Mitral valve

Anatomy

The mitral valve consists of two leaflets, the anterior (A) and the posterior valve leaflet (P), which together have a surface area of 4-6cm. At the inner edges of the leaflets chordae tendinae are attached, which ensure that the leaflets did not prolapse back into the atria during systole. The chordae attach to two large papillary muscles, that are part of the muscular tissue of the left ventricle.

Cross section of the heart valves

The mitral valve can be visualized in many views: PLAX, PSAXmv, AP4Ch, AP5Ch, AP2Ch, AP3Ch and subcostaal4Ch. A prolapse of the MV is best assessed on PLAX. However, mitral regurgitation should be assessed in all views. In case of major abnormalities of the mitral valve 3D TEE has additional value in assessing the anatomy and function.

Scallop partition of mitral valve

Regurgitation

Quantification of mitral valve regurgitation

Grading severity mitral regurgitation
MR severity classes 𝜁MildModerateModerateSevere
Grade 1 or 1+Grade 2 or 2+Grade 3 or 3+Grade 4 or 4+
Qualitative
Valve morphologyNone or mild leaflet abnormalityModerate leaflet abnormalityModerate leaflet abnormalityFlail leaflet / large coaptation defect
or minimal tentingor moderate tentingor moderate tentingor severe tenting
Colour flow MR jetSmall, centralIntermediateIntermediateVery large central jet or eccentric jet adhering,
swirling and reaching the posterior wall of the LA
Usually <4cm² Usually 4-6cm² Usually 6-8cm² Usually >8cm²
<20% of LA20-30% of LA30-40% of LA>50% of LA
Flow convergence zone 𝛼No or small faintDenseDenseLarge throughout systole, dense, holosystolic
CW signal of MR jetParabolicPartial or parabolicParabolic or triangularTriangular
Semi quantitative
Vena contracta width (mm)<33 to <55 to <7≥7 (>8 for biplane) 𝛽
Pulmonary vein flowSystolic dominanceVariableSystolic bluntingSystolic pulmonary vein flow reversal 𝛾
MV inflowA wave dominant 𝛽VariableE-wave dominant (E>1.2m/s) 𝜀E-wave dominant (E>1.2m/s) 𝜀
VTI mitral / VTI LVOT<1Intermediate>1.2 𝜀 >1.4 𝜀
Quantative
EROA (mm²)<2020-2930-39≥40
R Vol (mL)<3030-4445-59≥60
RF (%)<3030-3940-49≥50
Structural parameters
LV and LA size Usually normalNormal or dilatedUsually dilatedUsually dilated
PA pressure Usually normalNormal or elevatedNormal or elevatedUsually elevated
CW, continuous wave; EROA, effective regurgitant orifice area; LA, left atrium; LV left ventricle; MR, mitral regurgitation; PA pulmonary artery; RF, regurgitant fraction; R Vol regurgitant volume; VC, vena contracta.
𝛼 At Nyquist limit of 50-60 cm/s.
𝛽 For average between AP4Ch an AP2Ch.
𝛾 Unless other reasons, of systolic blunting (atrial fibrillation, elevated LA pressure).
𝛿 Usually after 50 years of age.
𝜀 In the absence of other causes of elevated LA pressure and of mitral stenosis.
𝜁 Different thresholds are used in secondary mitral regurgitation where an EROA >20mm² and regurgitant volume > 30mL identify a subset of patients at increased risk of cardiac events.

Echocardiographic criteria for the definition of severe mitral valve regurgitation: an integrative approuch

ParameterCriteria
Qualitative
Valve morphologyFlail leaflet/ruptured pappilairy muscle/large coaptation defect
Colour flow regurgitant jetVery large central jet or eccentric jet adhering, swirling and reaching the posterior wall of the LA
CW signal of regurgitant jetDense/triangular
OtherLarge flow convergence zone *
Semiquantitative
Vena contracta width (mm)≥7 (>8 for biplane) **
Upstream vein flowSystolic pulmonary vein flow reversal
InflowE-wave dominant ≥1.5 m/s ***
OtherTVI mitral/TVI aortic >1.4
QuantativePrimarySecundary ****
EROA (mm²)≥40≥20
Regugitant volume (mL/beat)≥60≥30
Enlargement of cardiac chamber/vesselsLV, LA
* At Nyquist limit of 50-60 cm/s.
** For average between AP4Ch an AP2Ch.
*** In the absence of other causes of elevated LA pressure and of mitral stenosis.
**** Different thresholds are used in secondary mitral regurgitation where an EROA >20mm² and regurgitant volume > 30mL identify a subset of patients at increased risk of cardiac events.

Severe MR because of prolaps

Causes of mitral valve regurgitation

Annulus dilationDegeneracyAcquired valve deviationSecundary
AtriumfibrillationMalcaptation in mitral valve stenosisBillowingRhythm disorders (LBBB-->diastolic MR)
LV dilationProlapsSAM in HCM
LA dilationFloppy valve
Flail leaflet
Chordal rupture
Ruptured Papillary muscle

Ruptured mitral chordae tendineae assessed with 3D TEE

Stenosis

Quantification of mitral stenosis

ParameterMildModerateSevere
MVA (cm²)> 1.51.5 - 1.0< 1.0
PGmean (mmHg)< 55 - 10> 10
PHT (m/s)< 9090 - 150> 150

Causes of mitral stenosis

AcquiredTumorCongenital
DegeneracyMyxomaParachute valve
Rheumatic feverCor triatriatum sinistrum

References

European Heart Journal - Cardiovascular Imaging (2022) 23, e171–e232
J Am Soc Echocardiogr. 2009 Jan;22(1):1-23; quiz 101-2
Eur J Echocardiogr. 2010 May;11(4):307-32
European Heart Journal (2017) 00, 1-53