
• cough, wheeze or breathlessness from pressure on the windpipe
• difficulty swallowing from pressure on the esophagus
• symptoms of a leaky aortic valve (breathlessness, fatigue) with root aneurysms

Sudden severe tearing pain is a sign of dissection or rupture and is an emergency. See aortic dissection.

How it is diagnosed and monitored

• Echocardiogram: measures the aortic root and ascending aorta and checks the aortic valve.
• CT angiography or MRI: gives precise measurements of the whole aorta; MRI avoids radiation for frequent follow-up.
• Measurements matter: the same method and points should be used at each scan, since a few millimeters can change decisions.
• Genetic testing and family screening: recommended for people with aneurysms at a young age, a family history, or features of a syndrome. First-degree relatives are offered aortic imaging.

Typical surveillance intervals

When surgery is recommended

Based on the 2022 ACC/AHA guideline, repair of the root or ascending aorta is generally recommended:

• at 5.5 cm or more in most people without a genetic condition
• at 5.0 cm or more when surgical risk is low at an experienced center, or with a bicuspid valve plus risk factors
• at 5.0 cm (sometimes 4.5 cm) in Marfan syndrome, and smaller thresholds in Loeys-Dietz syndrome, depending on the gene and family history
• when it grows 0.5 cm or more in one year, or 0.3 cm or more per year for two years in a row
• at 4.5 cm or more when heart surgery is being done for another reason, such as valve replacement
• whenever it causes symptoms

Descending thoracic aneurysms are usually repaired at 5.5 cm or more, or sooner with rapid growth or symptoms.

Treatment

Medical management

• Blood pressure control, often with beta-blockers or ARBs (losartan is commonly used in Marfan syndrome), aiming for a target set by your doctor, usually below 130/80 mmHg.
• Stop smoking, and treat cholesterol with statins when atherosclerosis is present.
• Exercise: moderate aerobic activity is encouraged; avoid heavy lifting, straining and isometric exercise such as maximal weightlifting. Ask your cardiologist for specific limits.
• Avoid stimulant drugs and, where possible, fluoroquinolone antibiotics.

Surgery

• Open surgical repair: the weakened section is replaced with a fabric graft. For root aneurysms, either a valve-sparing root replacement (keeping your own aortic valve) or a composite valve-graft (Bentall procedure) is used. Hospital stay is about a week; full recovery takes 2 to 3 months.
• Thoracic endovascular aortic repair (TEVAR): a stent graft is inserted through an artery in the groin and positioned inside the descending aorta. Recovery is quicker, but lifelong imaging is needed to check the graft.
• Hybrid procedures combine open and endovascular techniques for arch aneurysms.

Outlook

Small, stable aneurysms may never need surgery, and many grow slowly, by about 1 mm a year in the ascending aorta. Once an aneurysm reaches about 6 cm, the yearly risk of dissection or rupture rises sharply. Planned (elective) repair at experienced centers has low risk, typically a few percent or less for ascending aorta surgery, compared with very high mortality for emergency repair. This is why monitoring and timely surgery matter.

Frequently asked questions

What size thoracic aortic aneurysm needs surgery?

For most people, surgery is recommended when the ascending aorta reaches 5.5 cm, or 5.0 cm in selected low-risk patients or those with a bicuspid valve and risk factors. People with Marfan or Loeys-Dietz syndrome are often treated at smaller sizes. Rapid growth also triggers surgery.

What are the warning signs of a thoracic aortic aneurysm?

Most have no symptoms. Large aneurysms can cause chest or upper back ache, hoarseness, cough or difficulty swallowing. Sudden severe tearing pain in the chest or back is an emergency warning sign of dissection or rupture and needs a 911 call.

How fast does a thoracic aortic aneurysm grow?

Ascending aortic aneurysms typically grow about 1 mm per year, and descending ones a little faster. Growth is quicker in larger aneurysms and in genetic conditions. Regular scans with consistent measurements show your own growth rate.

Can I exercise with a thoracic aortic aneurysm?

Yes, in most cases. Moderate aerobic exercise such as walking, cycling and swimming is encouraged. Avoid heavy weightlifting, straining and holding your breath while lifting, which spike blood pressure. Your cardiologist can give limits based on your size and cause.

Is a thoracic aortic aneurysm hereditary?

It can be. About 1 in 5 people with a thoracic aneurysm has an affected relative, and conditions such as Marfan syndrome and Loeys-Dietz syndrome are inherited. Parents, siblings and children of affected people are usually advised to have aortic imaging and sometimes genetic testing.