Mitral stenosis

Mitral stenosis

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