Mitral StenosisMitral Stenosis

Meghan YorkMeghan York

September 23, 2009September 23, 2009

Outline: Mitral StenosisOutline: Mitral Stenosis

I.I. Normal Mitral Valve Anatomy Normal Mitral Valve Anatomy

II.II. Etiology and Epidemiology Etiology and Epidemiology

III.III. Echocardiography Evaluation Echocardiography Evaluation

IV.IV. Physiologic Disturbances Physiologic Disturbances

V.V. Treatment Options Treatment Options

Mitral Valve AnatomyMitral Valve Anatomy

Posterior leaflet Posterior leaflet encircles majority encircles majority of annulusof annulus

Anterior leaflet is Anterior leaflet is longer across longer across diameter of valvediameter of valve

Mitral Valve Orifice AreaMitral Valve Orifice Area

Normal 4 – 6 cm2Normal 4 – 6 cm2

Mild Stenosis 1.6 – 2.5 cm2Mild Stenosis 1.6 – 2.5 cm2

Moderate Stenosis 1.0 – 1.5 cm2Moderate Stenosis 1.0 – 1.5 cm2

Severe Stenosis < 1.0 cm2Severe Stenosis < 1.0 cm2

EtiologyEtiology

Rheumatic Fever (majority of cases Rheumatic Fever (majority of cases of mitral stenosis)of mitral stenosis)

Calcific Mitral StenosisCalcific Mitral Stenosis CongenitalCongenital Endocarditis with large vegetation Endocarditis with large vegetation

causing obstructioncausing obstruction

Etiology (continued)Etiology (continued)

Anoretic drugsAnoretic drugs CarcinoidCarcinoid Systemic LupusSystemic Lupus Rhuematoid ArthritisRhuematoid Arthritis MucopolysaccharidosesMucopolysaccharidoses Whipple’s DiseaseWhipple’s Disease Amyloid depositionAmyloid deposition

http://www.med.cmu.ac.th/student/patho/Lertlakana/043.html

Epidemiology: Rheumatic Epidemiology: Rheumatic Mitral StenosisMitral Stenosis

Leading cause of congestive heart failure Leading cause of congestive heart failure in developing countriesin developing countries

Without surgical intervention, mitral Without surgical intervention, mitral stenosis results in 85% mortality 20 years stenosis results in 85% mortality 20 years after onset of symptomsafter onset of symptoms

2/3 of all cases are in women2/3 of all cases are in women Age of onset of symptoms usually age 20 – Age of onset of symptoms usually age 20 –

4040 50% of patients with symptomatic MS 50% of patients with symptomatic MS

have history of acute rheumatic fever 20 have history of acute rheumatic fever 20 yrs prioryrs prior

Echocardiographic Echocardiographic EvaluationEvaluation

A) Valve anatomy, mobility, calcification A) Valve anatomy, mobility, calcification B) Assessment of severity:B) Assessment of severity:

1)Mitral valve area1)Mitral valve area- continuity equation method and PISA- continuity equation method and PISA- planimetry- planimetry- pressure half time method- pressure half time method

2)Transmitral pressure gradient (Bernoulli)2)Transmitral pressure gradient (Bernoulli)3)Sequelae (pulmonary hypertension, left 3)Sequelae (pulmonary hypertension, left atrial dilation, left atrial thrombus)atrial dilation, left atrial thrombus)

Valve anatomy, mobility, Valve anatomy, mobility, calcificationcalcification

Rheumatic Mitral Rheumatic Mitral StenosisStenosis

Medial and lateral Medial and lateral commissural fusioncommissural fusion

Thickening of leaflet Thickening of leaflet tipstips

Hockey stick Hockey stick appearance of leafletsappearance of leaflets

Doming of leafletsDoming of leaflets ChordaeChordae

FibrosisFibrosis ShorteningShortening FusionFusion CalcificationCalcification

Hockey stick appearance of anterior leaflet

Doming of leaflets in diastole

Chordal involvement

Calcific Mitral StenosisCalcific Mitral Stenosis

Mitral Annular Mitral Annular Calcification occurs Calcification occurs at annulus adjacent at annulus adjacent to posterior leafletto posterior leaflet

Calcification Calcification extends from extends from annulus to base of annulus to base of leafletleaflet

Leaflet tips remain Leaflet tips remain thin and flexiblethin and flexible

Use of 3D Use of 3D EchocardiographyEchocardiography

Can be transthoracic or Can be transthoracic or transesophagealtransesophageal

Improves determination of Improves determination of involvement of chordal structuresinvolvement of chordal structures

Further characterizes fibrosis and Further characterizes fibrosis and calcification of leafletscalcification of leaflets

3D Echocardiography

Fish Mouth Appearance

M-ModeM-Mode

Increased echogenicity of leafletsIncreased echogenicity of leaflets Decreased excursion and reduced Decreased excursion and reduced

separation of anterior and posterior separation of anterior and posterior leafletsleaflets

Reduced diastolic E-F slope of mitral Reduced diastolic E-F slope of mitral closureclosure

Paradoxical anterior diastolic motion of Paradoxical anterior diastolic motion of posterior mitral leaflet (due to tethering posterior mitral leaflet (due to tethering of posterior leaflet to anterior leaflet in of posterior leaflet to anterior leaflet in rheumatic MS)rheumatic MS)

Increased Increased EPSSEPSS

NormalNormal Severe Severe

E Point Septal Separation

Reduced diastolic E – F slope of closure

Diastolic Anterior Motion of Posterior Diastolic Anterior Motion of Posterior LeafletLeaflet

