Can echocardiography (echo) be used to monitor ascending aorta aneurysms?

Monitoring Ascending Aortic Aneurysms with Echocardiography

Echocardiography is useful for monitoring ascending aortic aneurysms, particularly for the aortic root and proximal ascending aorta, but should be complemented with CT or MRI for comprehensive assessment of the entire thoracic aorta.

Role of Echocardiography in Ascending Aortic Aneurysm Monitoring

Transthoracic Echocardiography (TTE)

• TTE is recommended as the first-line initial screening technique for evaluating thoracic aortic diseases 1
• Effective for visualizing and measuring:
  • Aortic root (excellent visualization)
  • Proximal ascending aorta (good visualization)
  • Mid-ascending aorta (requires dedicated views)
  • Aortic valve function (important in aneurysm assessment) 2

Accuracy and Feasibility

• TTE measurements correlate significantly with CT measurements with very small standard errors of estimate:
  • Annulus: r = 0.846
  • Sinuses of Valsalva: r = 0.967
  • Sinotubular junction: r = 0.965
  • Ascending aorta: r = 0.976 3
• TTE is particularly well-suited for serial follow-up of ascending aortic aneurysms, especially in patients with Marfan syndrome 2

Limitations of Echocardiography

• Limited visualization of:
  • Distal ascending aorta
  • Aortic arch
  • Descending thoracic aorta 2
• TTE is not recommended for surveillance of aneurysms in these locations 2
• May underestimate aortic dimensions compared to CT/MRI 1

Comprehensive Assessment Approach

Initial Evaluation

1. TTE is recommended at diagnosis to assess:

   • Aortic valve anatomy and function
   • Aortic root and ascending aorta diameters
   • Global aortic evaluation using all echocardiographic views 2

2. CT or MRI confirmation is required to:

   • Confirm TTE measurements
   • Rule out aortic asymmetry
   • Determine baseline diameters for follow-up
   • Visualize segments not well seen on TTE 2

Measurement Technique

• For TTE: Use leading-edge to leading-edge convention in end-diastole, perpendicular to the axis of blood flow 1
• For CT/MRI: Use inner-edge to inner-edge measurements 1
• ECG-gated images decrease motion artifact and improve edge depiction 2

Follow-up Protocol

Frequency of Monitoring

• Annual imaging is recommended for stable dimensions 2
• More frequent imaging (every 6 months) if:
  • Aortic diameter ≥4.5 cm
  • Shows significant growth from baseline
  • Approaching surgical threshold 2

Choice of Imaging Modality

• For aortic root and proximal ascending aorta only:

  • TTE may be sufficient for routine follow-up 2

• For comprehensive assessment:

  • CMR or CCT is recommended for surveillance of aneurysms at the distal ascending aorta, aortic arch, or descending thoracic aorta 2
  • Same imaging modality should be used for serial measurements to ensure consistency 1

Special Considerations

Genetic Syndromes

• For patients with Marfan syndrome or other genetic disorders:
  • Initial imaging at diagnosis and 6 months thereafter
  • Annual imaging if stability is documented 2

Transesophageal Echocardiography (TEE)

• More invasive but provides higher spatial resolution
• Useful when TTE images are suboptimal
• Can assess anatomic or geometric aortic valve area by planimetry 2
• Particularly useful before transcatheter aortic valve implantation (TAVI) 2

Pitfalls and Caveats

• Reverberation artifacts on echocardiography can mimic pathology 1
• Different measurement conventions between imaging modalities can lead to discrepancies 1
• TTE may overestimate transvalvular pressure gradient in the presence of a small ascending aorta (diameter <30 mm) 2
• Non-standard measurement approaches may lead to unreliable reporting and management conflicts 2

In conclusion, while echocardiography is valuable for monitoring ascending aortic aneurysms, particularly at the level of the aortic root and proximal ascending aorta, it should be complemented with CT or MRI for comprehensive assessment of the entire thoracic aorta, especially for distal segments not well visualized by TTE.