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Topic

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Left atrioventricular valve (mitral or bicuspid valve)

The mitral valve, also called the left atrioventricular valve or bicuspid valve, is located between the left atrium and left ventricle. It consists of two leaflets (anterior and posterior), supported by chordae tendineae that attach to the papillary muscles of the left ventricle. During diastole, the mitral valve opens, allowing blood to flow from the left atrium to the left ventricle; during systole, it closes to prevent backflow into the atrium. Its structural integrity is vital for maintaining unidirectional left heart flow and systemic circulation efficiency.

Synonyms

  • Left atrioventricular valve

  • Bicuspid valve

  • Mitral valve

Function

  • Opens in diastole to permit passive and active filling of the left ventricle

  • Closes in systole to prevent regurgitation of blood into the left atrium

  • Maintains unidirectional blood flow in the left heart

  • Works with papillary muscles and chordae tendineae to ensure valve stability and competence

MRI Appearance

T1-weighted images:

  • Leaflets appear as thin, hypointense structures at the left atrioventricular junction

  • Blood pool appears as signal void without contrast

  • Limited role for functional assessment

T2-weighted images:

  • Valve leaflets remain low signal intensity relative to myocardium

  • Turbulent flow or regurgitant jets may appear as signal voids within the atrium or ventricle

Cine MRI (SSFP / T2-weighted dynamic sequences):

  • Gold standard for functional assessment

  • Demonstrates leaflet motion in diastolic opening and systolic closure

  • Identifies stenosis, regurgitation, leaflet prolapse, restricted motion, or flail segments

  • Phase-contrast MRI quantifies flow velocity, stroke volume, regurgitant fraction, and orifice area

T1 Post-Contrast (Gadolinium-enhanced):

  • Enhances visualization of annulus, subvalvular apparatus, and surrounding myocardium

  • Cusps show little direct enhancement, but pathology (endocarditis, pannus, fibrosis) may enhance

  • Delayed enhancement sequences may show myocardial scarring from mitral regurgitation or stenosis

CT Appearance

Non-contrast CT:

  • Leaflets are thin and poorly visualized unless calcified

  • Mitral annular calcification appears as hyperdense curvilinear deposits

Contrast-enhanced CT (CT Angiography):

  • Clearly demonstrates leaflets, annulus, chordae tendineae, and papillary muscles

  • Detects mitral stenosis, regurgitation, prolapse, vegetations, prosthetic valve integrity

  • Multiplanar reconstructions are crucial for preoperative valve repair/replacement planning

MRI images

Mitral valve, Left atrioventricular valve, Bicuspid valve - Copy

CT image

Mitral valve, Left atrioventricular valve, Bicuspid valve ct AXIAL image -img-00000-00000