Normal Mitral Stenosis

Assessment of SeverityAssessment of Severity

Mitral valve areaMitral valve area

1) Continuity 1) Continuity equationequation

2) PISA2) PISA

3) Planimetry3) Planimetry

4) Pressure half time4) Pressure half time

Transmitral Pressure Transmitral Pressure GradientGradient

1)Bernoulli’s equation1)Bernoulli’s equation

Continuity EquationContinuity Equation

Cross sectional area of the mitral valve Cross sectional area of the mitral valve multiplied by velocity time integral of mitral multiplied by velocity time integral of mitral stenosis jetstenosis jet

==Cross sectional area of LVOT(or PA) multiplied Cross sectional area of LVOT(or PA) multiplied

by velocity time integral of LVOT (or PA)by velocity time integral of LVOT (or PA)

Therefore: Therefore: CSA(mitral)= stroke volume/VTI(mitral)CSA(mitral)= stroke volume/VTI(mitral)

Proximal Isovelocity Surface Proximal Isovelocity Surface area: PISAarea: PISA

Used for calculating continuity equation in Used for calculating continuity equation in setting of mitral regurgitationsetting of mitral regurgitation

Blood flow increases as nears the stenotic Blood flow increases as nears the stenotic orificeorifice

Color doppler flow parameters are adjusted Color doppler flow parameters are adjusted to demonstrate well defined hemispherical to demonstrate well defined hemispherical aliasing surface are on the atrial side of the aliasing surface are on the atrial side of the mitral orificemitral orifice

Velocity equals Nyquist limitVelocity equals Nyquist limit

CSA(mitral)=2 CSA(mitral)=2 ππ r r2 2 x velocityx velocityaliasingaliasing/velocity/velocitypk pk

transmitraltransmitral

PlanimetryPlanimetry 2D short axis imaging of mitral valve during 2D short axis imaging of mitral valve during

diastole allows direct planimetry of valve areadiastole allows direct planimetry of valve area Mitral valve is a planar elliptical orifice that is Mitral valve is a planar elliptical orifice that is

constant in mid diastoleconstant in mid diastole Planimetry should be done at the narrowest Planimetry should be done at the narrowest

cross sectional area at the leaflet tipscross sectional area at the leaflet tips Consider starting at apex and slowly scanning Consider starting at apex and slowly scanning

up to find most distal point of leaflets (mitral up to find most distal point of leaflets (mitral valve shaped like a funnel during diastole)valve shaped like a funnel during diastole)

Accuracy of measurement has been validated Accuracy of measurement has been validated by comparison to post surgical specimensby comparison to post surgical specimens

Pressure Half TimePressure Half Time

Principle: rate of pressure decline across Principle: rate of pressure decline across stenotic orifice is determined by CSA of stenotic orifice is determined by CSA of the orificethe orifice

Influence of LA & LV compliance assumed Influence of LA & LV compliance assumed to be negligibleto be negligible

Obtain doppler images of mitral inflowObtain doppler images of mitral inflow Pressure half time = time from VPressure half time = time from Vmaxmax to to

VVmaxmax/√2 /√2 Mitral valve area = 220/ pressure half timeMitral valve area = 220/ pressure half time

220220 t½ t½

MVA = MVA =

Transmitral Pressure Transmitral Pressure GradientGradient

Peak Diastolic Pressure gradient = 4(orifice Peak Diastolic Pressure gradient = 4(orifice velocity)velocity)22

Mean Diastolic Pressure gradient =Mean Diastolic Pressure gradient =4 (v4 (v11

22 + v + v2222 + v + v33

22+ . . . v+ . . . vnn22)/ n)/ n

Where vWhere vxx is an instantaneous velocity is an instantaneous velocity

Mitral valve area of 1 cm2 typically requires transmitral gradient of 20 mmHg to maintain normal cardiac output at rest.However, severe mitral stenosis can present with a resting gradientranging from 5 – 30 mm Hg.

Obstruction of trans-mitral blood flowIncreased flow velocity

Increased pressure gradient across valve

Left atrial dilationPulmonary hypertension

Pulmonary EdemaRight sided heart failure

Decreased LV filling

Decreased stroke volume

Treatment of Mitral Treatment of Mitral StenosisStenosis

Treatment of congestive heart failureTreatment of congestive heart failure DiureticsDiuretics Beta blockersBeta blockers

Treatment and stroke prophylaxis if Treatment and stroke prophylaxis if atrial fibrillation presentatrial fibrillation present

Percutaneous transvenous mitral Percutaneous transvenous mitral valvuloplastyvalvuloplasty

Surgical open mitral commisurotomySurgical open mitral commisurotomy Mitral valve replacementMitral valve replacement

Patient Selection for Patient Selection for ValvuloplastyValvuloplasty

1)Severity of symptoms and 1)Severity of symptoms and physiologic changesphysiologic changes

- resting and stress echo- resting and stress echo

2)Risk of procedural complications2)Risk of procedural complications

-resting echo-resting echo

Wilkins Score: Assessment of Mitral Valve Morphology

Selection for Selection for ValvuloplastyValvuloplasty

Score < 8: probably valvuloplasty unless:Score < 8: probably valvuloplasty unless: > 2+ mitral regurgitation> 2+ mitral regurgitation previous surgical commissurotomyprevious surgical commissurotomy

Score 9-11: possible valvuloplasty if:Score 9-11: possible valvuloplasty if: No mitral regurgitationNo mitral regurgitation Age < 45Age < 45

Score 12-14: surgical commissurotomyScore 12-14: surgical commissurotomy May consider as palliative procedureMay consider as palliative procedure

Palacios et al. Circulation. 2002

Stasis of blood flow and thrombus formation

Thank you!Thank you!