Aortic Stenosis: Echocardiographic Features and Diagnostic Insights

Aortic stenosis (AS) presents distinct echocardiographic characteristics that are crucial for accurate diagnosis and assessment. The primary imaging modalities used in evaluating AS include M-mode echocardiography, two-dimensional (2D) echocardiography, and color Doppler ultrasound. In some cases, advanced techniques such as tissue Doppler imaging may also be employed to further assess myocardial function and disease progression.

M-Mode Echocardiographic Findings

One of the earliest indicators of aortic stenosis can be observed using M-mode echocardiography. This technique allows for the assessment of aortic valve motion, particularly the separation between the right coronary cusp and the non-coronary cusp. In a normal heart, the aortic valve opens widely during systole, with an expected separation of 16–26 mm. In the presence of stenosis, this opening is significantly reduced, often measuring less than 15 mm, indicating restricted valve mobility due to structural changes.

Two-Dimensional Echocardiography Insights

2D echocardiography provides a more comprehensive and visual assessment of the aortic valve anatomy. By obtaining images in the optimal parasternal long-axis or apical view, clinicians can trace the valve orifice during systole to calculate the aortic valve area (AVA). A valve area of less than 2 cm² is generally indicative of significant aortic stenosis. Additionally, 2D imaging can reveal morphological changes such as increased echogenicity (brightness), thickening of the valve leaflets, and calcification. These structural alterations often lead to commissural fusion, further impairing valve function.

Color Doppler and Flow Assessment

Color Doppler ultrasound plays a vital role in evaluating the hemodynamic consequences of aortic stenosis. It typically reveals a high-velocity, systolic, jet-like flow across the stenotic valve. This flow pattern appears as a dense, unidirectional, and late-peaking spectral Doppler signal. A peak velocity exceeding 2 m/s is considered a key diagnostic criterion for aortic stenosis. As the severity increases, the time required to reach peak velocity (acceleration time) becomes prolonged, as does the total ejection time. These changes reflect the increased afterload the left ventricle must overcome to eject blood through the narrowed orifice.

Left Ventricular Adaptation and Hemodynamic Consequences

Chronic pressure overload caused by aortic stenosis leads to significant left ventricular (LV) remodeling. The LV compensates by increasing wall thickness—a condition known as concentric hypertrophy. While this adaptation initially helps maintain cardiac output, it eventually leads to increased myocardial oxygen demand and reduced compliance. Over time, this can result in symptoms such as dyspnea, angina, and syncope, signaling the need for more aggressive management, including possible valve replacement.