Clinical Anatomy 2009 Anatomia de la valvula mitral.pptx

1. HORIA MURESIAN*
University Hospital of Bucharest-Cardiovascular Surgery, Bucharest,
Romania
As a result of the numerous clinicaland surgical data accumulated so far, the
classical image of the mitral valve—a bicuspid valve, with two leaflets and two
papillary muscles—undergoes significant modifications. The valve, included into
the larger concept of the mitral valvular complex unveils numerous important
valences and characteristics, among which, some represent newer concepts, of
clinicaland surgical significance: the valvular complexis a subtle and finely-tuned
system of elements acting in a coordinated manner; the mitral valve is an active
valve and not a mere passive flap bordering the atrioventricular junction. Not
least, the mitralvalve contributes to the make up and functionof the left ventricu-
lar outflow tract. The anatomical and functional interdependence between the
mitral valve and the left ventricular myocardium is evident not only followingtheir
particularities of vascularization but also it is reflected in morbid states such as
ischemic cardiac disease and dilated cardiomyopathy. All the new concepts and
ideas, ask for a more profound study of the clinical anatomy of the mitral valve,
underscoring the importance of a pertinent dialogue between specialists and by
using a more appropriate and unitary terminology. Clin. Anat. 22:85–98,
2009. V
C 2008 Wiley-Liss, Inc.
Keywords: anatomy mitral valve; echocardiography; valvular plasty
coordinated manner. Age and the various disease
INTRODUCTION
The thorough knowledge of the anatomy of the mitral
valve is of utmost importance for diagnostic interrogation
and surgery. This review article presents the most recent
data and emerging ideas regarding this vast and significant
topic and under- lines the clinical and surgical applications. In
fact, the mitral valve does not represent solely a passive flap
guarding the left atrioventricular orifice, but a finely-tuned and
active set of elements acting in a
processes change or alter this disposition and ask for a more
elaborate medical thinking and for skilled and more complex
surgical maneuvers.
THE MITRAL VALVULARCOMPLEX
Subsequent to the numerous clinical and anatomi- cal data
accumulated so far, the mitral valve is best understood and
characterizedtogether with the ad-
Abbreviations used: Ao, aorta; AoL, aortic leaflet of the mitral valve
(anterior leaflet); Ao-M, aorto-mural diameter of the mi- tral annulus; A1–
A3, echographical portions of the aortic leaf- let; C-C, intercommissural
diameter of the mitral annulus; CS, coronary sinus; Cx, circumflex branch
of the left coronary ar- tery; D1, first diagonal branch; FO, fossa ovalis;
right fibrous trigone; SC, superior (anterolateral) commissure; S-L, septal-
to-lateral diameter of the mitral annulus; SPM, superior (anterolateral)
papillary muscle; SVC, superior vena cava; S1, firstanterior septal branch.

2. a
See text or a further characterizationof ‘‘the annulus.’’
jacent cardiac structures that collectively constitute the mitral
valvular complex (Table 1) (Perloff and Roberts, 1972; Ho,
2002).
The combined action of the structures comprising
the mitral valvular complexmust ensure and facilitate:
commissural areas. The anterior mitral leaflet occu- pies
roughly one third of the annular circumference and is wider
than the posterior leaflet, depicting a
trapezoidal or semicircular outline. Because of its
the properly-timed passage of blood from the left atrium
into the left ventricle,
the tight systolic closure of the left atrioventric- ular
orifice (preventing thus the backflow of blood from the
left ventricle into the atrium),
the accommodation of blood, eventually fol- lowed by
its rapid, efficient and forceful ejection through the left
ventricular outflow tract into the aortic root. The mitral
valve consequently has additional physiologic roles
different from the tricuspid valve, as part of it
contributes to the formation of the left ventricular outflow
tract (furthermore, the mitral-aortic curtain is also a
component of the aorticroot).
•
•
•
Such important functional roles depend on the
coordinated action of interrelated anatomical ele-
ments: the left atrium, the mitral valve leaflets, ‘‘the
annulus,’’ the chordae, the papillary muscles, and
the left ventricular wall. Each of the aforementioned
components is equally important, as alterations in
the structure and function of any of these elements
may cause hampered emptying of the left atrium,
mitral valvular incompetence, and/or alterations of
the left ventricular ejection. Accumulatingdata
suggest the fact that mitral valve closure does not
represent a passive process; instead, the model of
an active valve emerges (Williams and Jew, 2004).
The implementation and the use of a correctter-
minology are of utmost importance in describing the
normal anatomy of the mitral valve or for the diag-
nostic interrogation and therapeutic approach in
mitral valve disease. (Anderson and Wilcox,1995).
The component parts of the mitral valvular complex
must be also considered in an attitudinally appropri-
ate fashion with the heart oriented as ‘‘in situ’’
(Anderson and Frater, 2006).
Fig. 1. Mitral valve leaflets. The mitral valve in
closed position as seen from the left atrium. Advanced dissection
of an adult heart specimen with only the aor- tic root and mitral valve
left in place. Elements in attitu- dinally correct orientation. LFT
and RFT ¼ left and right fibrous trigones of the heart. Sinuses of
the aorta: NF ¼ nonfacing and 2L ¼ left (or sinus 2) - following
the Lei- den nomenclature (Sauer and Gittenberger-de Groot,
1997). LAD, the left anterior descending; Cx, the cir- cumflex
branches of the left coronary artery; IPM, infe- rior papillary
muscle; M1-M3; the scallops of the mural leaflet; A1-A3, the
corresponding echocardiographic portions of the aortic leaflet
Aorto-mitral curtain (‘‘mitral-aortic continuity’’)

