Can an ascending aortic aneurysm be seen on an echocardiogram (echo)?

Can Ascending Aortic Aneurysm Be Seen on Echo?

Yes, ascending aortic aneurysms can be characterized and visualized by transthoracic echocardiography (TTE), making it an appropriate first-line imaging modality for the aortic root and proximal ascending aorta. 1

TTE Capabilities for Ascending Aortic Aneurysm Detection

TTE effectively visualizes and measures the aortic root and proximal ascending aorta using parasternal long-axis and modified apical five-chamber views, with measurements taken from leading edge to leading edge at end-diastole. 1 The technique demonstrates excellent correlation with CT measurements (r = 0.976, SEE 0.41 mm) for the ascending aorta in patients with known aneurysms. 2

Specific Anatomic Segments Visualized by TTE

• Aortic root and sinuses of Valsalva: Optimally visualized in parasternal long-axis view with high accuracy (r = 0.967 correlation with CT). 1, 2
• Proximal ascending aorta: Well-characterized using left and right parasternal windows, particularly useful for annuloaortic ectasia and localized atherosclerotic aneurysms. 1
• Aortic arch: Visualized via suprasternal view, though with more limited accuracy (r = 0.87 correlation with CT) and only achievable in approximately 91% of patients (40/44 in validation studies). 2

Critical Limitations and Blind Spots

The distal ascending aorta and proximal arch represent a significant "blind spot" for TTE due to interposition of the trachea and left mainstem bronchus between the transducer and aorta. 1, 3 This limitation means that as much as 42% of the ascending aorta length may not be visualized by TTE, even with biplane imaging. 4

Technical Factors Affecting Accuracy

• TTE consistently underestimates maximum aortic diameter by 1-2 mm compared to CT/MRI due to the leading-to-leading edge measurement convention. 5, 3
• Image quality is compromised in patients with abnormal chest wall configuration, narrow intercostal spaces, obesity, pulmonary emphysema, or mechanical ventilation. 1
• Complete thoracic aorta visualization is achieved in only 80-85% of patients using combined TTE windows (parasternal, suprasternal, supraclavicular, subcostal). 1

When TEE Provides Superior Assessment

Transesophageal echocardiography (TEE) substantially improves diagnostic accuracy for thoracic aortic pathology, with sensitivity approaching 98-100% for aortic dissection and comprehensive visualization of most thoracic aortic segments. 1 However, TEE shares the same blind spot as TTE in the distal ascending aorta and proximal arch due to tracheal interposition. 1

Clinical Algorithm for Ascending Aortic Aneurysm Evaluation

Order TTE as the initial screening test to assess aortic root, proximal ascending aorta dimensions, and associated cardiac pathology (aortic valve morphology, aortic regurgitation, left ventricular hypertrophy). 1, 3

Recognize that TTE provides incomplete assessment of the entire ascending aorta, particularly the distal segment and arch, and may underestimate true dimensions. 3, 4

Obtain confirmatory CT angiography (CTA) with ECG-gating for comprehensive evaluation when: 1, 3

• TTE shows aortic diameter ≥4.5 cm
• TTE demonstrates growth ≥3 mm per year
• Surgical planning is being considered
• Complete anatomic assessment of the entire thoracic aorta is required

Use the same imaging modality with consistent measurement technique for serial monitoring to avoid false-positive growth assessments due to inter-modality measurement differences. 1, 5

Common Pitfalls to Avoid

Do not assume TTE overestimates aortic size—the evidence demonstrates TTE consistently underestimates dimensions compared to CT/MRI. 5, 3 This is clinically significant because relying solely on TTE measurements near surgical thresholds (5.0-5.5 cm) may delay appropriate intervention. 5

Do not rely on TTE alone for surgical decision-making in patients with borderline measurements, as the blind spot in the distal ascending aorta may miss the maximal diameter location. 3, 4

Ensure the suprasternal view is included in every TTE examination when evaluating for thoracic aortic disease, as this view is essential for arch assessment but is sometimes omitted in routine studies. 1, 3

Distinguish true dissection flaps from reverberation artifacts by confirming the flap moves independently of the aortic wall on M-mode and that color flow respects the flap boundaries. 1, 6