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Aortic vestibule

The aortic vestibule is the smooth-walled portion of the left ventricular outflow tract (LVOT), located just below the aortic valve cusps. It extends from the anterior mitral leaflet to the aortic annulus, forming the transition zone between the left ventricle and the ascending aorta. Unlike the rough trabeculated myocardium of the ventricle, the aortic vestibule is smooth due to fibrous continuity with the mitral valve (the aortic–mitral curtain).

This region ensures laminar blood flow into the aorta during systole, minimizes turbulence, and supports proper functioning of the aortic valve apparatus. Pathological involvement of the aortic vestibule can occur in hypertrophic cardiomyopathy (HCM), aortic stenosis, infective endocarditis, and subaortic obstruction.

Synonyms

  • Left ventricular outflow tract (LVOT, muscular part)

  • Subaortic vestibule

  • Ventricular outflow portion

Function

  • Forms the outflow passage of the left ventricle into the ascending aorta

  • Maintains laminar blood flow into the aortic root during systole

  • Provides fibrous support to the aortic and anterior mitral valve leaflets

  • Plays a role in ventriculo-arterial coupling and systolic ejection

MRI Appearance

T1-weighted images:

  • Appears as a low-signal myocardium-lined chamber beneath the aortic valve cusps

  • Surrounded by hyperintense blood pool in LV and aorta

T2 Cine (Cardiac-gated balanced SSFP):

  • Demonstrates the aortic vestibule as a bright lumen with sharp myocardial borders

  • Cine sequences assess dynamic LVOT narrowing, systolic ejection, and valve motion

  • Abnormalities: LVOT obstruction in HCM, systolic anterior motion (SAM) of mitral leaflet, turbulence

STIR (Short Tau Inversion Recovery):

  • Suppresses fat to improve contrast between myocardium and blood pool

  • Highlights edema or inflammation near the outflow tract (e.g., myocarditis, post-surgical change)

T1 Post-Contrast (Gadolinium-enhanced MRI):

  • First-pass perfusion assesses blood flow into LVOT and aortic root

  • Late gadolinium enhancement (LGE) may show fibrosis at the septal-aortic junction, often in HCM

  • Enhances visualization of subaortic membrane or infiltrative pathology

MRI Non-Contrast Cardiac-Gated 3D Coronary Imaging:

  • High-resolution 3D whole-heart sequences display the aortic vestibule in continuity with the aortic valve and LV

  • Useful in patients who cannot receive contrast

  • Valuable for pre-surgical planning and congenital heart disease evaluation

CT Appearance

CT Coronary Angiography (CCTA):

  • Provides detailed 3D visualization of the aortic vestibule, aortic annulus, and LVOT

  • Clearly demonstrates the relationship with aortic cusps, coronary ostia, and mitral valve

  • Detects subaortic obstruction, calcification, vegetations, aneurysm, or prosthetic valve complications

  • Crucial in TAVR (transcatheter aortic valve replacement) planning for annular sizing and outflow tract assessment

CT image

Aortic vestibule anatomy CT axial image -img-00000-00000

MRI image

Aortic vestibule mri image