3. material, rendering pliable the posterior segment of the mitral
valve allowing thus the sequential dilatation and reduction of
the valvular circumference (the sphincteric mechanism). The
mitral valvular leaflets close along a solitary zone of
apposition; the commissures are no more than the ends of this
zone of apposition (as the line of apposition does not extend to
reach the annulus) and together with the clefts in the mural
leaflet act as pleats providing a tight closure of the valve in
systole (Victorand Nayak, 1994).
On microscopic examination, the leaflets have a fi- brous
skeleton (the fibrosa), covered towards the atrial side by a layer
of myxomatous connective tis- sue (the spongiosa). The atrial
and ventricular endo- cardium are continued over the leaflet
surface; atrial myocardium may stick in between the
endocardium and the spongiosa, for varying depths, especially
in the middle scallop of the mural leaflet
The valve leaflets are nonhomogenous structures and show
a nonlinear anisotropic behavior (May- Newman and Yin,
1995). Both leaflets are less extensible in the circumferential
than in the radial direction. The mural leaflet shows greater
extensibil- ity in both directions, possibly due to the more abun-
dant chordal sustain.
The aortic leaflet has a reduced circumferential length but
is wider than the mural leaflet and usually has no clefts. The
conspicuous and less pliable rough zone marks the line of
leaflet coaptation. With advancing age, nodules are visible at
this level, marking better the area of overlap with the mural
leaflet. More peripherally, the clear zone of the aortic leaflet is
thinner and more malleable. On the ventric- ular aspect, this
corresponds to the gutter formed between the arching chordal
attachments, constitut- ing an important portion of the left
ventricularout- flow tract (Nayak and Victor,2006).
The mural leaflet is a partially divided structure with three
or more scallops and the corresponding clefts. In spite of
their different shape, both mitral
leaflets share similar areas (Roberts and Perloff,
1972; Ho, 2002). Besides a rough and a clear zone analogous
to the aortic leaflet, the mural leaflet
characteristically has a basal zone often reinforced by atrial
myocardium.
The commissures and the underlying papillary muscles are
traditionally labeled: anterolateral (in fact: superior, posterior,
parietal, and left) and post-
eromedial (in fact: inferior, anterior, septal, and right)
(Kanani and Anderson, 2003; Anderson and
Frater, 2006). The more appropriate terminology, which will be
A3. Consequent to the fact that papillary and chordal sustain is
distributed to corre- sponding parts of the mitral valve
leaflets—i.e., those portions that will coapt during valve
closure, six anatomic-functional scallops eventually result and
these can be systematized in pairs of scallops facing a cleft or
a commissure. This nomenclature enables a more precise
characterization of mitral valve leaflets, both in normal cases as
well as in dis- ease (Fig. 1). The various degrees of severity
and patterns of mitral valve prolapse can even be quanti- fied, on
a scale ranging from 1 of 6 scallops to 6 of 6 (1/6–6/6), reflecting
not only the severity of the dis- ease, but also allowing a more
precise localization and orientation during diagnostic
interrogation and surgery (Muresian et al., 2006). Other
authorities (Kumar et al., 1995) speculate about taking into
account the so-called commissural cusps, but this might add
further ambiguities and confusion and such details are not
absolutely necessary; following Carpentier’s original
terminology, a prolapse involv- ing the A1 and M1 implicitly
comprises a prolapse of the superior commissure too.
However, this simpli- fied scheme will not cover all the
variations encoun- tered (Victorand Nayak, 1994).
The Annulus
The annulus represents a concept rather than a well-defined
anatomical structure (McAlpine, 1975; Ho, 2002). It is
differently defined from the anatomi- cal, echocardiographical,
and respectively, the surgi- cal points of view. Following
different landmarks, the annulus appears either more planar
or saddle- shaped. Anatomically, at the level of the
atrioventric- ular junction, fibro-elastic tissue extends from the
left and right fibrous trigones posteriorly describing however
an incomplete ring, otherwise completed by myocardium
(Angelini et al., 1988). The annulus is deficient towards the
aorta, the mitral-aortic curtain extending between the two
trigones (McAlpine,
1975). The insertion of the left atrial myocardium at this level
may serve as useful landmark for the aortic
(‘‘anterior’’) portion of the annulus. Echographically, the

