REVIEW

CURRENTOPINION Contemporary imaging of normal mitral valve

anatomy and function

0268-4705 � 2012 Wolters Kluwer

a b a

Philippe Debonnaire , Meindert Palmen , Nina Ajmone Marsan , andVictoria Delgadoa

Purpose of review

Mitral valve disease is highly prevalent. Accurate characterization of normal anatomy and function of themitral valve is crucial to understand the pathophysiology of mitral valve disease. This review summarizesrecent advances in noninvasive cardiac imaging to assess normal mitral valve anatomy and function andprovides an overview of the clinical applications of these novel imaging techniques in the evaluation ofpatients with mitral valve disease.

Recent findings

Echocardiography remains the first imaging technique for evaluation of the anatomy and function of themitral valve. However, advances in minimally invasive and transcatheter valve repair/replacementprocedures demand high spatial resolution images to accurately assess the anatomy of the mitral valve andits surrounding structures. Three-dimensional echocardiography improves two-dimensionalechocardiography morphological and functional mitral valve evaluation. Furthermore, computedtomography provides high spatial resolution three-dimensional data and may constitute the modality ofchoice for additional morphological or geometrical study of the mitral valve and surrounding structures. Inaddition, cardiac magnetic resonance permits accurate assessment of anatomy and function of the mitralvalve and is considered the method of reference to quantify mitral flow.

Summary

Any abnormality in any of the components of the mitral valve (annulus, leaflets, subvalvular apparatus, leftventricle and left atrium) may lead to mitral valve dysfunction. Current noninvasive cardiac imagingmodalities permit accurate assessment of mitral valve anatomy and function. These imaging techniquesrefine our diagnostic performance, provide additional (patho)physiological insights and help to design newstrategies for interventional or surgical treatment of the diseased mitral valve.

Keywords

anatomy, geometry, mitral valve, multimodality imaging

aDepartment of Cardiology and bDepartment of Cardiothoracic Surgery,Leiden University Medical Center, Leiden, the Netherlands

Correspondence to Victoria Delgado, MD, PhD, Department of Cardio-logy, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden,The Netherlands. Tel: +31 71 5262020; fax: +31 71 5266809; e-mail:v.delgado@lumc.nl

Curr Opin Cardiol 2012, 27:455–464

DOI:10.1097/HCO.0b013e328354d7b5

INTRODUCTION

Mitral valve disease is one of the most prevalentvalvular heart diseases. Despite the dramaticdecrease in rheumatic valve disease in industrializedcountries, the increased lifespan of the populationhas led to an increase in degenerative mitralvalve disease, fuelling the number of mitral valveinterventions [1,2]. Echocardiography is used as afirst-line imaging technique to study mitral valvedisease. However, more recently, advanced imagingtechniques such as three-dimensional echocardio-graphy, multidetector row computed tomography(MDCT) and cardiac magnetic resonance (CMR)were added to the diagnostic armamentarium tostudy the mitral valve [3,4]. These imaging tech-niques are sequentially applied to identify mitral

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valve dysfunction, to study the cause, morpho-logical lesions and mechanism of mitral valve dys-function (Carpentier triad), to assess hemodynamic,morphological and functional cardiac consequencesof mitral valve disease and to select, guide andevaluate the therapeutical approach [5

&

,6]. Toanswer all these questions, thorough knowledge

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KEY POINTS

� The normal mitral valve is a functional complex thatrelies on normal morphology, geometry and function ofall its constituents.

� Three-dimensional echocardiography improvesmorphological mitral valve evaluation and mitralannular structural and functional evaluation.

� MDCT allows in-depth study of mitral anatomy andCMR provides an alternative for quantitative mitralfunctional evaluation.

Imaging and echocardiography

of the normal morphological, geometrical andfunctional appearance of the mitral valve is crucial.Moreover, this knowledge is basic to design anddevelop novel treatment strategies for mitral valvedysfunction that aim at restoring normal mitralvalve anatomy and function.

