Transcript MORPHOLOGY OF THE MITRAL VALVE

MORPHOLOGY OF THE
MITRAL VALVE
M. Kuduvalli
ELEMENTS OF MITRAL VALVE
APPARATUS
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Annulus
Leaflets
Subvalvar apparatus
- Chordae tendinae
- Papillary muscles
MITRAL ANNULUS
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Zone of junction which serves as attachment to
the muscular fibres of the atrium, ventricle,
and attachment of the mitral valve
Attached to two fibrous trigones
-The right fibrous trigone which forms a dense
junction between the mitral, tricuspid and
aortic (non-coronary cusp) annuli, and the
membranous septum
-The left fibrous trigone which lies between the
aortic (left cusp) and the mitral annuli
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Between the two trigones, the mitral valve is in
continuity with the aortic wall and there is no
fibrous mitral annulus in this region
FIBROUS SKELETON OF THE HEART
SPATIAL RELATIONSHIP BETWEEN
MITRAL, AORTIC AND TRICUSPID VALVES
MITRAL ANNULUS
Mitral annulus is a dynamic structure
 Has a sphincter like function, effectively
decreasing the valve area by about a
quarter during systole
 This is secondary to contraction and
relaxation of the basoconstrictor muscles
(bulbospiral and sinospiral)
 Dilatation of the annulus occurs
posteriorly
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IMPORTANT STRUCTURES
SURROUNDING THE MITRAL
ANNULUS
MITRAL LEAFLETS
Form a continuous veil attached to the
circumference of the mitral annulus
 Free edge hangs into the LV, and is split
by indentations
 Two well defined and constant
indentations:
- Anterolateral commissure
- Posteromedial commissure
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MITAL LEAFLETS
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Commissural areas
(identified by
presence of
commissural
chordae) divide the
continuous mitral
veil into two leaflets:
- Anterior (aortic)
leaflet
- Posterior (mural)
leaflet
MITRAL LEAFLETS
Covered with endocardium
 Distinct ridge on atrial side which
- defines line of leaflet closure
- separates leaflets into two zones
- rough zone distal to the ridge
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(represents surface of coaptation)
- clear zone proximal to the ridge
ANTERIOR MITRAL LEAFLET
Semicircular or triangular
 Attached to around 3/8th of
circumference of the mitral annulus
 Has common attachment to the cardiac
skeleton with
- left coronary cusp
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of aortic valve
- half of non-coronary cusp
ANTERIOR MITRAL LEAFLET
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Rough zone receives the chordae
tendinae
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Forms boundary dividing the outflow
and inflow tracts of the left ventricle.
ANTERIOR MITRAL LEAFLET
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Direct continuity
between AML
and the aortic
wall
Gap between
aortic and mitral
valves is filled
with an intervalvular septum.
Fibrous mitral
annulus is absent
here
1.Intervalvular
septum
2. AML
3. PML
POSTERIOR MITRAL LEAFLET
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Quadrangular in shape
Attached to around 5/8th of the circumference
of the mitral annulus
Margin has two indentations, forming three
scallops:
- Anterolateral
- Middle
- Posteromedial
Cleft chordae insert into these indentations
MITRAL LEAFLETS
POSTERIOR MITRAL LEAFLET
Additional third zone, k/a basal zone,
which is between the clear zone and the
annulus. It receives insertion of the basal
chordae
 Basal zone is most obvious in the middle
scallop since the majority of basal
chordae insert here
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SUBVALVAR APPARATUS
PAPILLARY MUSCLES
Two groups of LV papillary muscles
- Anterolateral
- Posteromedial
 Each group supplies chordae to their
respective halves of both leaflets
 Arise from the anterior and posterior
walls of the left ventricle respectively
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SUBVALVAR APPARATUS
PAPILLARY MUSCLES
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May have one or more bellies each.
Anterolateral usually has one
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Tip points towards the respective
commissure
SUBVALVAR APPARATUS
PAPILLARY MUSCLES
Morphological type
Completely tethered
Free and finger like
Intermediate type
Adherent to myocardium 1/3rd or more protruding Considerable trabecular
Protrudes very little
freely into LV cavity
attachments and
into LV cavity
tethering
SUBVALVAR APPARATUS
CHORDAE TENDINAE
Fibrous strings that originate from tiny
nipples on the apical portion of the two
papillary muscles
 Majority have branching pattern, either
soon after their origin from the papillary
muscles, or just before their insertion into
the leaflets
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SUBVALVAR APPARATUS
CHORDAE TENDINAE
Chordae Tendinae
Commissural
chordae
Chordae of
Anterior leaflet
Main chordae
Paramedial
chordae
Chordae of
Posterior leaflet
Paracommissural Basal chordae
chordae
Rough zone
chordae
Cleft chordae
COMMISSURAL CHORDAE
Two in number, one for each commissure,
with similar names
 Arise as a main stem which branches
radially to insert into the free margins of
the commissural regions
 Their attachment defines the extent of the
commissural areas
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CHORDAE OF THE A.M.L
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Typically splits into 3
cords soon after its
origin from the
papillary muscles
MAIN CHORDAE OF THE A.M.L.