4. Fig. 2. Mitral annulus. A superior and basal view of the
fibrous skeleton of the heart. The mitral annulus includes an
important muscular portion in its posterior aspect. The tricuspid
annulus is almost completely mus- cular but it was left in place in
order to reveal the origi- nal position of the right atrioventricular
junction and the general orientation of the two atrioventricular
orifices. The aortic sinuses follow the same Leiden nomenclature
(cf. Fig. 1). The nonfacing sinus was scalloped, for a
better view. The origin of the two coronary arteries (LCA and
RCA) is well seen. The intercommissural diam- eter of the mitral
annulus is marked by the C-C double headed arrow. The so-
called septal-to-lateral diameter is actually the aorto-mural diameter
(Ao-M). Note that the literally-speaking and anatomically-positioned
sep- tal-to-lateral diameter (S-L) skirts closer to the inter-
commissural one.
No matter what definition of the annulus is cho- sen, the
orifice at the level of the left atrioventricular junction appears
ovoid or D-shaped (Fig. 2), with a longer intercommissural (I-
C) and a shorter septal- to-lateral axis (S-L). Literally, the
anatomical septal- to-lateral diameter stretches closer to the
intercom- missural one. It is hence more correct to define and
refer to the aorto-mural diameter, which joins the aortic (anterior)
annular midpoint with the mural an- nular midpoint (Ao-M).
Body-weight-corrected data pertaining to these dimensions are
as follows:0.39–
0.59 mm/kg for the intercommissural and 0.32–0.48 mm/kg for
the aorto-mural diameters, respectively
(Fyrenius et al., 2001). However, dimensions are underestimated
of utmost importance for the prevention of mitral
insufficiency (Timek et al., 2002a).
The annulus depicts complex modifications during the
cardiac cycle. The following clinical-echocardio-
graphical terminology is briefly presented. The wid- ening and
narrowing define the annular flexion (the sphincteric
mechanism). There is a 23–40% varia-
tion in the annular circumference between the sys- tolic and
diastolic configurations (van Rijk-Zwikker et al., 1994). The
excursion or annular descent is the
movement in the apical-to-basal direction. annulus
excursion toward the apex can be evaluated by
using the two-dimensional
Mitral
better
strain
imaging technique (Hayashi et al., 2006). Mitral an- nular