This review focuses on the use and clinical valueof different imaging modalities to assess normalmitral valve anatomy and function.

IMAGING NORMAL MITRAL VALVE

The normalmitral valve is a functional complex thatconsists of mitral annulus, leaflets, subvalvularapparatus, left ventricle (LV), and left atrium (LA)[7,8]. Any abnormality in any of these componentsmay cause mitral valve dysfunction (stenosis/regurgitation). Structural mitral valve abnormalitiesare referred to as organic mitral valve disease.Functional mitral valve dysfunction is secondaryto LV remodeling with normal structural mitralvalve.

Mitral annulus

The mitral annulus consists of a discontinuousfibrous D-shaped ring between the LV and LA towhich the mitral valve leaflets are anchored [7,8].The anterior part of the mitral annulus is in closerelationship with the aortic annulus at the level ofthe left and noncoronary aortic valve cusps. Thispart is enforced by a fibrous continuity, so-calledaortomitral valvular continuity, which ends laterallyin the left and right fibrous trigones (Fig. 1, panel a)[7–9]. In contrast, the posterior part of the mitralannulus is more muscular and lacks a firm fibrouscord. Consequently, this site is prone to dilatationand calcification [8]. The three-dimensional shapeofthe mitral annulus resembles a saddle with peakslocated anteriorly and posteriorly and nadirs at theposteromedial and anterolateral commissures [10].This three-dimensional geometry optimizes stress

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distribution over the mitral leaflets [10]. Assessmentof mitral annular dimensions is important todetermine appropriate annuloplasty ring or mitralprosthesis size.

Noninvasive imaging modalities permit end-systolic quantification of the maximal antero-posterior diameter (minor axis) and the inter-commissural diameter (major axis) in appropriatereconstruction planes, characterizing the planarD-shaped morphology of the mitral annulus(Table 1) [5

&

,11]. Based on two-dimensional echo-cardiographic measurements, an anteroposteriorannular diameter more than 35mm measured atend-systole or an annular to end-diastolic anteriormitral leaflet length ratio more than 1.3 definesmitral annulus dilatation [12]. Three-dimensionalimaging modalities permit accurate alignment ofmultiplanar reformation planes through the mitralannulus and increase the accuracy of the measure-ments of the annular dimensions [11,13

&&

,14]. In aseries of 17 patients undergoing two-dimensionaltransthoracic echocardiography and MDCT, mitralannulus measurements performed on conventionaltwo-dimensional echocardiographic views overesti-mated the anteroposterior diameter by 23% andunderestimated the intercommissural diameterby 12% compared with MDCT. In contrast, echo-cardiographic measurements performed on correctanatomical views resulted in improved agreementwith MDCT measurements, with an underestima-tion of the anteroposterior diameter by 1% and anoverestimation of the intercommissural diameter by0.9% [11]. Subsequently, head-to-head comparisonbetween three-dimensional transesophageal echo-cardiography (TEE) and MDCT measurements ofmitral annular dimensions showed good agreementbetween both techniques [14]. These three-dimen-sional imaging techniques have refined the analysisof mitral annular geometry and have providedseveral parameters (annular height, minimal andmaximal width, height-to-commissural-width ratio,annular circumference, annular area and aortic-mitral annular angle) that may help to understandthe pathophysiology of mitral valve disease and todesign tailoredmitral valve repair techniques (Fig. 2)[13

&&

,15,16&

].In percutaneous mitral valve interventions,

the assessment of the anatomic relationship ofthe mitral annulus and its surrounding structuresis crucial, especially the coronary circumflex arteryand the coronary sinus withMDCT and CMR (Fig. 3)[17–20]. This is of major interest as the coronarysinus is a new target for percutaneous indirectannuloplasty devices that aim to reduce the antero-posterior diameter of the mitral annulus [5

