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  • • Fibrous annulus of mitral valve (MV) is thin, incomplete ring of fibrous tissue

    • Most MVs have anterior and posterior leaflets, attached by thin fibrous chordae tendineae to papillary muscle

    • Closed during systole via action of papillary muscle contraction, open during diastole when LA pressure higher than LV pressure

    • Mitral stenosis (MS) is fibrosis, narrowing of valvular area causing ventricular inflow obstruction during diastole

    Early valvular disease of rheumatic fever: Acute inflammatory infiltrate that heals by fibrous organization

    • Leaflets become fibrotic and thickened causing reduced pliability and surface area

    • Fusion of leaflets at commissures

    • Calcification may occur in leaflets

    • Chordae thickened, shortened, and fibrotic

    • Mitral complex becomes "fish mouth"

    • Results in pulmonary congestion, thickening of pulmonary capillaries, intimal fibrosis of arterioles

    • Pulmonary hypertension progresses with time

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Epidemiology

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  • • Causes of valve disease include:

    • -Rheumatic carditis (most common)

      -Valve collagen degeneration

      -Infection

    • Less common causes include:

    • -Collagen-vascular disease

      -Tumors

      -Carcinoid

      -Marfan syndrome

    Valvular heart disease: 89,000 hospital discharges in 1998

    • Number 1 cause of MS is rheumatic fever associated with group A streptococcal pharyngitis

    • Death due to heart failure in up to 70%

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Symptoms and Signs

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  • • Dyspnea (initially with exertion), orthopnea

    • Atrial fibrillation with atrial dilation; often with clinical deterioration due to dependence on atrial kick (20% of cardiac output) and tachycardia

    • Thin cachectic "mitral facies"

    • Jugular pulsations from fluid overload

    • v waves observed if in atrial fibrillation

    • Peripheral edema and hepatic enlargement with "hepatojugular reflux"

    • Pulmonary component of S2 pronounced and may be palpable

    • Opening snap of MV common due to tensing of leaflets by chordae (heard best at apex)

    • Diastolic low pitched rumbling murmur (heard best at apex), accentuated if in sinus rhythm with atrial contraction

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Laboratory Findings

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  • • ECG

    • -90% in sinus rhythm exhibit broad, notched P wave (P mitrale)

      -Later stages: Atrial fibrillation and RV hypertrophy

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Imaging Findings

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  • Chest film

    • -Left atrial enlargement

      -Engorged pulmonary veins and arteries

      -Kerley B lines

      -Pulmonary edema if severe congestive heart failure (CHF)

    Echocardiography: Provides information on valve anatomy and area

    Catheterization: Measure transvalvular gradients/valve area:

    • normal mitral area = 3 cm2/m2 BSA; significant MS ≤ 1 cm2/m2 BSA

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  • • Echocardiography

    • Catheterization

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  • • Echocardiography

    • Catheterization

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  • • Treat asymptomatic patients medically (control heart rate, anticoagulation therapy for atrial fibrillation)

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Surgery

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  • • Percutaneous balloon valvotomy-moderate to severe symptomatic MS; ideal for minimally calcified, no MR

    • Surgical commissurotomy (50%):

    • -Absence of leaflet calcification, better candidate

      -Complete incision of commissures

      -Thickened chordae resected

      -Papillary muscles divided to lengthen

    • MV replacement: If calcified or fibrous retraction, maintain subvalvular attachments to maintain geometry

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Indications

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