AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

INTRODUCTION

Section 2 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Background

Mitral stenosis (MS) is a narrowing of the inlet valve into the left ventricle that prevents proper opening during diastolic filling. Patients with mitral stenosis typically have mitral valve leaflets that are thickened, commissures that are fused, and/or chordae tendineae that are thickened and shortened.

The most common cause of mitral stenosis is rheumatic fever (RF). Approximately 40% of patients with rheumatic heart disease have isolated mitral stenosis. Conversely, rheumatic involvement is present in 99% of stenotic mitral valves excised at the time of mitral valve replacement. RF, however, is exceedingly rare nowadays. It has been more than 10 years since the Centers for Disease Control and Prevention (CDC) discontinued mandatory reporting of acute RF. Studies in the 1950s during an epidemic on a military base demonstrated a 3% incidence of RF in adults with streptococcal pharyngitis not treated with antibiotics. Studies in children during the same period demonstrated an incidence of only 0.3%.

After the initial episode of RF, a latency period of 20-40 years occurs until the onset of symptoms. The natural history of mitral stenosis is typically progressive, with a slow and stable course early on, followed by progressive acceleration in the later years.

Pathophysiology

The serum of patients with RF contains antibodies to the type 5 streptococcal M protein, which cross-reacts with myocardial tissue. Pathologic examination of the mitral valve at this time reveals proliferation of fibroblasts and macrophages.

Subsequent disease may occur as a consequence of the healing of the rheumatic process, subclinical repetitive rheumatic insults, chronic rheumatic activity, or progressive hemodynamic stresses on the traumatized valve, similar to that of aortic stenosis. The plethora of postulated mechanisms for this pathologic evolution may account for the fact that some patients experience a chronic stable disease, while others have an accelerated course necessitating early surgical intervention.

The normal area of the mitral valve orifice is 4-6 cm², which effectively creates a common chamber between the left atrium and the left ventricle in diastole. In early diastole, a small and brief pressure gradient is present, but, during most of the filling period, the pressures in the 2 chambers are equal. Narrowing of the valve area to less than 2.5 cm² impedes the free flow of blood and causes a build up of left atrial pressure (LAP) to promote normal transmitral flow volume.

Critical mitral stenosis occurs when the opening is reduced to 1 cm². At this stage, a LAP of 25 mm Hg is required to maintain a normal cardiac output. With progressive stenosis, critical flow restriction reduces left ventricular output. The increase in LAP also enlarges the left atrium and raises pulmonary venous and capillary pressures. The resulting pulmonary congestion and reduced cardiac output can mimic primary left ventricular failure, but left ventricular contractility is normal in most cases of mitral stenosis. As the disease evolves, chronic elevation of LAP eventually leads to pulmonary hypertension, tricuspid and pulmonary valve incompetence, and secondary right heart failure.

Frequency

United States

The prevalence of mitral stenosis has decreased because of the decline in RF. Antibiotic treatment of strep throat may be partially responsible for the decline. Early trials demonstrated that penicillin treatment of streptococcal pharyngitis is effective in preventing acute RF (relative risk [RR], 0.28; number needed to treat [NNT], 63) in the samples studied. However, the incidence of acute RF in these trials was much higher in both treated and control groups than is seen today; the reported incidence per population was approximately 60 times greater in 1965 than in 1994 and the NNT today would be close to 4000.

Although the true incidence of disease is not known, about 1500 balloon mitral valvotomies were performed in the United States in 2004. This number serves as a rough index of severe disease prevalence.

International

Both RF and mitral stenosis remain common in developing nations, and progression of mitral stenosis tends to be more rapid in these areas.

Mortality/Morbidity

Overall, the 10-year survival of untreated patients with mitral stenosis is 50-60%, depending on symptoms at presentation.

Without surgical intervention, the 20-year mortality is 85%.

In untreated patients, the causes of death are as follows:

• Progressive heart failure in 60-70%
• Systemic embolism in 20-30%, pulmonary embolism in 10%
• Infection in 1-5%

Sex

Although the attack rate for RF is roughly equal among genders, mitral stenosis is 2-3 times more common in women than in men.