&

].In patients with structurally normal hearts and in

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(a) RCC

NCCLCC

LAA

LAA

ALC

ALC

LETAMF

RFT

A1

A1

P1

P1

P2

P2

P3

P3

A2

A2

A3

A3

PMC

PMC

(b)

(c) (d)

FIGURE 1. Surgical view of the mitral valve. Panel (a) Schematic representation of mitral valve anatomy (with permission fromreference [9]). Panel (b) Surgical exposition of Barlow degenerated mitral valve. Panel (c) Three-dimensionalechocardiography of structurally normal mitral valve. Panel (d) Same patient as panel (c), now post mitral annuloplasty forfunctional mitral regurgitation. Note the morphologic resemblance of the valve on three-dimensional echocardiography andperoperatively. a, anterior mitral valve with scallops A1, A2 and A3; ALC, anterolateral commissure; AMF, aortic-mitralfibrosa; LAA, left atrial appendage; LCC, left coronary cusp of aortic valve; LFT, left fibrous trigone; NCC, non coronary cuspof aortic valve; P, posterior mitral valve leaflet with scallops P1, P2 and P3; PMC, posteromedial commissure; RCC, rightcoronary cusp of aortic valve; RFT, right fibrous trigone.

Imaging of normal mitral valve Debonnaire et al.

patients with heart failure and mitral regurgitation,MDCT and CMR showed that the coronary sinusis frequently located above the mitral annulus[18,19]. In addition, the circumflex coronary arterywas located between the coronary sinus and themitral annulus in 68%–80% of patients [18–20].These findings highlight the limited patients’eligibility for percutaneous indirect annuloplasty:the technique may be ineffective in reducing mitralregurgitation if the coronary sinus is not alignedwith the mitral annulus or may imply a high risk ofmyocardial ischemia if the coronary sinus coursesabove the circumflex artery [21]. Furthermore,MDCT provides the highest spatial resolution tocharacterize mitral annulus calcification, a potential

0268-4705 � 2012 Wolters Kluwer Health | Lippincott Williams & Wilk

limitation for coronary sinus-based annuloplastyprocedures.

In addition to the anatomical characterization,the function of the mitral annulus can be studied.The mitral annular area decreases approximately25% at mid systole due to atrial and ventricularmyocardial forces imposed upon the mitral annulusand its normal translational motion towards the LVapex [10]. Mitral-aortic valvular coupling can bestudied by evaluating changes of the aortic-mitralangle throughout the cardiac cycle [15]. These three-dimensional dynamic properties of the mitralannulus reduce mitral valve leaflet stress, enhancemitral leaflet coaptation and contribute to atrial andventricular performance by optimizing filling and

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Table 1. Geometric indices of clinical interest for thefunctional mitral valve complex

Annulus Anteroposterior diameter (minor axis)

Inter-commissural diameter (major axis)

Annular area and circumference

Annular width-to-height ratio

Aortic-mitral annular angle

Left atrium Left atrial diameter

Leaflets Coaptation depth

Coaptation length

Tenting area or volume

Posterior and anterior mitral leafletangle (A2-P2 level)

Posterior and anterior mitral leafletlength (A2-P2 level)

Subvalvularapparatus

Chordal length

Interpapillary muscle distance

Papillary muscle tethering length

Papillary muscle anterior andposterior angle

Left ventricle Sphericity index (length-to-width ratio)

Posterior le

Anterior lea

ALAL

AL

AL

AL

A

A

AA

A

PP

P

P

LALA

LVLV2-ch3-ch

En face view

(b)(a)

P

Saddle-shap

3D-m

3D-volume

P

P

P P

PM

PM

PM

AO

AO

AO

Annular height

Tenting volume

FIGURE 2. Real-time three-dimensional echocardiography to aslandmarks on three-dimensional reformation planes is performed,dimensional model of the mitral valve is generated by the softwarPanel (c) Several geometric indices of clinical interest can be meaatrium; LV, left ventricle; P, posterior; PM, posteromedial; 2-ch, twarrow, anteroposterior annular diameter (minor axis); yellow arro

Imaging and echocardiography

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ejection flow dynamics [7,10]. Assessment of mitralannular function may help to optimize surgicaltechniques and design devices for mitral valverepair.

