Mitral Stenosis

Key Features

Essentials of Diagnosis

• Fatigue, exertional dyspnea, and orthopnea when the stenosis becomes severe

• Prominent mitral first sound, opening snap (usually), and apical diastolic rumble

• Auscultatory A₂ to opening snap interval shortens as the mitral stenosis worsens (increased LA pressure)

• ECG shows left atrial (LA) abnormality and, commonly, atrial fibrillation

• Echocardiography/Doppler is diagnostic

General Considerations

• Most patients with native valve mitral stenosis are presumed to have had rheumatic heart disease, although a history of rheumatic fever is noted in only about one-third

• Rheumatic mitral stenosis results in

  • Thickening of the leaflets

  • Fusion of the mitral commissures

  • Retraction

  • Thickening and fusion of the chordae

  • Calcium deposition in the valve

• Mitral stenosis can also occur due to congenital disease with chordal fusion or papillary muscle malposition

  • The papillary muscles may be abnormally close together, sometimes so close that they merge into a single papillary muscle (the "parachute mitral valve")

  • In these patients, the chordae or valvular tissue (or both) may also be fused

• In older patients and in those undergoing dialysis,

  • Mitral annular calcification may stiffen the mitral valve and reduce its motion to the point where a mitral gradient is present

  • Calcium in the mitral annulus virtually invades the mitral leaflet from the annulus inward as opposed to the calcium buildup in the leaflets and commissures as seen in rheumatic heart disease

• Mitral valve obstruction may also develop in patients who have had mitral valve repair with a mitral annular ring that is too small, or in patients who have had a surgical valve replacement (prosthetic valve-patient mismatch or degeneration of the prosthetic valve over time)

Clinical Findings

• Symptoms often precipitated by onset of atrial fibrillation or pregnancy

• Most symptomatic patients have a mitral valve area of < 1.5 cm²

• An opening snap following A₂ due to stiff mitral valve

• Interval between opening snap and aortic closure sound is long when the left atrial pressure is low but shortens as left atrial pressure rises and approaches the aortic diastolic pressure

• As mitral stenosis worsens, there is a localized low-pitched diastolic murmur

  • It is best heard at the apex when the patient is in left lateral position

  • Duration increases with the severity of the stenosis as the mitral gradient continues throughout more of diastole

  • Mitral regurgitation may be present as well

• Mild to moderate mitral stenosis (valve area usually between 1.5 cm² and 1.0 cm²):

  • LA pressure and cardiac output may be essentially normal

  • Patient is either asymptomatic or symptomatic only with extreme exertion

• Severe mitral stenosis (valve area < 1.0 cm²): severe pulmonary hypertension develops due to a "secondary stenosis" of the pulmonary vascular bed; in this condition

  • Pulmonary edema is uncommon

  • Symptoms of low cardiac output and right heart ...