5. Fig. 3. Mitral valve in situ. a: Lateral view of a heart
specimen opened at the level of its left aspect. A part of the
mitral valve comprising the M2 scallop was removed. A portion of
the left atrial wall was also removed, to reveal the left aortic
sinus (2L) with the ori- gin and proximal tract of the left coronary
artery (LCA). The accompanying greater cardiac vein (GCV) is
also evident. After traveling around the annulus, the GCV becomes
the coronary sinus (CS). Note its relationship with the mitral
annulus. From the cavity of the left atrium the orifice of the
left atrial appendage (LAA) is visible, as well as two of the
pulmonary veins (*). Note also the false cords connecting the
two papillary muscles (SPM and IPM) between them and with
the
septum. The actual position of the papillary muscles is: superior,
parietal, left, posterior (for the traditionally called anterolateral
muscle) and inferior, septal, right, and anterior (for the
posteromedial). There is also a visible difference between the
whitish leaflet and the darker left atrial myocardium. b: A more
advanced dis- section of the same specimen. Same view and
coordi- nates as in Figure 3a. The atrial septum was removed
except the fossa ovalis (FO); under this, the coronay sinus (CS)
which was deliberately unroofed, travels towards its confluence
with the right atrium. A valve in the CS is also visible. Note the
intimate relationship between the various portions of the mitral valve
and the LCA, GCV, and CS.
The aortic (anterior) intertrigonal portion of the annulus
also depicts a dynamic behavior: studies have revealed
changes in response to modifications in hemodynamic loading
and ventricular contractility (Parishet al., 2004).
The aortic and mitral annular areas change in a reciprocal
fashion during late diastole and late sys-
tole (32% 6 8% for aortic annular area and 13% 6
13% for mitral annular area) but such dynamic changes
seem not to be mediatedthrough the ana-
tomic fibrous continuity (Timek et al., 2003a).
Proceeding counter clockwise from the left fibrous trigone
towards the atrial septum (Figs.3a and 3b),
the circumflexbranch and the greater cardiac vein
continued by the coronary sinus mark the external position of
the annulus—a detail of surgical rele- vance. The reverse
and annulus on one hand and the ventricular wall on the other.
Different from the tricuspid valve, there is no direct attachment
of the mitral valve to the ven- tricular septum, although the
papillary muscles are frequently connected to the septum or to
the right fi- brous trigone by false cords (Loukas et al., 2007).
The length and the reciprocal ratio between papillary muscles
and cords show individual variations, but some studies
demonstrated similar annular-to-papil- lary muscle tip distances
in the 2-, 4-, 8-, and 10- o’clock positions that also correlate with
mitral annu- lar diameter (Sakai et al., 1999) and which are rele-
vant for the proper choice of cordal length during reparative
surgery.
Mitral valvular leaflets, scallops, clefts, commis- sures, on
one hand, and tendinous cords on the other, are reciprocally
definable. The aortic leaflet, and each of the scallops of the
mural leaflet, have a convex free margin and receive cordal

6. Fig. 4. Definition of the components of the mitral valve. The
mitral valvular complex is exposed by cutting the heart specimen at
the level of the left aspect, through the M1 scallop of the ML.
In this specimen, the ML has four scallops (M1-M4). The inferior
papillary muscle (IPM) depicts more fascicles (heads); the supe- rior
papillary muscle (SPM) consists of two fascicles one of which lies
directly under the superior commissure (SC). Note that the
corresponding portions of the leaf- lets that will coapt in systole,
have a convexfree margin
and receive cordal support from different papillary mus- cle
fascicles. The clefts and commissural areas have a concave free
margin and receive cordal support from a directly underlying
muscular fascicle or head. The ap- proximate position of the
annulus is also evident. It is also of clinical significance to note
that the papillary muscles form an almost circumferential support
for the leaflets, except under the aortic leaflet of the mitral
valve, where the left ventricular inflow and outflow tracts
communicate.
immediately underneath, a cordal support that diverges
(dichotomously or in a fan-like manner) while approaching
the leaflet. Following their shape and cordal distribution, each
scallop of the mural leaflet can be considered as a ‘‘mini-
aorticleaflet.’’
The tendinous cords represent complex rope-like structures.
Their inner layer is composed of tightly bound collagen; the
outer layer consists of loose col- lagen and elastic fibers and
contains blood vessels. The tendinous cords are covered by a
layer of endo- thelial cells (endocardium). Fibroblasts are
evenly distributed through both the inner and outer layers. The
presence of blood vessels suggest an additional nutritional role
for the leaflets (Ritchie et al., 2005). The cords depict different
microstructures according to their type, with higher levels of
DNA and collagen at the level of the marginal cords of the
size and decreases with age (Lim and Boughner,
1976; Liao and Vesely, 2003).
The weakest portion, corresponding to their nar- rowest
section and where cords usually tear, is
located close to
(Sedransk et al.,
cords varies with
their insertion into the leaflet
2002). Tension in the tendinous cordal
type (greater in the strut
cords) and in line with left ventricular pressure, reaching a
maximum in or just prior to early systole (Lomholt et al., 2002).
The tendinous cords intermingle within the very substance
of the leaflet’s, contributing to their fi-
brous framework. The maximal cordal intermingling
occurs at the level of the leaflets rough zone. Some of the
cordal intraleaflet extensions reach the annu- lus and the two
fibrous trigones (Fig. 5b).