Mitral leaflets

The mitral valve consists of the anterior andthe posterior leaflets that converge at the antero-lateral and posteromedial commissures (Fig. 1). Theanterior mitral leaflet is rounded and occupiesone-third of the annular circumference, whereasthe posterior mitral leaflet is elongated and narrowand is hinged to the remaining two-thirds of theannulus. Despite having comparable surface areas,this anatomic fact explains that the anterior mitralleaflet forms the greatest part of the atrial floor(Fig. 2). Based on the presence of two indentations,the posterior mitral leaflet is usually divided into alateral P1 scallop (close to the left atrial appendage),a bigger central P2 and a medial P3 scallop [22].The opposing segments of the anterior mitral leafletare similarly named A1, A2 and A3 scallop [7–9].Of note, indentations between the leaflets neverreach the mitral annulus in normal mitral valve [7].

Posterior leaflet angleaflet area

Anterior leaflet angleflet area

AL

AL

AL

AL

A

AA

A

A

A

A(c)

P

Ped annulus

odel

P

P PMPM

PM

PM

PM

PM

PM

AO

AOAO

AO

AO

AO

AO

Annular area

Annular diameters

sess mitral valve geometry. Panel (a) Indication of anatomicusing Mitral Valve Quantification software. Panel (b) A three-e. The saddle-like shape of mitral annulus is appreciated.sured. A, anterior; AL, anterolateral; Ao, aorta; LA, lefto-chamber; 3-ch, three-chamber; 3D, three-dimensional. Redw, intercommissural annular diameter (major axis).

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(a)

CS

CS CS

CS-GCV

LAD

CS-GCV

CS

LCX

LCX

LCX

LA LA

LA

LV LV

LV

MV

MVMVMV

Ao

Ao

AoRA

(b) (c)

(d)

FIGURE 3. Peri-annular anatomy by computed tomography (CT) and cardiac magnetic resonance (CMR). Panels a–c: CT,panel d: CMR. Panel (a) Volume-rendered reconstruction showing presence of coronary sinus in atrioventricular groove closeto the mitral annulus (upper panel). Short-axis view of mitral annulus showing close proximity of coronary sinus (lower panel).Anatomic eligibility for percutaneous indirect mitral annuloplasty is likely. Panel (b) coronary sinus courses superiorly of mitralannulus and left circumflex coronary artery (LCX) runs inferiorly of coronary sinus (upper panel). Short-axis view points out riskof LCX impingement in the case of percutaneous indirect mitral annuloplasty (lower panel). Panel (c) Mitral annularcalcification is seen on long-axis view of the left ventricle (arrows) and short-axis mitral annular view (detail). Panel (d) LCXpartly overlaps with coronary sinus at level of mitral annulus (with permission from reference [20]). Ao, aorta; CS-GCV,coronary sinus-great cardiac vein; LA, left atrium; LAD, left anterior descending coronary artery; LV, left ventricle; MV, mitralvalve; RA, right atrium.

Imaging of normal mitral valve Debonnaire et al.

The segmental anatomical identification is ofparamount importance when studying and report-ing on the morphology and function of the mitralvalve [6]. The location and extent of prolapsingsegments in organic mitral regurgitation or theexact localization of the restriction characteristicof functional mitral regurgitation (usually postero-medial segments) are essential for therapeuticmanagement strategies [5

&

,12]. Protocols for stand-ardized approach using two-dimensional and three-dimensional transthoracic or TEE, MDCT and CMRhave been reported [3,12,13

&&

,23,24]. Three-dimen-sional echocardiography provides the possibility ofsimultaneous three-dimensional display ‘en face’view of the mitral valve leaflets from the ventricularor atrial perspective (‘surgical view’) (Figs 1 and 4).This increases the accuracy of mitral valve evalu-ation by novice readers, improves the evaluation ofthe commissural regions and provides a commoncommunication platform between the cardiac sur-geon/interventionalist and cardiac imager [13

&&

,25].Two-dimensional TEE, three-dimensional TEE andMDCT provide the best spatial resolution to study

0268-4705 � 2012 Wolters Kluwer Health | Lippincott Williams & Wilk

mitral leaflet morphology and geometry [3].Attempts using CMR steady state free precession(cine) images are increasingly reported with reason-able results, but they suffer from suboptimal spatialresolution (Fig. 4) [26–28].

