Etiology

  • MS is rheumatic in 99% cases.
  • Rheumatic heart disease-
    • Mitral – 65%
    • Aortic- 35%
    • Tricuspid- 6%
    • Pulmonary- rare
  • RHD is multivalvular in 38% cases.
  • Rheumatic mitral valve disease-
    • MS- 25%
    • MS + MR- 40%
  • Aschoff nodules are present in myocardium.
  • Fish mouth or button hole appearance
  • Correlation between pathology and type of mitral valve disease
    • Commissural fusion with fish mouth appearance in diastole and closure during systole- MS
    • Fixed orifice- MS + MR
    • Chordal contraction without commissural fusion- MR without significant MS
  • Causes of progression of rheumatic heart disease-
    • Recurrent rheumatic fever
    • Continuing autoimmune damage
    • Trauma due to blood turbulence causes damage
  • Etiologies of MS-
    • Rheumatic
    • Congenital
    • Rheumatoid
    • SLE
    • Malignant carcinoid
    • Amyloidosis
    • Methysergide
    • Hurler-Hunter
    • Fabry disease
    • Whipple disease
    • Mitral annular calcification
    • Infective endocarditis (large vegetations causing obstruction)
  • Conditions mimicking MS-
    • LA myxoma
    • Ball valve thrombus
    • Cor triatriatum

Pathophysiology

  • Normal MVA is 4 to 6 cm2
  • Tachycardia decreases diastolic LV filling time leading to increase in LA pressure.
  • Hyperkinetic circulatory states increase flow rate across mitral valve leading to increased transmitral gradient leading to increased LA pressure. Note that gradient is proportional to square of flow rate.
  • LV in MS-
    • LVEDV is reduced in 15% while it is normal in the rest
    • Failure of LVEDV and hence SV to increase with exercise
    • LV systolic function (LVEF etc) is reduced in 25% due to chronically reduced preload and increased afterload. It is normal in the rest.
    • RWMA of posterobasal segment due to extension of mitral valve scarring
    • LV diastolic dysfunction due to leftward shift of IVS
  • At MVA of 1 cm2, 20 mmHg gradient is needed for mitral flow.
  • Types of PAH in MS-
    • Passive
    • Reactive (due to PVH)
    • Obliterative
  • Reactive PAH is said to be present when PA mean pressure – LA mean pressure is more than 10 mmHg.
  • Effects of PAH in MS-
    • Right heart failure
    • Reduced cardiac output
    • Protection from pulmonary edema
  • RV failure occurs at RVSP of 70 mmHg.
  • Exercise hemodynamics in MS-
    • Moderate MS- spectrum-
      • One end- rise in cardiac output with rise in gradient- dyspnoea
      • Other end- inadequate rise in cardiac output with minimal rise in gradient- weakness
    • Severe MS-
      • Inadequate rise in cardiac output with rise in gradient- weakness with dyspnoea
  • LA in MS-
    • Causes of LA disease-
      • Increased pressure
      • Rheumatic inflammation of LA wall
    • LA pathology-
      • Dilation
      • Fibrosis
      • Disorganization of muscle
      • Calcification
      • Thrombus
    • Effects of AF on LA-
      • Further LA enlargement
      • Atrial muscle atrophy
      • Inhomogeneity of atrial conduction and refractoriness.
      • Propensity to persistent AF
  • Mitral stenosis grades (valve area in cm2)-
    • Very mild- 2.5 to 2.1
    • Mild – 2 to 1.6
    • Moderate- 1 to 1.5
    • Severe- less than 1
  • Smallest MVA compatible with life is 0.3 cm2.

Symptoms

  • Symptoms of MS-
    • Dyspnoea on exertion
    • Fatigue on exertion
    • Hemoptysis
    • Chest pain (15%)
    • Palpitations
    • Systemic embolism
    • Syncope
    • Hoarseness of voice
    • Right heart failure
  • Causes of syncope in MS-
    • Ball valve thrombus
    • PAH
    • Arrhythmias
  • Mitral facies is caused by dilated veins in cheeks.
  • Causes of dyspnoea in MS-
    • PVH
    • Reduced pulmonary compliance leading to increased work of breathing
    • Reduced vital capacity- due to interstitial edema and engorged pulmonary vessels
  • Features of dyspnoea in MS-
    • Dyspnoea on exertion
    • Orthopnoea
    • PND
  • Causes of hemoptysis in MS-
    • Rupture of bronchial veins or of pulmonary vein-bronchial vein collaterals
    • Rupture of pulmonary capillaries during pulmonary edema
    • Pulmonary infarction
  • Causes of chest pain in MS-
    • RVH
    • CAD
    • Coronary embolism
    • Idiopathic
  • Causes of hoarseness in AF (Ortner syndrome)
    • LA dilation
    • PA dilation
    • Enlarged tracheobronchial lymph nodes