7. the AoL
Main stem of cleft cords of the ML
Third orderc
Basal cords of ML Basal posterior cord
Typeof cord Major role Equivalenttraditional terms
Proposed simplifiedclassification
Marginal cords Essential for coaptation ‘‘First order’’
Roughzone cords Essential for leaflet geometry ‘‘Second order’’
Strut (sustain) cords
Basal cords
Essential for ventriculargeometry
Annular reinforcement ‘‘Third order’’
AOL, aortic leaflet; ML, mural leaflet.
a
Inserting on the free edge of the leaflet.
b
Inserting on the ventricularaspect of the leaflet and contributingto the rough zone.
c
Originfrom the posterior left ventricular wall.
physiologic situations as well as in disease (Scam- pardonis et
al., 1973).
The picture resulting from the classical works is
that of the mitral valve, a bicuspid valve, with two leaflets and
two papillary muscles but this is far from what we perceive
nowadays. The muscular-cordal
arrangement of the subvalvular apparatus must
however ensure a circumferentially-constant support and with a
resultant even distribution of stresses over the leaflets. In the
mean time, the papillary-cor- dal disposition must not interfere
with the passage of blood from the atrium towards the ventricle
and from the ventricular inflow to the ventricular outflow com-
partment. The classical view of two papillary muscles
Fig. 5. The tendinous cords of the mitral valve. a: A special
anatomical preparation revealing the distribution of the cordal
support at the level of the two leaflets: aortic and mural. The
wider aortic leaflet allows to iden- tify better the marginal (free
adjacent commissural areas, to reveal the intra-leaflet disposition of
the cordal support. The tendinous cords proceed in the very
substance of the leaflet, contribut- ing to its fibrous framework.
Some branches of division reach the level of the annulus. An

8. Fig. 6. The vascularization of the papillary muscles. a: Left
view of a heart specimen in which the atrial walls were removed
except the junction between the superior vena cava (SVC) with the
right atrium. Large parts of the left ventricular walls were
removed in order to ex- hibit the papillary muscles. The ventricular
septum was also largely dissected, demonstrating the posterior
interventricular artery (doubled in this specimen and with origin
from the right coronary artery, RCA) and the first anterior septal
branch (S1). The close relationship between the Cx and the mitral
annulus is evident. The superior papillary muscle (SPM) and
adjacent left ven- tricular wall are vascualrized by an obtuse
marginal branch (OM), while the inferior papillary muscle (IPM),
is vascularized from the distal from the distal branches of the right
coronary artery (RCA). A conspicuous sinus node artery with origin
from the left coronary artery (LCA) travels posterior to the aortic
root, immediately superior to the mitral-aortic curtain (*) - a detail of
sur- gical relevance. b: A more advanced dissection reveal- ing the
vascularization of the papillary muscles, in a left dominant system.
The superior papillary muscle (SPM) is vascularized by a first
obtuse marginal branch (OM1) while the IPM is supplied by a
second marginal branch (OM2) and further by a retroventricular
branch. Note again the almost circumferentially-continuous papillary
structure.
should consequently be hence adapted: the two muscles
represent the ends of a more or less contin- uous column of
papillary structures that through a gap between them and under
the aortic leaflet, allow the passage of blood towards the left
ventricular out- flow tract.
The position of the papillary fascicles and their three-
dimensional orientation has an important role
in the distribution of forces and in assisting the proper
closure of the mitral valve (Scampardonis
et al., 1973; Jimenez et al., 2005; Chen and May- Newman,
2006). Papillary muscle displacement as occurring in
have origin in either or both coronary arteries. The superior
papillary muscle is vascularized by branches from diagonal,
circumflex, or even obtuse marginal branches of the left
coronary artery. The classical assertion regarding the
vascularization of the papil- lary muscles must be
reconsidered: the superior group that theoretically receives
multiple arterial branches can become infarcted even after
occlusion of a single diagonal branch (Kim et al., 2005). Fur-
thermore, the inferior group is seldom represented by a single
fascicle and the vascularization is pro- vided by more than one
arterial branch (H. Muresian,
2006, Personal communication). Arterial branches for the