Normal leaflet length can be assessed in middiastole from the hinge point at the mitral annulustowards the leaflet tips. Its assessment can be usedfor indexation of geometric mitral valve measure-ments in functional mitral valve disease and caninfluence surgical management strategies in hyper-trophic cardiomyopathy patients with increasedLV outflow tract gradient and systolic anteriormovement of the anterior mitral leaflet, causingmitral regurgitation [29].

The parasternal and apical long-axis views ofthe LV allow quantification of themitral valve leafletgeometry (Table 1). At mid systole the coaptationdistance or height (4–6mmfrom coaptation point tomitral annulus plane) and the anterior and posteriorangles formed between themitral annulus plane andthe respective anterior and posterior mitral leafletscan be measured at the A1-P1, A2-P2 or A3-P3 level

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LALA

Ao

Ao

(a) (b)

(d) (e)

RV

LV

LVLA

LA

LAA

RA

(c)

LAA

LAA

LV

LV

FIGURE 4. Multimodality morphologic study of a patient with Barlow degenerated mitral valve leaflet. Panel (a) two-dimensional echocardiographic two-chamber view shows thickened leaflets and prolapse of anterior mitral valve leaflet(arrow). Panel (b) three-dimensional echocardiography surgical view illustrates complex Barlow degeneration with A2-A3scallop prolapse and flail A1 scallop (arrow). Panel (c) three-dimensional long-axis view indicates flail anterior leaflet. Panel(d) cardiac magnetic resonance (CMR) reveals prolapse of mitral valve on two-chamber view. Panel (e) CMR suggests A2prolapse on four-chamber view, although caution is warranted when diagnosing prolapse in this view becausemisinterpretation may occur due to the saddle-shaped mitral annulus. Ao, aorta; LA, left atrium; LAA, left atrial appendage; LV,left ventricle; RA, right atrium; RV, right ventricle.

Imaging and echocardiography

(Fig. 5) [3,12,30]. A triangular tenting area orvolume contained between the mitral annulusplane, the leaflet surfaces and the coaptation linecan be identified [12]. Increased tenting area andincreased posterior and distal anterior leaflet angleare important determinants of mitral regurgitationseverity and are related to adverse outcome aftermitral surgery for functional mitral regurgitation[12,31,32]. The coaptation length refers to the lengthbetween the tips of the leaflets and their coaptationpoint that is formed by the systolic overlap ofthe leaflets (6–10mm at A2-P2 level), providing acoaptation reserve, essential to maintain normalmitral valve function [3,7]. Its assessment shouldbe an integral part of the evaluation of per-operativesuccess of mitral repair. With the use of multiplanarreformation planes, three-dimensional echocardio-graphy and MDCT permit accurate assessment ofthese parameters (Fig. 5) [14].

Functionally, normal leaflet mobility through-out the cardiac cycle protects from systolic backflowof blood towards the left atrium, forms an essentialcomponent of the funnel-shaped LV outflow tractduring ejection and enables diastolic blood flow

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towards the LV without a significant forwardgradient [7]. A mitral valve area of 4–5 cm2 isconsidered normal [7,8]. The assessment of mitralleaflet mobility is pivotal to define the mechanismof mitral valve regurgitation according to the Car-pentier classification: normal, excessive (prolapse orflail) or restricted (rheumatic or functional mitralvalve disease) leaflet mobility [12].

