Mitral Stenosis

• • 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

Epidemiology

• • 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%

Symptoms and Signs

• • 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

Laboratory Findings

• • ECG

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

    -Later stages: Atrial fibrillation and RV hypertrophy

Imaging Findings

• • 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

• • Echocardiography

  • Catheterization

• • Echocardiography

  • Catheterization

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

Surgery

• • 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