Age

Except in developing countries where the disease is more aggressive and the course can be accelerated, the onset of symptoms usually is between the fourth and fifth decades of life. Occasionally, patients can become symptomatic before age 20 years.

CLINICAL

Section 3 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

History

Inquire about the history of acute RF, although 50-60% of patients do not recall this. Also inquire about history of repeated streptococcal pharyngitis or scarlet fever in childhood.

• Many patients are asymptomatic. Some patients may develop symptoms during physiologic stress such as infection, exercise, fever, or pregnancy.
• Exertional dyspnea, orthopnea, and paroxysmal nocturnal dyspnea (symptoms of left heart failure) are most common. Dyspnea may be accompanied by cough and wheezing. Attacks of frank pulmonary edema may occur.
• Chest pain due to right ventricular ischemia, concomitant coronary atherosclerosis, or a coronary embolism may be present.
• Hemoptysis from pulmonary venous hypertension results in rupture of anastomosis between bronchial veins.
• Ortner syndrome may occur if an enlarged left atrium impinges on the left recurrent laryngeal nerve, causing hoarseness.
• Patients may present with complications of mitral stenosis.
• • New-onset atrial fibrillation
  • Systemic embolism
  • Infective endocarditis

Physical

Look for findings not only intrinsic to valvular deformity but also hemodynamic disturbance from the stenotic valve and its complications.

• Cardiac examination of stenotic mitral valve (best at the apex with the patient in the left lateral recumbent position)
• • Palpable diastolic thrill
  • An accentuated S₁, followed by S₂, and an opening snap (OS)
  • Characteristic diastolic low-pitched, rumbling murmur
  • The duration, and not intensity, of the murmur is a guide to the severity of mitral valve narrowing. However, murmur may diminish in intensity as the stenosis increases.
  • The OS and diastolic murmur are often reduced during inspiration and augmented during expiration. Amyl nitrite inhalation, coughing, isometric or isotonic exercise, and sudden squatting all are useful in accentuating a faint or equivocal murmur of mitral stenosis.
• Signs of left heart failure
• • Respiratory distress, evidence of pulmonary edema (eg, rales)
  • Digital clubbing
• Signs of right heart strain/failure
• • Right ventricular lift may be felt. A loud pulmonic closure (P₂) may be noted in the left parasternal region in patients with pulmonary hypertension.
  • Jugular venous distention, ascites, hepatomegaly, and peripheral edema may be noted.
  • Auscultation may reveal a systolic murmur of TR, a Graham Steele murmur of PR (a high-pitched, decrescendo, diastolic murmur of pulmonary insufficiency), and an S₄.
• Signs of complications from mitral stenosis
• • Endocarditis - Fever, murmur, and classically splinter hemorrhage, petechiae, Roth spots, Osler nodes, or Janeway lesions
  • Atrial fibrillation
  • Systemic embolization
• Other findings
• • A holosystolic murmur of mitral regurgitation may accompany the valvular deformity of mitral stenosis.
  • "Mitral facies" characterized by pinkish purple patches on the cheeks may be present.

Causes

• Rheumatic fever (most common, all others are rare)
• Congenital mitral stenosis
• Systemic lupus erythematosus (SLE)
• Rheumatoid arthritis (RA)
• Malignant carcinoid
• Mucopolysaccharidoses (of the Hunter-Hurler phenotype)
• Fabry disease
• Whipple disease
• Methysergide therapy

DIFFERENTIALS

Section 4 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Other Problems to be Considered

Atrial myxoma (obstructing left atrial outflow)
Lutembacher syndrome (congenital atrial septal defect associated with mitral stenosis)
Infective endocarditis with large vegetations

WORKUP

Section 5 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Lab Studies

• Ruling out other diseases is useful.