9. aforementioned spaces. These two parameters must be
congruent though not identical.
coaptation is as equally impor- tant as coaptation between the
aortic and mural leaf- lets (Lai et al., 2002). Coaptation takes
place in a more apical plane ‘‘under’’ the level of the
annulus. The resultant coaptation triangle, tenting area, and
tenting volume, are all parameters of diagnostic and surgical
relevance (Watanabe et al., 2005). By join- ing their rough
zones, the valvular leaflets overlap for about 6–8 mm (Crooke
et al., 2007). The quanti- The Functional Reserve of the MitralValve
The mitral total leaflet area is 1.5–2 times the an- nular area.
Annular area values above 2.3 cm/m2
BSA are accepted as normal. The differencebetween
the total leaflet and the annular area is to be found in the
coaptation surface (i.e., the amount of leaflet
overlapping) and this characterizes the functional reserve of
the mitral valve, as this apparent leaflet excess makes possible a
tight coaptation under vari-
ous hemodynamic conditions (Muresian et al.,
2006). The ratio between the total leaflet area and annular area
is of surgical relevance as any imbal-
ance after the mitral repair may cause either poor coaptation or
systolic anterior motion of the aortic
leaflet The area of the aperture is roughly 2/3 of the annular
area. (Tsakiris, 1976). The valvular aperture between the valve
leaflets is ovoid in shape but
becomes crescent-shaped after ring annuloplasty or rheumatic
mitralstenosis.
The complex geometric distribution of the tendi-
nous cords inserting into the leaflets and the result- ant triangular
structures (Fig.8), act both under nor-
mal conditions, adapting the valve to the various he- modynamic
states and in disease, compensating for the papillary muscle
displacement and increased
tethering of the leaflets(He et al., 2000).
fication of the resultant also
diagnostic relevance, performed.
coaptation surface has
although not yet widely
The mechanisms of normal valve closure are com- plex and
still incompletely understood. The major processes are:
annular reduction (sphincteric mech- anism), followed by the
apposition of the mural leaf- let against the elevated aortic
leaflet (that functions as a trap door), reduction of all left
ventricular dimensions and the subsequent creation of a pres-
sure gradient between the ventricle and atrium that eventually
brings the leaflets toward the annular plane. Many interesting
details are emerging, such as the presence of a rich
innervation (Marron et al.,
1996) and contractile elements within the leaflets, the
contributionof left atrial myocardium to annular
dynamics (Glasson et al., 1997; Timeket al., 2002c,
2003b), the architecture of the left ventricular myo- cardium,
the spatial disposition of the left ventricular trabeculae and
papillary muscles (Loukas et al.,
2007), and the presence of receptors in the structure of the
leaflets.
The greater stress during valve closure is borne
by the narrower but better anchored mural leaflet. The aortic
leaflet shifts between the closed and respectively, the open
position offering a transitory support against which the mural
leaflet abuts. The commissural (and cleft) areas allow the
apposition and the concomitant reduction of the posterior leaflet
and annulus. The submacroscopic structure of the commissural
areas and the disposition of their fi- brous framework depict a
fan-like pattern which ena- bles the sequential widening and
narrowing of these particular areas of the valve. (Fig. 7).
Mitral valve plasty with excessive reduction and/or
immobiliza- tion of the mural leaflet abolishes this natural
pliabil- ity of the commissures causing scissoring stresses over
the commissural zones; this mechanism might be
responsible for the earlier failure of such techniques.
The anatomic aperture of the valve between the two
The Normal Asymmetry of the Mitral Valve
The mitral valve shows a natural asymmetry. The valve
leaflets do not depict a perfect bilateral sym- metry. The
scallops of the mural leaflet do not share even leaflet material.
The commissural areas are also asymmetric: the inferior
commissure has a lon- ger circumferential length and is
narrower. Papillary muscle and cordal support are not
symmetrically dis- tributed over the two imaginary halves of the
valve. (Fig. 9). It appears too simplistic (Kumar et al.,
1995) and of less and less clinicalsignificance, to divide the

12. Fig. 9. The normal asymmetry of the mitral valve. sought by the surgeon.b: A backlitmitral valve opened

13. and surgically corrected if considered into
the larger concept of mitral valvular complex. More- over, the
mitral valve must be considered not solely
as an atrioventricular valve, as it also contributes to the make-up
and functionof the left ventricular out- flow tract.
Newly-applied and versatile diagnostic principles and the
accumulating surgical experience have opened new horizons
and have offered new relevance
to the anatomy of this important and attractive region;
undoubtedly, the reciprocal influence between
clinical practice and anatomy will broaden these new frontiers,
for the benefit of our patients.
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