16.3 Aortic Root, Aneurysm, Dissection, and Coarctation

Measure an aortic map, not one generic root

CCI task D8 includes the aortic root, aneurysm, dissection, and coarctation. In a nonforeshortened parasternal long-axis view, name the annulus, sinuses of Valsalva, sinotubular junction (STJ), and proximal tubular ascending aorta separately. Use zoomed 2-D imaging and measure perpendicular to the vessel's long axis; do not use an oblique line merely because it produces the largest number. Explore modified high parasternal windows when the ascending aorta extends beyond the routine image.

Do not substitute M-mode for the 2-D aortic measurements. An asymmetric root may require more than one plane, and CT or CMR can define the true maximum. Index or interpret diameters with the appropriate age, sex, body size, valve phenotype, and heritable-disease context rather than one universal adult cutoff. For serial comparisons, preserve the exact segment, cardiac phase, edge convention, plane, and modality. CT and MR commonly use different phases and wall-edge methods; review source images before calling growth.

Sweep the suprasternal probe from the ascending segment through the transverse arch, branch origins, isthmus, and proximal descending aorta instead of relying on one frozen arch image. Color helps orient flow but can manufacture linear boundaries from aliasing or poor scale. Save labeled cine loops with ECG, measure only a clearly identified segment, and state which portions are not seen. The abdominal aorta is a downstream hemodynamic checkpoint, not a substitute for imaging the thoracic lesion itself.

Describe aneurysm morphology and associated disease

When dilation is present, state its segment, maximum valid diameter, extent, and fusiform or saccular morphology. Examine aortic-valve cusp number, stenosis or regurgitation, root symmetry, LV size/function, and the visible arch and descending aorta. Bicuspid valve, coarctation, hypertension, atherosclerosis, inflammatory disease, and heritable aortopathy alter risk and surveillance. Look for mural thrombus, ulcer-like outpouching, periaortic fluid, or rapid interval change, but avoid assigning etiology from diameter alone. A poorly seen distal ascending aorta is a limitation, not evidence that it is normal.

Test a flap, then escalate suspected dissection

An intimal flap separating true and false lumens is the central echo finding of dissection. Seek independent motion, extension across more than one view, and color flow on both sides or through a communication. Classify the visible involvement: Stanford type A includes the ascending aorta; type B begins distal to the left subclavian artery without ascending involvement. Evaluate immediately for acute AR and its mechanism, root/ascending dilation, coronary or branch compromise when visible, LV dysfunction, pericardial effusion, and tamponade physiology.

Reverberation in the ascending aorta commonly mimics a flap. Repeat the finding in an orthogonal plane, move the transducer, and alter depth, focal zone, gain, and color scale. An artifact often remains at a fixed distance from a strong reflector, crosses anatomic boundaries, or moves in parallel with the aortic wall; a true flap follows aortic anatomy and moves independently. These tests reduce false positives but must not delay care. TTE cannot visualize every thoracic segment, and a negative study does not exclude acute aortic syndrome. New severe chest or back pain, pulse or neurologic deficit, acute AR, pericardial blood, or a convincing flap requires immediate communication and definitive CTA or, according to stability and protocol, urgent TEE or CMR. Report echo observations and complications rather than declaring safety from an incomplete window.

Combine anatomic and flow evidence for coarctation

Coarctation most often narrows the isthmus just distal to the left subclavian artery. From the suprasternal notch, record arch branching, transverse arch size, the narrowest diameter and length, relation to the left subclavian, poststenotic dilation, and collateral vessels. Sweep color through the transverse arch and proximal descending aorta. Use PW proximal to and through the suspected level to localize acceleration, then align CW with the highest jet. Significant obstruction often produces systolic acceleration with persistent forward flow into diastole rather than a purely systolic envelope.

Sample the abdominal aorta from a subcostal view. A delayed, blunted systolic upstroke with continuous antegrade diastolic flow supports important upstream obstruction. Examine for commonly associated bicuspid aortic valve, ascending-aortic dilation, LV hypertrophy/function, and other congenital lesions. Compare upper- and lower-extremity blood pressures and pulses through the clinical team.

Do not let 4V² become the entire diagnosis. Collaterals can lower the measured jet despite severe narrowing; a long segment, tortuous arch, poor alignment, high proximal velocity, low output, or repaired anatomy can make the simplified gradient misleading. In repaired coarctation, inspect for recurrent narrowing, aneurysm or pseudoaneurysm, but recognize that TTE may miss the repair site. CT or CMR defines the arch, lesion length, collaterals, branch vessels, and repair complications. The report should preserve segment and Doppler sample locations, waveform timing, associated findings, prior-study method, and reasons for urgent or cross-sectional escalation.