Finally, spectral-Doppler and color-Dopplerechocardiographic methods can identify the pres-ence of regurgitation or stenosis and provide thecornerstone of quantitative functional mitral valveassessment (Table 2). Alternatively, mitral regurgi-tation can be detected as low signal intensity (signalvoid) on bright-blood steady state free precession-cine images and subsequently quantified by bloodflow imaging using velocity-encoded phase-contrastCMR [27]. Except for mitral valve planimetry,MDCT currently does not allow quantitative mitralvalve function assessment as it lacks blood flow dataand suffers low temporal resolution. Quantificationof mitral valve function by different imagingmodalities and applications will be extensivelydiscussed in other articles included in this issue.

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(a)

Aα3 Pα3

MVCht3

Aα2 Pα2

MVCht2

Aα1Pα1

MVCht1

(b) (c)

(d) (e) (f)

A3 A2 A1

ALC

P3

PMC

P2 P1

LV

LVLVLV

RA RAAo

LCX

LVOT

FIGURE 5. Segmental anatomy and geometric indices of mitral valve by computed tomography. Panel (a) Interpapillarymuscle distance on two-chamber plane. Panel (b) Short-axis view of mitral valve with A1-A2-A3 scallops, P1-P2-P3 scallops,anterolateral commissure (ALC) and posteromedial commissure (PMC). Panel (c) Short-axis view at level of mitral annulus tomeasure minor and major axis annular diameters (arrows). Panels (d, e, f) Reconstruction planes at A1-P1, A2-P2 and A3-P3level, respectively. The mitral valve coaptation height (MVCht), anterior angle (Aa) and posterior angle (Pa) can be quantified.Ao, aorta; LCX, left circumflex coronary artery; LV, left ventricle; LVOT, left ventricular outflow tract; RA, right atrium.

Imaging of normal mitral valve Debonnaire et al.

Subvalvular apparatus and left ventricleThe subvalvular apparatus consists of fibroustendinous chords and the papillary muscles. Theanterolateral papillary muscle usually arises fromthe apicolateral third of the LV and the postero-medial papillary muscle originates from the middlethird of the LV inferior wall, avoiding the inter-ventricular septum [7,8]. Both papillary musclesgive rise to several dozens of tendinous chords thatattach to the ipsilateral half of the anterior and

Table 2. Usefulness of multimodality imaging to study mit

Mitral valve 2D-echo

Anatomy

Annulus þþLeft atrium þþLeaflets þþþSubvalvular apparatus þþþLeft ventricle þþþ

Function

Mitral regurgitation þþþMitral stenosis þþþ

2D, two-dimensional; 3D, three-dimensional; CMR, cardiac magnetic resonance; ec

0268-4705 � 2012 Wolters Kluwer Health | Lippincott Williams & Wilk

posterior mitral leaflets. Commissural chords, how-ever, originate only from the papillary muscle inclosest proximity beneath [7,8]. Tendinous chordsremain at the same length throughout the cardiaccycle and give rise to several branches of chords thatcan attach to the edges of themitral leaflets (primarychords) or to the ventricular surface of the leafletbodies (secondary chords). Few tertiary chords canbe identified originating directly from the posteriorLV wall to the posterior mitral leaflet only [7,8].

ral valve anatomy and function

3D-echo MDCT CMR

þþþ þþ þþþþ þþ þþþþþ þ þ/�þ þþþ þ/�þþþ þþþ þþþ

þþ � þþþþþ þ/� þþ

ho, echocardiography; MDCT, multidetector computed tomography.

