Mitral valve anatomy alan

1. ANATOMY OF MITRAL VALVE
BY DR NIKUNJ
(CTS RESIDENT STAR HOSPITAL)
(Coordinator:DR P.SATYENDRANATH PATHURI)
(25/6/18)

4. THE ATRIO-VALVULAR JUNCTION
• The junction between the atrium and the valvular tissue is usually well delineated
by the different colors of these structures: the atrium is slightly pink, and the
leaflets are yellowish.
• This junction defines the hinge where the motion of the leaflets is initiated.
• The hinge allows demar- cation of the annulus fibrosus, which is not visible from
an atrial view.

5. ANNULUS FIBROSUS
• actually a discontinuous band of connective tissue that exists only in some parts of the
attachment of the posterior leaflet.
• The annulus in actuality does not exist at the attachment of the anterior leaflet because the
leaflet tissue is continuous with the aorto- mitral curtain that extends from the aortic valve
annulus to the base of the anterior leaflet

6. • At each extremity of the base of the anterior leaflet, the atrio-valvular junction is
reinforced by two dense triangular fibrous structures: the anterolateral and
posteromedial fibrous trigones.

7. • The shape of the annulus varies throughout the cardiac cycle
• During diastole, the shape is grossly circular . During systole, the annulus has a kidney
shape

8. • Instead of having a planar configuration, the annulus has a three-dimensional saddle-
shape configuration. The two lowest points are located at the fibrous trigones and the
• two highest points are located at the midpoints of the anterior and posterior annuli.
• The plane of the mitral valve annulus makes a 120° angle with the plane of the aortic valve
annulus.

9. The 26% ± 3% reduction of the mitral valve orifice area during systole results from the
contraction of the base of the heart and the displacement of the aorto-mitral curtain towards
the center of the orifice.

10. THE LEAFLETS
• The mitral valve comprises two
leaflets—1)anterior
• 2)posterior
• separated by two commissures.
These leaflets are the opening and
closing structures of the valve
• Optimal closure implies a precise
fitting between the surface area
of the leaflets and the orifice area
of the mitral valve.
• Although the anterior and
posterior leaflets have a dif-
ferent size and shape , with the
anterior leaflet more extended
vertically and the posterior leaflet
more extended transversally, they
have a similar surface area.

11. • The basal insertion of the
anterior leaflet occupies approx-
imately one third of the
circumference of the mitral
valve
• The remaining two thirds of the
circumference attaches to the
posterior leaflet and the
commissural tissue.
• The anterior leaflet is primarily
related to the left ventricular
outflow tract via the aorto-
mitral curtain whereas the
posterior leaflet is related to the
muscular parietal base of the
left ventricle. As a result of this
configuration, the maximum
stress during systole is concen-
trated at the midline of the
posterior leaflet

12. ANTERIOR LEAFLET
• ANTERIOR LEAFLET, also called the aortic leaflet, has a trapezoidal shape. Its base,
which measures 32 ± 1.3 mm, is inserted on the aorto-mitral curtain and the
adjacent fibrous trigones. The free edge presents with a slightly convex curvature.
At the midline, the height of the anterior leaflet averages 23 mm.
• From the base to the margin, two zones are clearly appa ent.
• 1)The proximal zone, called the atrial zone, is regular, thin, and translucent.
• 2)The distal zone, called the zone of coaptation or rough zone, is irregular and
thicker because of the numerous chordae attached to its ventricular side. The two
zones have a similar surface area.
• The surface of coaptation, which has a height of 7 to 9 mm,
• During diastole, the anterior leaflet divides the left ventricle into two functional
areas, the inflow chamber and the outflow tract.