Imaging Studies

• Two-dimensional (2D) and Doppler echocardiography (Echo) is the diagnostic study of choice.
• • 2D echocardiography evaluates the morphology of the mitral valve, measuring orifice size and detailing leaflet mobility, thickness, calcification, fusion, and appearance of the commissures. It provides anatomic and functional information on cardiac chambers and facilitates recognition of other structural abnormalities.
  • Doppler echocardiography is the most accurate noninvasive technique to quantify the hemodynamic severity of mitral stenosis at rest or with exercise. It measures transvalvular pressure gradient and pulmonary arterial pressure and determines whether mitral regurgitation, aortic regurgitation, and other valvular abnormalities coexist.
  • If a question exists about the diagnosis after transthoracic echocardiography, a transesophageal echocardiography (TEE) provides better images of the mitral valve and is a more sensitive way to detect pathology such as valvular vegetations or atrial thrombus.
• Chest radiography
• • Look for left atrial, pulmonary artery, right ventricle, and/or right atrium enlargement (eg, straightening of left heart border, loss of aortic window).
  • Rarely, calcification of the mitral valve may be seen.
  • Radiologic changes in the lung fields indirectly reflect the severity of mitral stenosis.
  • Interstitial edema manifests as Kerley B lines.
  • Severe, long-standing mitral obstruction results in Kerley A lines and findings of pulmonary hemosiderosis.
  • Pulmonary edema is seldom evident on the chest radiography.

Other Tests

• ECG is relatively insensitive for mild mitral stenosis.
• • Ninety percent of patients with significant mitral stenosis and sinus rhythm display electrical evidence of left atrial enlargement: P-mitrale in lead II and/or a biphasic P wave in lead V₁ with a wide negative deflection greater than 0.04 seconds.
  • The QRS axis in the frontal plane correlates with the severity of valve obstruction in pure mitral stenosis. A mean axis between 0 and +60 degrees suggests a mitral valve area >1.3 cm², whereas an axis of more than 60 degrees suggests a valve area <1.3 cm².
  • Atrial fibrillation usually develops in the presence of preexisting left atrial enlargement.
  • With severe pulmonary hypertension, right-axis deviation and right ventricular hypertrophy can be seen. The ECG of right ventricular hypertrophy typically shows tall R waves in the right chest leads, and the R wave may be taller than the S wave in lead V₁. In addition, right-axis deviation and right precordial T-wave inversions are often present.

Procedures

• Cardiac catheterization
• • Cardiac catheterization is indicated when a discrepancy exists between Doppler-derived hemodynamics and the clinical status in a symptomatic patient.
  • For class 1 indication, perform percutaneous mitral balloon valvotomy in properly selected patients (1998 ACC/AHA Practice Guidelines).
  • Cardiac catheterization measures absolute left- and right-sided pressure when pulmonary artery pressure elevation is out of proportion to mean gradient and valve area.
  • Coronary angiography may be performed in selected patients.

TREATMENT

Section 6 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Emergency Department Care

The goal is to control symptoms, to prevent or retard disease progression, and to treat complications.

• Control symptoms. Treat elevated pulmonary venous pressure, LV systolic dysfunction, and heart failure.
• • Patients with severe mitral stenosis should maintain an upright posture and avoid strenuous physical activity.
  • Sodium intake should be restricted, and maintenance doses of oral diuretics should be continued.
  • The data on beta-blockers are conflicting; beta-blockade may be useful for patients with exertional symptoms if the symptoms occur primarily at high heart rates.
  • Transfusion may be needed for blood loss due to severe hemoptysis.
• Prevent or retard disease. Primary and/or secondary prophylaxis against streptococci/endocarditis should be administered.
• Manage atrial fibrillation and embolic events.
• • Rate control should be maintained with digitalis, a beta-blocker, or a calcium channel blocker. Digitalis works well but has a slow onset of action. A calcium channel blocker may become the preferred agent for its lower tendency to convert the rhythm and risk embolization.
  • If the patient is unstable and immediate cardioversion is indicated (synchronized 100J, 200J, 300J, then 360J monophasic, or biphasic equivalent, with prior sedation), then heparin should be administered before, during, and after cardioversion. Otherwise, electrical or chemical cardioversion should be performed after 3 weeks of warfarin anticoagulation.
  • Anticoagulation is necessary in patients who are unable to maintain normal sinus rhythm.
  • Anticoagulation is also beneficial for cases with normal sinus rhythm with a prior embolic event or a left atrial dimension greater than 55 mm Hg noted by echocardiography.