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Imaging and echocardiography

With two-dimensional transthoracic echocar-diography, the basal and mid short-axis as wellas long-axis bicommissural views of the LV allowsystematic morphological evaluation of the sub-valvular apparatus and end-diastolic measurementof the chordal length and various geometricalindices (Table 1) [8]. Chordal elongation can beencountered in fibro-elastic deficiency andMarfan’sdisease, for example [33]. The 908 (transgastric) two-chamber view on TEE provides a clear view ofthe subvalvular apparatus [13

&&

]. Furthermore,MDCT has demonstrated the highly variableanatomy of the subvalvular apparatus [3]. Althoughthe antero-lateral papillary muscle usually has oneor two heads and a single trabecularized insertionon the LV wall, the posteromedial papillary musclehas multiple anatomic variations with one tothree heads and multiple trabecularized ventricularinsertions [3].

The normal geometric relations of the mitralvalve leaflets described above depend on the geom-etry of the subvalvular apparatus. The interpapillarymuscle distance refers to the distance in between thebase or the heads of the papillary muscles in systolicshort-axis mid-ventricular view or in a LV longitudi-nal view, respectively (Fig. 5) [3,34]. This parameterreflects the displacement of the papillary musclesin patients with dilated left ventricles. Similarlyto the mitral leaflets, the anterior and posteriorangles and length between the tip of the papillarymuscles and the mitral annulus can be quantifiedas a measure of mitral leaflet tethering. Three-dimensional imaging techniques provide optimalassessment of all these geometrical indices. Acqui-sition of a full volume of the left ventricle with three-dimensional echocardiography and subsequentimage postprocessing displays best the entire sub-valvular apparatus from the LV perspective [13

&&

].Functionally, the subvalvular apparatus ensures

adequate leaflet mobility throughout the cardiaccycle by synchronous papillary muscle contractionin concert with ventricular contraction and rela-xation in normal hearts [7]. These forces are trans-mitted to the valvular leaflets by the primary chordsto ensure leaflet coaptation. Secondary chordaepermit limited bulging of the leaflet bodies, whichreduces leaflet stress in concert with the three-dimensional shape of the mitral annulus. Thesecondary ‘strut’ chordae only attach to the anteriormitral leaflet and are part of a ventriculovalvularfibrous loop, essential to suspend the aorto-mitralangle andmaintain normal LV shape, geometry andfunction [7]. Normal LV shape (sphericity index,end-diastolic volume index, end-systolic volumeindex) and systolic function [ejection fraction,(dys)synchrony] are major determinants of normal

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geometric relations and function of the subvalvularapparatus [3].

CLINICAL IMPLICATIONS

Studies of the normal mitral valve by differentnoninvasive cardiac imaging modalities have con-tributed to a wealth of (patho)physiological insightsand clinical applications in patients with mitralvalve dysfunction. Echocardiography remains thefirst-line imaging technique of choice for evaluationof mitral valve dysfunction (Table 2). Three-dimen-sional echocardiography provides additional infor-mation to study function and anatomy of the mitralannulus, quantify mitral valve dysfunction andevaluate mitral valve morphology, given by theease of segmental anatomy recognition. However,three-dimensional image quality depends on two-dimensional image quality, and still the temporaland spatial resolution are lower than two-dimen-sional echocardiography [13

&&

]. MDCT is highlysuited to study mitral valve anatomy (morphologyand geometry), given its optimal spatial resolution.Radiation exposure, use of iodinated contrast agents,limited temporal resolution and current lack ofapplications to quantify blood flow are current draw-backs to systematically applying MDCT for mitralvalve evaluation [35]. As MDCT-angiography isincreasingly performed to evaluate coronary arterydisease, the report should mention when abnormalmitral morphology or geometry is encountered.CMR is a valid alternative for quantitative functionalevaluation of the mitral valve in the case of sub-optimal acoustic window and contra-indication forTEE, but lacks spatial resolution to optimally addressmitral valve anatomy [28]. The costs, availability andhigh technical expertise needed for appropriateimaging additionally hamper the wide clinical useof CMR to image the mitral valve.