13. • The surface of coaptation, which has a height of 7 to 9 mm

14. POSTERIOR LEAFLET
• The posterior leaflet is inserted approximately
on two thirds of the annulus, to the crest of
the ventricular wall. The free edge is deeply
scalloped by two indentations ,separating
three segments: the anterior, middle, and
posterior scallops are also called P1, P2, and
P3, respectively, to facilitate valve analysis. By
convention, the corresponding areas of the
anterior leaflet are called A1, A2, and A3, and
the commissures AC and PC.
• The size of the scallops of the posterior leaflet
differs. The largest is the middle scallop (P2)
and the smallest is the anterior scallop (P1)
• the posterior leaflet presents two zones from
its base to the free margin: the atrial zone is
smooth and translucent and the coaptation
zone is thicker

15. • THE COMMISSURES may be described
as a functional entity consisting of two
different structures: the commissural
leaflet, which provides continuity
between the anterior and posterior
leaflets, and the coaptation surfaces
with adjacent anterior and posterior
leaflets.
• The commissural leaflet is a small,
triangular segment of leaflet tissue. Its
base is attached to the annulus and its
free edge is supported by one or two
characteristic fanlike chordae.
• As a result of this configuration, the
junction between the anterior and
posterior leaflets does not reach the
annulus but forms a Y-shaped line of
coaptation.

17. THE SUSPENSION SYSTEM
• The leaflets are connected to the
ventricular cavity by a suspension system
called the subvalvular apparatus. The
suspension system has two functions:
• one is to facilitate he opening of the
leaflets during diastole (active opening);
• the other is to prevent the upward
displace- ment of the leaflets above the
plane of the annulus during systole.
• To accomplish these two functions, the
suspension system consists of two
structures with different charcteristics:
• THE PAPILLARY MUSCLES with contractile
properties and
• THE CHORDAE TENDINEAE with elastic
properties.

18. THE PAPILLARY MUSCLES
• insert on the ventricular wall, are usually
organized into two groups, designated
posteromedial and anterolateral, positioned
below the corresponding commissures
I—Large and bulky with a single head generating
numerous chordae.
II—Large and bulky with multiple heads
attaching numerous chordae.
III—Narrow and having few chordae.
IV—Arch shape from which arise several
chordae; the arch may form an arcade with
several trabeculations attached to the
myocardium.
V—Adherent to the ventricular wall and
generating multiple chordae
.

19. • The anterior papillary muscle most
often has a type I configuration
with occasionally an adjacent type
III papillary muscle attaching the
commissural chordae.
• The posterior papillary muscle
usually has a type II configuration
with one head attaching the
chordae of the anterior leaflet, one
head attaching the commissural
chordae, and one head attaching
chordae of the posterior leaflet.

20. • The papillary muscles are implanted on the muscular wall of
the left ventricle at a junction situated approximately 1/3
from the apex and 2/3 from the annulus
• The distance between the tip of the papillary muscle and the
plane of the mitral valve orifice also varies, with an average
of 22 ± 5 mm

21. THE CHORDAE TENDINEAE
THE CHORDAE TENDINEAE extend from the papillary
muscles to the leaflets . Three types can be described
depending upon their attachment on the leaflets
BASAL (OR TERTIARY) CHORDAE extend from the
papillary muscle or directly from the ventricular wall.
The basal chordae are attached to the base of the
posterior and commissural leaflets or to the annulus.
INTERMEDIARY (OR SECONDARY) CHORDAE extend
from the papillary muscles. The intermediary chordae
are attached to the ventricular side of the leaflets.
MARGINAL (OR PRIMARY) CHORDAE are attached to
the margin of the leaflets. The space between two
marginal chordae does not exceed 3 mm and their
attachment to the leaflet is often bifurcated or
trifurcated

24. FOUR ANATOMICAL STRUCTURES CLOSE TO THE ANNULUS ARE AT RISK
DURING SURGERY
• The circumflex artery runs
between the base of the left
atrial appendage and the
anterior commissure, 3 to 4 mm
from the leaflet attachment,
and then moves away from the
rest of the posterior annulus.
• The coronary sinus skirts the
attachment of the pos- terior
leaflet. It is initially in a lateral
position, and then crosses the
artery and becomes medial,
closerTo the posterior leaflet
attachment but 5 mm superior
to the annulus.
• The bundle of His is located
near the posteromedial trigone.

25. FOUR ANATOMICAL STRUCTURES CLOSE TO THE ANNULUS ARE AT RISK
DURING SURGERY
• The noncoronary and left
coronary aortic cusps are in
close relationship with the base
of the anterior leaflet
• .the nadir of these cusps is 6 to
10 mm away from the anterior
mitral valve annulus, a distance
that repre- sents a safety zone
for the placement of sutures in
this area provided that the
needle is properly oriented
towards the ventricle.

26. THANK YOU