Consultations

• Cardiologist and/or cardiac thoracic surgeon
• • Known or suspected cases of mitral stenosis with hemodynamic instability, arrhythmia, or embolization
  • Cases involving a new onset or progression of symptoms

MEDICATION

Section 7 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

The goal of medical therapy is to control the rapid ventricular rate.

Drug Category: Antiarrhythmics

These agents alter the electrophysiologic mechanisms that are responsible for arrhythmia.

Drug Category: Beta-adrenergic blockers

These drugs inhibit chronotropic, inotropic, and vasodilatory responses to beta-adrenergic stimulation.

Drug Category: Calcium channel blockers

In specialized conducting and automatic cells in the heart, calcium is involved in the generation of the action potential. The calcium channel blockers inhibit movement of calcium ions across the cell membrane, depressing both impulse formation (automaticity) and conduction velocity.

FOLLOW-UP

Section 8 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Further Inpatient Care

• Balloon valvotomy is, in general, the initial procedure of choice for symptomatic patients with moderate-to-severe mitral stenosis. It can double the mean valve area with a 50-60% decrease in transmitral gradient, producing a prominent and sustained symptomatic improvement.
• • The 1998 ACC/AHA Practice Guidelines gave a class I recommendation for symptomatic patients (New York Heart Association Functional Class, or NYHA FC, II, III, or IV), moderate or severe mitral stenosis (mitral valve are £1.5 cm²), and valve morphology favorable for percutaneous balloon valvotomy in the absence of left atrial thrombus or moderate-to-severe mitral stenosis.
  • In indicated patients, it has proven superior to closed commissurotomy in some long-term studies. The overall event-free (from death, repeat valvotomy, or valve replacement) survival is 80-90% in patients with favorable valve morphology. More than 90% of patients free of events remain in NYHA FC I or II.
• In general, surgical commissurotomy, either open or closed, has similar efficacy to balloon valvotomy.
• • The 1998 ACC/AHA Practice Guidelines gave a class I recommendation for patients with NYHA FC III-IV symptoms, moderate or severe mitral stenosis, and valve morphology favorable for repair if one of the following exists:
    
    
    • Percutaneous mitral balloon valvotomy is not available
    • A left atrial thrombus is present despite anticoagulation
    • A nonpliable or calcified valve with the decision to proceed with either repair or replacement made at the time of the operation
• Mitral valve replacement is performed if patients are not candidates for surgical commissurotomy or percutaneous mitral valvotomy.

Deterrence/Prevention

• Primary prophylaxis consists of an early diagnosis of group A streptococcal pharyngitis. Treatment started within 7-9 days after onset of illness may prevent RF.
• The prevention of repeated attacks may delay the progression of mitral stenosis. Secondary prophylaxis may be individually tailored.
• • With carditis, secondary prevention continues for 10 years or until age 25 years.
  • Without carditis, secondary prevention continues for 5 years or until age 18 years.
• Lifelong endocarditis prophylaxis is recommended for procedures that may cause transient bacteremia, including teeth cleaning and other dental procedures that may cause gum bleeding, ENT surgeries, bronchoscopy, prostate surgeries, urethral dilatation, and cystoscopy. In the nonallergic patient, amoxicillin is recommended for dental and airway procedures, while ampicillin plus gentamicin is indicated for genitourinary procedures.

Complications

• Thromboembolism
• Atrial fibrillation
• Bacterial endocarditis
• Pulmonary hypertension
• Pulmonary edema
• Complications of balloon valvulotomy (eg, stroke, cardiac perforation, development of mitral regurgitation)
• Complications of mitral valve replacement (eg, paravalvular leakage, thromboembolism, infective endocarditis, mechanical dysfunction, bleeding due to anticoagulants)

Prognosis

• Depends on severity of symptoms (by the NYHA functional class), the 10-year survival is as follows:
• • 85% for no symptom (class I)
  • 34-42% for mild symptoms (early class II)
  • 40% for moderate-severe symptoms (late class II, class III)
  • 0% for class IV (Of class IV patients, survival is 42% at 1 year and 10% at 5 years.)
• The operative mortality rate is 1-2% for mitral commissurotomy and 2-5% for mitral valve replacement.