Current surgical and percutaneous techniquesor devices rely on careful noninvasive cardiacimaging for patient selection, planning, guidingand evaluation of the intervention. Morphologicmitral valve characteristics determine mitral valvereparability in organicmitral valve disease, whereasgeometric indices of the leaflets and subvalvularapparatus have been shown to determine severityof mitral valve dysfunction, reparability and out-come after repair in functional mitral regurgitation[12,31]. The importance of geometrical indicesin functional mitral valve disease enforced theidea of targeting therapeutically the subvalvularapparatus, resulting in different surgical possibi-lities such as LV remodeling techniques (Coapsyssystem, external balloon patch and so on), use ofneochordae and translocation or reconstruction of

Volume 27 � Number 5 � September 2012

Imaging of normal mitral valve Debonnaire et al.

papillarymuscles [10].MDCTmaybecomeuseful toevaluate the subvalvular apparatus prior to theabove-mentioned complex repair procedures [3].Moreover, there is a growing interest in percutane-ous techniques to treat mitral regurgitation.Devices for direct or indirect mitral annuloplasty(via coronary sinus approach), direct edge-to-edgeleaflet repair and percutaneousmitral valve replace-ment have been introduced into clinical practiceor are currently under development [5

&

]. MDCT aswell as CMR enables the study of the surroundinganatomy of the mitral annulus, which is of majorinterest in the selection of candidates for percuta-neous annuloplasty interventions via the coronarysinus, for example [4,5

&

,6].

CONCLUSION

The normal mitral valve is a functional complexthat relies on normal morphology, geometry andfunction of all its constituents. The role of three-dimensional imaging techniques to study the mitralvalve is increasingly recognized. Further develop-ment in this field of multimodality imaging willundoubtedly lead to novel (three-dimensional)applications and improved spatial and temporalresolution to study the (normal) mitral valve. Thisknowledge will ultimately refine our diagnosticperformance, provide additional (patho)physio-logical insights and help to design new strategiesfor interventional or surgical treatment of diseasedmitral valves.

Acknowledgements

The Department of Cardiology of Leiden UniversityMedical Center received research grants from Biotronik,Medtronic, Boston Scientific, St Jude Medical, and GEHealthcare. V.D. received consulting fees from St JudeMedical and Medtronic.

Conflicts of interest

There are no conflicts of interest.

REFERENCES AND RECOMMENDEDREADINGPapers of particular interest, published within the annual period of review, havebeen highlighted as:

& of special interest&& of outstanding interest Additional references related to this topic can also be found in the CurrentWorld Literature section in this issue (p. 556).

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2. Iung B, Baron G, Butchart EG, et al. A prospective survey of patients withvalvular heart disease in Europe: the Euro Heart survey on valvular heartdisease. Eur Heart J 2003; 24:1231–1243.

3. Delgado V, Tops LF, Schuijf JD, et al. Assessment of mitral valve anatomy andgeometry with multislice computed tomography. JACC Cardiovasc Imaging2009; 2:556–565.

0268-4705 � 2012 Wolters Kluwer Health | Lippincott Williams & Wilk

4. Van Mieghem NM, Piazza N, Anderson RH, et al. Anatomy of the mitral valvularcomplex and its implications for transcatheter interventions for mitralregurgitation. J Am Coll Cardiol 2010; 56:617–626.

5.&

Delgado V, Kapadia S, Marsan NA, et al. Multimodality imaging before,during, and after percutaneous mitral valve repair. Heart 2011; 97:1704–1714.

This article reviews the current status of transcatheter mitral valve pro-cedures and the crucial (peri)procedural role of different imaging techniques.6. O’Gara P, Sugeng L, Lang R, et al. The role of imaging in chronic

degenerative mitral regurgitation. JACC Cardiovasc Imaging 2008; 1:221–237.

7. Silbiger JJ, Bazaz R. Contemporary insights into the functional anatomy ofthe mitral valve. Am Heart J 2009; 158:887–895.

8. Ho SY. Anatomy of the mitral valve. Heart 2002; 88 (Suppl 4):iv5–iv10.9. Salcedo EE, Quaife RA, Seres T, Carroll JD. A framework for systematic

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Volume 27 � Number 5 � September 2012