Physical examination

  • Physical examination features of MS-
    • Features of right heart failure may be present (elevated JVP, edema, hepatomegaly, ascites)
    • Mitral facies- pink patches on cheeks
    • Pulse may be low volume
    • Pulse is irregular if in AF
    • JVP shows prominent a wave if PAH
    • JVP shows absent a wave if in AF
    • JVP is elevated if in right heart failure
    • Tapping S1 at apex if AML is pliable
    • Diastolic thrill at apex
    • Left parasternal heave if PAH
    • Palpable P2 if PAH
    • Loud S1 with prolonged Q-S1 interval
    • Loud P2 and narrow split of S2 if PAH
    • Absent LVS3 and LVS4
    • RVS4 if PAH and RVS3 if RV failure
    • OS
    • PES if PAH
    • MDM at apex
    • TR PSM and PR EDM (GSM) if PAH
  • Causes of soft S1 in MS-
    • Severe calcification of leaflets
    • Severe thickening of leaflets
  • In severe MS, Q-S1 is lesser compared to in mild MS due to higher left atrial v wave.
  • Cause of OS- sudden tensing of leaflets on completion of opening excursion
  • Causes of loud S1 in MS are-
    • Mitral valve closes at higher rate of rise of pressure in LV due to delayed mitral closure due to high LA pressure
    • Wide closing excursion of mitral valve
  • A2-OS interval- 40 to 120 msec
  • Causes of narrow A2-OS interval (< 80 ms)
    • Severe MS
    • Tachycardia
  • Causes of wide A2-OS interval (>100ms)-
    • Mild MS
    • Bradycardia
    • Slow fall of LV diastolic pressure- LV systolic or diastolic dysfunction
    • Low LA pressure- large compliant LA
  • Differentiation of A2-OS from A2-P2-
    • On standing, A2-P2 narrows while A2-OS narrows
    • On inspiration, triple sound occurs as A2-P2 and A2-OS both widen
    • OS occurs after P2
    • OS is loudest at apex while P2 is loudest at pulmonary area
  • P2 may occur after OS if there is RBBB
  • Absent OS means that the body of the leaflets is calcified (not tip alone)
  • Cause of increased A2-OS interval on standing- decreased venous return leading to LA underfilling leading to lower LA pressure leading to delayed mitral opening
  • Cause of decreased A2-OS interval during exercise- increased LA pressure leading to earlier mitral opening
  • Well’s index-
    • Q-S1 interval minus A2-OS interval
    • Expressed in units of 0.01 seconds
    • More than 2 units indicates MVA less than 1.2 cm2
  • MDM-
    • Low pitched
    • Rumbling
    • Intensity is not related to severity
    • Duration is related to severity- in mild MS there are separate mid diastolic and presystolic murmurs while in severe MS, the mid diastolic murmur is long and merges with the presystolic murmur to produce a holodiastolic murmur.
  • Causes of absent MDM in MS-
    • Thick chest wall and emphysema
    • Low cardiac output
    • Marked RV enlargement with RV occupying the apex
  • To increase intensity of MDM-
    • Left lateral position
    • Held expiration
    • Auscultate after walking (isotonic exercise)
    • Isometric exercise
    • Squatting
  • EDM in an MS patient is more likely to be due to AR than PR.
  • Causes of mitral MDM other than MS-
    • MR
    • LA myxoma
    • Ball valve thrombus
    • VSD, PDA
    • HCM

