Ascending aortic aneurysm

Last revised by Mateusz Wilczek on 31 May 2022

Ascending aortic aneurysms are the most common subtype of thoracic aortic aneurysms and may be true or false aneurysms. 

Ascending aortic aneurysms represent 60% of thoracic aortic aneurysms

Typically ascending aortic aneurysms are an incidental finding and the patient is asymptomatic. Rarely, the patient may present with symptoms and signs of rupture (e.g. pain, hypotension). 

Ascending aortic aneurysms are defined as a permanent dilatation of the ascending aorta with a diameter ≥1.5 times the expected normal diameter or an ascending aortic diameter ≥4 cm in people <60 years 7.

True aneurysms can result from a wide variety of conditions:

False aneurysms are seen in the setting of trauma, particularly deceleration injuries, as well as potentially post-thoracic aortic surgery. 

Ascending aortic aneurysms may manifest as a widening of the aortic or mediastinal silhouettes. The ascending aorta usually does not form part of the right cardiomediastinal margin in the first five decades. If it does, suspect dilatation or aneurysm formation.

ECG-gating results in superior image quality and pulsation artifacts often result in over-estimation of the ascending aortic diameter 5. Pulsation artefact is very common in non-gated CT scans, seen in up to 92% 8.

The diameter of the ascending aorta should be measured at multiple levels, making follow-up scans more accurate for comparison 4,5:

MRI may be preferred over CT for long-term follow-up, especially in younger patients in view of minimizing radiation exposure. 

As with other aortic aneurysms, increasing size results in an increased risk of rupture with the risk of rupture of ~7% per year in patients with an aneurysm >6.0 cm 5.

Treatment is advocated in patients with an aneurysm >5.0 cm or 5.5 cm in diameter or increasing at >0.5 cm per year. Smaller ascending aortic dilatation (>4.5 cm) is accepted in patients undergoing aortic valve replacement 4

ADVERTISEMENT: Supporters see fewer/no ads

Cases and figures

  • Case 1: true aneurysm
    Drag here to reorder.
  • Case 2
    Drag here to reorder.
  • Case 3: ascending aortic aneurysm
    Drag here to reorder.
  • Case 4
    Drag here to reorder.
  • Case 5
    Drag here to reorder.
  • Case 6
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.