Aortic vestibule

The aortic vestibule is the fibrous, smooth-walled region of the left ventricle immediately beneath the aortic orifice. It forms the ventricular portion of the aortic root and is bounded superiorly by the aortic valve annulus and inferiorly by the muscular interventricular septum and anterior mitral leaflet. Embryologically, the aortic vestibule is derived from the ventro-superior cushion of the atrioventricular canal, not from the conal myocardium, which instead contributes to the right ventricular outflow tract.

The vestibule is characterized by its fibrous continuity with the anterior mitral leaflet and its lack of trabeculations.

Aortic vestibule vs left ventricular outflow tract (LVOT)

The aortic vestibule and the left ventricular outflow tract (LVOT) are closely related but not synonymous.

Aortic vestibule

• The aortic vestibule is the anatomical space immediately below the aortic valve.

• It is a smooth-walled, funnel-like portion of the left ventricle that channels blood toward the aortic orifice.

• Embryologically, it derives from the bulbus cordis (conus arteriosus equivalent on the left side).

• It is defined narrowly: the portion of the left ventricle just beneath the aortic valve leaflets.

Left ventricular outflow tract (LVOT)

• The LVOT is a broader functional and imaging-based term.

• It refers to the entire passage from the left ventricular cavity leading up to the aortic valve.

• Its boundaries include:

  • Inferiorly: the basal interventricular septum (just beneath the membranous septum).

  • Anteriorly: the anterior leaflet of the mitral valve.

  • Superiorly: the aortic valve annulus.

• Clinically, the LVOT is what echocardiographers measure (e.g., LVOT diameter, velocity-time integral) to calculate stroke volume and aortic valve area.