Echocardiography

  • Echocardiographic features of MS-
    • Leaflet thickening
    • Chordal thickening and shortening
    • Commissural fusion
    • Calcification of leaflets and chordae
    • Diastolic doming- due to commissural fusion
  • Wilkins score
    • 4 to 16
    • 4 points each for leaflet thickness, leaflet mobility, leaflet calcification and chordal involvement.
  • TEE in MS-
    • To assess MR severity
    • To rule out LAA clot

Chest radiography-

  • Chest radiography features of MS-
    • Mitral valve- calcification
    • Left atrium-
      • Enlargement- straightening of left heart border, bulge on left heart border, double shadow, bulge on right heart border, elevation of left bronchus causing widening of carinal angle, bulge in barium swallow
      • Calcification of left atrial wall
    • Pulmonary venous hypertension (prominent upper lobe veins- cephalization or whisker sign)
    • Pulmonary capillary hypertension
      • Kerly lines- A, B, C
      • Pulmonary edema
      • Pleural effusion, interlobar effusion
      • Pulmonary hemosiderosis, pulmonary ossification
    • Pulmonary arterial hypertension-
      • Dilated main, right and left pulmonary arteries
      • Pulmonary artery calcification
    • RV and RA enlargement, dilated SVC
  • LA enlargement is more in MR than in MS. PA, RV and RA enlargement are more in MS than in MR.
  • Kerly B lines-
    • Short horizontal lines
    • Costophrenic angles
    • LA pressure more than 20 mmHg
  • Kerly A lines- Long dense lines running to hilum

ECG-

  • LAE
  • RVH (present in half with RVSP 70-100 and in all with RVSP > 100)
  • Right axis deviation

Cardiac catheterization-

  • Indications-
    • With BMV
    • Discrepancy between clinical and echo findings
  • Calculations-
    • Mean gradient across mitral valve
    • Calculation of MVA using Gorlin formula
  • Features of LA pressure tracing in MS-
    • Mean pressure is increased
    • Prominent a wave
    • Slow y descent

Natural history

  • After rheumatic fever, it takes minimum 2 years to develop MS.
  • In US and Europe, severe MS occurs in old age while in India, it occurs in young age and may occur even in children as young as 6 years old.
  • Annual decrease of MVA- 0.09 cm2.
  • Rapid progression of MS- annual decrease of MVA more than 0.1 cm2.
  • 5 year survival in MS in presurgical era-
    • NYHA III- 62%
    • NYHA IV- 15%
  • 5 year survival in symptomatic MS in surgical era, but without intervention- 44%
  • 10 year survival according to NYHA class-
    • I- 85%
    • II- 50%
    • III- 20%
    • IV- very low

Complications-

Atrial fibrillation-

  • Commonest complication of MS
  • Prevalence of AF according to age-
    • Second decade- 10%
    • Third decade- 17%
    • Fourth decade- 45%
    • Fifth decade- 60%
    • Sixth decade and beyond- 80%
  • Incidence of atrial fibrillation in MS roughly parallels the age of the patient.
  • AF worsens symptoms of MS by-
    • Decreasing diastolic filling time- leads to increased LA pressure
    • Loss of atrial contribution to LV filling- leads to increased LA pressure
    • LA thrombus leading to systemic embolization
  • Factors correlating with frequency of AF-
    • Age (strongest)
    • Severity of MS
    • LA diameter
    • LA pressure
  • 5 year survival of AF-
    • Without MS- 85%
    • With MS- 64%
  • AF causes decrease in cardiac output by 20% in MS.

Systemic embolism

  • Causes-
    • LA thrombus
    • IE (rare)
  • Factors predisposing to systemic embolism in MS-
    • AF (present in 80%)
    • Spontaneous echo contrast in LA
    • LA size
    • Age
    • Low cardiac output
  • Clinical features-
    • Cerebral
    • Coronary- leads to chest pain
    • Renal- leads to HT
    • Ball valve or free floating thrombus- syncope in specific body position, variability in physical findings- urgent surgery needed.
  • Incidence of systemic embolism in MS in age less than and more than 35 years is 5% and 11% respectively. That in MS + AF is 27% and 32% respectively.