MISCELLANEOUS

Section 9 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical/Legal Pitfalls

• The severity of disease is underestimated during periods of tachycardia because a decrease in cardiac output leads to a decrease in the intensity of the murmur.
• Failure to give antibiotic prophylaxis for beta-hemolytic streptococcal infections and prophylaxis for infective endocarditis to patients with mitral valve disease may result in litigation.
• Failure to aggressively treat anemia or infections in patients with mitral stenosis could lead to litigation.

MULTIMEDIA

Section 10 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Media file 1:  Mitral stenosis.
	View Full Size Image
Media type:  Photo

REFERENCES

Section 11 of 11

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

• ACC/AHA Task Force Report. ACC/AHA Guidelines for the Management of Patients with Valvular Heart Disease. A Report of the American College of Cariology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Patients with valvular Disease). JACC. 1998:1486-588.
• Bonow RO, Braunwald E. Valvular heart disease. In Zipe's: Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 7th ed. WB Saunders Co;2005:1553-63.
• Braunwald E. Valvular heart disease. In: Harrison's Principles of Internal Medicine. 16th ed. 2005;chap 219.
• Carabello BA, Crawford FA. Valvular heart disease. N Engl J Med. Jul 3 1997;337(1):32-41. [Medline].
• Carabello BA. Modern management of mitral stenosis. Circulation. Jul 19 2005;112(3):432-7. [Medline].
• Chiang CW, Lo SK, Ko YS, et al. Predictors of systemic embolism in patients with mitral stenosis. A prospective study. Ann Intern Med. Jun 1 1998;128(11):885-9. [Medline].
• Cline DM. Valvular emergencies. In: Tintinalli's Emergency Medicine: A Comprehensive Study Guide. 6th ed. McGraw-Hill Co Inc;2004:chap 54.
• Cooper RJ, Hoffman JR, Bartlett JG, et al. Principles of appropriate antibiotic use for acute pharyngitis in adults: background. Ann Emerg Med. Jun 2001;37(6):711-9. [Medline].
• Janz TG. Valvular heart disease: clinical approach to acute decompensation of left-sided lesions. Ann Emerg Med. Mar 1988;17(3):201-8. [Medline].
• Lung B, Gohlke-Barwolf C, Tornos P, et al. Working Groups Report: Recommendations on the management of the asymptomatic patient with valvular heart disease. Eur Heart J. Aug 2002;23(16):1252-66. [Medline].
• Massie BM, Granger CB, McPhee SJ. Valvular heart disease. In: Tierney's: Current Medical Diagnosis & Treatment. 2005, Online Eds.
• Rahimtoola SH, Dell'Italia LJ. Mitral valve disease. In: Fuster's: Hurst's The Heart. 11th ed. McGraw-Hill Medical Publishing Division;2004:chap 67.
• Rahimtoola SH, Durairaj A, Mehra A. Current Evaluation and Management of Patients with Mitral Stenosis. Circulation. 2002;106:1183-88. [Medline].
• Reyes VP, Raju BS, Wynne J, et al. Percutaneous balloon valvuloplasty compared with open surgical commissurotomy for mitral stenosis. N Engl J Med. Oct 13 1994;331(15):961-7. [Medline].
• Selzer A, Cohn KE. Natural history of mitral stenosis: a review. Circulation. Apr 1972;45(4):878-90. [Medline].
• Shipton B, Wahba H. Valvular heart disease: review and update. Am Fam Physician. Jun 1 2001;63(11):2201-8. [Medline].
• Stoltz C, Bryg RJ. Mitral stenosis. In: Crawford's: Current Diagnosis & Treatment in Cardiology. 2nd ed. McGraw-Hill Co;2003:chap 10.

Article Last Updated: Mar 28, 2006