Mitral Stenosis

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Introduction

Mitral stenosis is a narrowing of the mitral valve, located between the left ventricle and left atrium, preventing full opening during diastole. The most common cause is rheumatic fever, a condition with decreasing incidence in the developed world.

 

 

The Case of Frieda Salas

Frieda Salas is a 64 year-old woman who develops palpitations and worsening shortness of breath over two months. Her family doctor performs a history and physical exam and becomes concerned about the possibility of mitral stenosis.

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Causes and Risk Factors

2/3 of people with mitral stenosis are female.

Rheumatic fever due to Strep. pyogenes infection occurring on average 20 years before cardiovascular symtoms, is the primary cause.

Mitral stenosis due to other causes is rare. These can include:

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Pathophysiology

 

severity

opening diameter

mean gradient (mm Hg)

mild

> 1.5 cm2

< 5

moderate

1.0 - 1.5 cm2

5 - 10

severe

< 1.0 cm2

> 10

Mitral stenosis represents a thickening, fibrosis, and calcifiaction of the valve leaflets. The chordae tendineae can also be thickened and shortened. The normal valve surface area is 4-5 cm2, which effectively creates a common chamber between the left atrium and the left ventricle in diastole. Symptoms typically do not begin until valve area reaches 1.5 cm2, and an opening of 1 cm2 represents a critical narrowing.

 

Rheumatic fever precedes almost all cases of mitral stenosis, most likely due to cross reaction of heart tissue with antibodies against streptococcal M protein. Antibody deposition leads to proliferation of fibroblasts and macrophages.

 

Further damage can result from further infections, chronic disease development, and hemodynamic damage. Some patients develop stable disease, while other experience progressive worsening.

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Signs and Symptoms

  • history
  • physical exam

History

Many patients are asymptomatic.

 

Symptoms of mitral stenosis include:

  • dyspnea (#1 complaint)
  • exercise intolerance
  • cough, hemoptysis
  • chest pain
  • fatigue
  • orthopnea, PND
  • syncope
  • palpitations
  • peripheral edema
  • hoarseness (enlarged LA pressing on recurrent laryngeal nerve)

Physical Exam

Complete a thorough cardiovascular exam.

palpation

  • low pulse volume
  • tapping apex with palpable S1
  • opening snap
  • RV lift
  • palpable S2/P2

 

auscultation

  • loud S1 - as loud as S2 in aortic area
  • opening snap
  • A2 to OS interval inversely proportional to severity
  • diastolic murmur (aka rumble)
    • stretches from the opening snap (after S2) to S1, with pre-systolic accentuation (which would disappear in atrial fibrillation)
    • accentuated with coughing, exercise, squatting
  • in severe mitral stenosis, S1, OS, and rumble may be inaudible

Signs of congestive heart failure and endocarditis may also be present.

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Investigations

  • lab investigations
  • diagnostic imaging

Lab Investigations

Labs are helpful for ruling out other conditions in patients presenting with dysnpea, chest pain, or other symptoms:

  • cardiac enzymes for myocardial infarction
  • BNP for congestive heart failure

Diagnostic Imaging

ECG (not very specific)

  • LAE: biphasic P waves in V1
  • RVH: R waves bigger than S waves in V1 and V2
  • premature contractions
  • atrial flutter/fibrillation

 

CXR

  • LA enlargement
  • pulmonary vascular redistribution

 

Echocardiography is diagnostic

  • smoke in LA visible is a sign of poor prognosis

 

 

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Differential Diagnosis

Differential diagnosis includes:

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Treatments

For acute presentation of heart failure, ischemia, or atrial fibrillation, treat according to ABCs. Treatment options include:

Long-term treatment of CHF, AF, and IHD should be carried out.

Anemia and infections should be screened for and treated.

 

Antibiotic prophylaxis should be given in some situations...

 

Balloon valvuloplasty is helpful for moderate to severe disease in patients with pliable valves, in the absence of thrombi or mitral regurgitation.

 

Mitral valve replacement should be offered to patients with moderate or severe mitral valve regurgitation.

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Consequences and Course

Conditions can worsen with:

 

Increasing elevation of left arterial pressure can lead to:

 

Survival is correlated with symptoms.

At 10 years, survival based on NYHA class:

For people who are asymptomatic, offer yearly history, physical, ECG, and CXR.

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Resources and References

eMedicine article

 

 

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Topic Development

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