Infective endocarditis-

  • Less common compared to MR and aortic valve disease

Management-

Medical-

  • Rheumatic fever prophylaxis
  • IE prophylaxis is not needed
  • Indications for anticoagulation in MS-
    • AF (persistent or paroxysmal)
    • Embolic events
    • LA thrombus
    • LA diameter > 55 mm
    • Spontaneous echo contrast
  • Decrease sodium intake
  • Diuretics
  • Beta blockers or non DHP calcium channel blockers to reduce heart rate (even in sinus rhythm, more useful in AF)
  • Digoxin if AF with right heart failure

Percutaneous valvulotomy-

  • Indications for BMV- moderate or severe MS with-
    • Symptoms (NYHA II or more)
    • PA systolic pressure more than 50 mmHg at rest or more than 60 mmHg with exercise
    • New onset AF
  • Contraindications for BMV-
    • Moderate or severe MR
    • Severe calcification
    • Severe subvalvular fibrosis
    • Thrombus in LA or LV
    • Recent embolism
    • Bleeding disorders
    • Interatrial septal thickness more than 3 mm (relative contraindication)
  • Indications for BMV in mitral valve not ideal for BMV-
    • Patients at high risk for surgery due to comorbidities
    • Pregnancy
    • Women wanting to become pregnant
  • Techniques of percutaneous mitral valvotomy-
    • IAS puncture- inoue balloon
    • IAS puncture- two balloon side-by-side
    • Retrograde- using balloon
    • Reusable metallic valvulotome
  • Mechanisms of benefit with BMV-
    • Commissural separation
    • Fracture of nodular calcium
  • Complications-
    • MR severe enough to need surgery- 2%
    • Mortality- 1 to 2%
    • Cardiac perforation- 1%
    • Cerebral embolism- 1%
  • Factors predicting poor outcome with BMV-
    • Calcification, especially of commissures
    • Extensive subvalvular fibrosis
    • Wilkins score more than 8
  • TEE should be done just before BMV
  • Ben Farhat series-
    • 7 year follow-up
    • Follow-up results of BMV and OMV are equal and are better than those of CMV
    • Freedom from reintervention-
      • OMV- 93%
      • BMV- 90%
      • CMV- 50%
  • Balloon size for BMV (in mm)- (height in cm/10) + 10
  • Double balloon BMV was first done by Al Zaibag
  • Need for MVR at 2 years after BMV-
    • 3% if score less than or equal to 8
    • 14% if score more than 8
  • If score in 12 or more, BMV is done only if surgery is not possible
  • BMV gives good result if score is 8 or less
  • BMV should give MVA of more than 1.5 cm2 and gradient less than 7 mmHg.
  • Compared to Inoue balloon, double balloon gives better immediate results. But there is no change in restenosis or survival.
  • BMV is better than CMV because-
    • CMV- blades may not be in commissures
    • BMV- balloon applies uniform pressure

Surgery-

  • Surgical options-
    • CMV
    • OMV
    • MVR
  • Indications- When BMV is not possible due to moderate or severe MR, LA thrombus or leaflet calcification + any one of the following
    • Significant symptoms (NYHA III or IV)
    • Severe PAH
    • Recurrent embolism despite anticoagulation
  • CMV-
    • First done by Bailley
    • Cannot be done with LA thrombus, calcification, severe subvalvular disease or moderate or severe MR
    • Transatrial or transventricular
  • OMV-
    • Preferred to MVR
    • Commissures are incised
    • Concurrent annuloplasty can be done for MR
    • LA thrombus, if present, is removed
    • LA appendage is amputated
    • Calcium in leaflets can be removed
    • Fused chordae are separated
    • Maze procedure is done if needed
    • LA and LV pressures are measured off bypass- if unsatisfactory, MVR is done
    • Restenosis rate after valvotomy (any type)- 20% at 10 years
    • Causes of restenosis after valvotomy (any type)- trauma due to turbulent flow
  • MVR-
    • Loss of annular-papillary muscle continuity can affect LV function
    • Done in cases in which even OMV is not possible
    • Maze procedure is done if needed
    • Operative mortality is 3 to 8%
    • Mechanical prosthesis if age is less than 65 years; bioprosthesis if age is more than 65 years.
    • Presence of AF favors mechanical prosthesis.

Congenital mitral stenosis-

  • Typical type- short chordae- survival 6 months
  • Supravalvular ring- survival 5 years
  • Parachute mitral valve- survival 10 years
  • Anomalous mitral arcade

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