8.2 Aortic-Valve Anatomy, Morphology, and Function

Think in three dimensions before naming the valve

CCI task C1 is to assess aortic-valve structure and function. The normal valve has right coronary, left coronary, and noncoronary cusps attached within the aortic root. The root complex includes the LV outflow tract, virtual basal annular plane, cusp hinge points, sinuses of Valsalva, coronary ostia, sinotubular junction, and proximal ascending aorta. A cusp opens into its sinus during systole and coapts with the other cusps in diastole. Valve morphology should therefore be described together with root and ascending-aortic anatomy, not as an isolated bright line.

Use an optimized parasternal long-axis view to show LVOT-to-aorta continuity, cusp excursion, coaptation, root, and proximal ascending aorta. This plane usually displays portions of the right and noncoronary cusps, but the exact intersection varies; it cannot prove cusp number by itself. In a zoomed parasternal short-axis view, angle until the leaflet tips and commissures are seen en face. Evaluate systolic opening, when separate cusps and commissures are most reliably distinguished. Freeze multiple frames, sweep above and below the cusp tips, and confirm the finding in long axis or another window.

Recognize common morphologic patterns

A tricuspid valve normally forms a triangular systolic opening. With degenerative calcific disease, cusp bases and bodies become thickened and bright, mobility decreases, and acoustic shadowing increases. Aortic sclerosis describes thickening or calcification without hemodynamically important obstruction; spectral Doppler is required to determine whether stenosis is present. Do not infer a gradient from calcification or call a mildly thickened valve stenotic without velocity data.

A bicuspid aortic valve has two functional cusps, often because two embryologic cusps are fused. A fibrous raphe may appear within the larger conjoint cusp, so the valve can look tricuspid in diastole and two-cusped in systole. Look for an elliptical or fish-mouth systolic opening, doming in long axis, eccentric closure, unequal cusp size, and the fusion pattern. Heavy calcification can conceal the raphe and simulate either bicuspid or tricuspid anatomy. When TTE cannot determine morphology, state that limitation and recommend no independent diagnosis; the interpreting clinician may integrate TEE, CT, or prior imaging.

Bicuspid disease is associated with enlargement of the root or ascending aorta and, in some patients, coarctation. Image and measure the aortic segments according to protocol, compare prior measurements made by the same convention, and inspect the suprasternal arch when indicated. A normal current gradient does not remove the aortopathy question. Less common unicuspid or quadricuspid valves require careful confirmation and often multimodality correlation; avoid forcing an unusual short-axis image into a familiar category.

Rheumatic aortic disease tends to involve commissural fusion and cusp-edge thickening, frequently with mitral disease. Congenital valvar stenosis may show doming. A subaortic membrane or dynamic LVOT obstruction can produce high velocity below a normally opening valve, while supravalvar narrowing occurs above it. Use color Doppler and PW mapping from the LV cavity through the LVOT and valve to localize acceleration before assigning obstruction to the cusps.

Link anatomy to function

Assess systolic opening and diastolic closure in real time. Color Doppler from parasternal and apical views identifies the location and direction of accelerated systolic flow and screens for regurgitation. A mosaic indicates a range of velocities and aliasing, not a stenosis grade. Complete spectral acquisition uses PW in the LVOT and CW through the valve from multiple windows. Morphology supports interpretation: restricted calcified cusps make fixed valvar obstruction plausible, whereas normal excursion plus a late-peaking subvalvar signal points elsewhere.

Look for additional findings that alter function or safety: mobile masses, suspected vegetation, cusp perforation, prolapse, flail tissue, fenestration, endocarditis complications, or an aortic-root abnormality. Do not label artifact as a mass from one plane. Confirm mobility and attachment in orthogonal views, adjust gain, and immediately communicate a potentially urgent finding through the laboratory pathway.

A complete morphology statement answers: how many cusps are demonstrated; whether a raphe or commissural fusion is present; which cusps are thickened, calcified, restricted, prolapsing, or poorly seen; whether coaptation is intact; where flow accelerates; and whether root or ascending-aortic disease accompanies it. If image quality prevents certainty, document indeterminate morphology rather than converting an assumption into anatomy.

Preserve diagnostic uncertainty and serial comparability

Morphology can appear different when frequency, harmonic imaging, gain, zoom, or short-axis level changes. For follow-up, reproduce the prior view while also obtaining today's best orthogonal anatomy; never reduce quality merely to mimic an old image. Compare the same aortic segment using the same edge and cardiac-phase convention. If a cusp is hidden by shadow, describe which feature is not visualized and save the sweep demonstrating the limitation. Three-dimensional TTE may add an en-face perspective, but low spatial or temporal resolution and dropout still require 2-D confirmation. Clear documentation of indeterminate cusp number is more useful than false certainty that later measurements cannot reconcile.