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Two in number, one from each papillary
muscle
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Inserted at 4-5 O’clock posteromedially
and 7-8 O’clock anterolaterally
OTHER CHORDAE OF THE A.M.L.
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Paramedial chordae
- Insert near the middle of the free edge
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Paracommissural chordae
- Insert between the main chordae and the
commissural chordae
CHORDAE OF THE A.M.L.
CHORDAE OF THE P.M.L.
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Basal chordae
- Unique to the PML
- Arise directly as single strands from the
left ventricular free wall or from the small
trabeculum carnae
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Rough zone chordae tendinae
- Similar to AML chordae, but shorter and
thinner
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Cleft chordae
- Insert into indentations on the PML
CHORDAE OF THE P.M.L.
BLOOD SUPPLY OF THE MITRAL
VALVE
Mitral leaflets and chordae are avascular
 Papillary muscle supply
- Anterolateral supplied by LAD and
in addition, by the Diagonal or an
OM from the Circumflex
- Posterolateral variably supplied by
branches of either the Lt. Circumflex
or the RCA
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TYPES OF MITRAL VALVE
PATHOLOGY
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Type I: Normal leaflet motion
- Annular dilatation
- Leaflet perforation
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Type II: Leaflet prolapse
- Chordal rupture
- Chordal elongation
- Papillary muscle rupture
- Papillary muscle elongation
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Type III: Restricted leaflet motion
- Restricted opening: Commissural fusion, leaflet and chordal
thickening
- Restricted closure: Excess tension on chordae during systole
TYPES OF MITRAL VALVE
PATHOLOGY
REFERENCE POINT
RHEUMATIC MITRALVALVE
MORPHOLOGY
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Can manifest as
- Stenosis
- Regurgitation
- Mixed
Three primary pathological processes
- Leaflet thickening
- Chordal thickening, shortening and
fusion
- Coaptation of the edges of the leaflets,
especially near the commissures
RHEUMATIC MITRALVALVE
MORPHOLOGY
Leaflet thickening can progress to:
- Calcification, first of leaflet, and
then peri-annular
- Retraction, leading to combined
stenosis and regurgitation
 Subvalvar apparatus involvment may
lead to different degrees of subvalvar
fusion
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ISCHEMIC MITRAL VALVE DISEASE
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Due to a combination of left ventricular wall
akinesia or dyskinesia and ischemia of the
papillary muscle itself, affecting the integrity of
the subvalvar apparatus
Papillary muscle necrosis can lead to rupture
either at its attachment at the base to the LV
wall or at its tip near the chordal attachments
Leaflets and chordae are avascular structures,
and are not directly involved in ischemic MR
MYXOMATOUS DEGENERATION
MORPHOLOGY
Chordal elongation and rupture
 Thickening of mitral leaflets
 Redundancy of mitral leaflets, billowing
into the left atrium in systole
 Degeneration and abnormal collagen
synthesis in the region close to the
chordal attachments
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INFECTIVE ENDOCARDITIS OF
MITRAL VALVE
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Leaflet involvement, with vegetation formation
and subsequent destruction of the leaflet
Thickening and healing around chronic leaflet
perforations
Annular and periannular abscesses,
subsequently involving the aortic valve
Chordal detachment due to destruction of
leaflet edges
Rupture of chordae and papillary muscles due
to their primary involvement
OTHER DISEASES INVOLVING
MITRAL VALVE
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Marfan’s and Ehler-Danlos syndromes
- Annular dilatation
- Chordal elongation
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Idiopathic calcification of the mitral
annulus
- particularly in the posterior area, with
calcification extending into the LA
- seen more frequently in elderly women
OTHER DISEASES INVOLVING
MITRAL VALVE
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HOCM – associated with MR
- Distortion of the AML from contact with
the hypertrophic IVS during systolic
anterior motion of the AML
- Dilatation of the LV and the annulus in
long standing HOCM
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