Mitral Stenosis

Author: Claudia Dima, MD; Chief Editor: Richard A Lange, MD more...

Updated: Nov 1, 2010

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Background
Pathophysiology
Epidemiology
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Background

Mitral stenosis (MS) is characterized by obstruction to left ventricular inflow at the level of mitral valve due to structural abnormality of the mitral valve apparatus. The most common cause of mitral stenosis is rheumatic fever. Other less common etiologies include congenital mitral stenosis, malignant carcinoid disease, systemic lupus erythematosus, rheumatoid arthritis, mucopolysaccharidoses of the Hunter-Hurler phenotype, Fabry disease, Whipple disease, and methysergide therapy. The association of atrial septal defect with rheumatic mitral stenosis is called Lutembacher syndrome.

A number of conditions can simulate the physiology of mitral stenosis: severe nonrheumatic mitral annular calcification, infective endocarditis with large vegetation, left atrial myxoma, ball valve thrombus, or cor triatriatum.

Stenosis of the mitral valve typically occurs decades after the episode of acute rheumatic carditis. Acute insult leads to formation of multiple inflammatory foci (Aschoff bodies, perivascular mononuclear infiltrate) in the endocardium and myocardium. Small vegetations along the border of the valves may also be observed. With time, the valve apparatus becomes thickened, calcified, and contracted, and commissural adhesion occurs, ultimately resulting in stenosis.

Whether the progression of valve damage is due to hemodynamic injury of the already affected valve apparatus or to the chronic inflammatory nature of the rheumatic process is unclear.

Pathophysiology

The normal mitral valve orifice area is approximately 4-6 cm². As the orifice size decreases, the pressure gradient across the mitral valve increases to maintain adequate flow.

Patients will not experience valve-related symptoms until the valve area is 2-2.5 cm² or less, at which point moderate exercise or tachycardia may result in exertional dyspnea from the increased transmitral gradient and left atrial pressure.

Severe mitral stenosis occurs with a valve area of less than 1 cm². As the valve progressively narrows, the resting diastolic mitral valve gradient, and hence left atrial pressure, increases. This leads to transudation of fluid into the lung interstitium and dyspnea at rest or with minimal exertion. Hemoptysis may occur if the bronchial veins rupture and left atrial dilatation increases the risk for atrial fibrillation and subsequent thromboembolism.

Pulmonary hypertension may develop as a result of (1) retrograde transmission of left atrial pressure, (2) pulmonary arteriolar constriction, (3) interstitial edema, or (4) obliterative changes in the pulmonary vascular bed (intimal hyperplasia and medial hypertrophy). As pulmonary arterial pressure increases, right ventricular dilation and tricuspid regurgitation may develop, leading to elevated jugular venous pressure, liver congestion, ascites, and pedal edema.

Left ventricular end-diastolic pressure and cardiac output are usually normal in the person with isolated mitral stenosis. As the severity of stenosis increases, the cardiac output becomes subnormal at rest and fails to increase during exercise. Approximately one third of patients with rheumatic mitral stenosis have depressed left ventricular systolic function as a result of chronic rheumatic myocarditis. The presence of concomitant mitral regurgitation, systemic hypertension, aortic stenosis, or myocardial infarction can also adversely affect left ventricular function and cardiac output.

Frequency

United States

The prevalence of rheumatic disease in developed nations is steadily declining with an estimated incidence of 1 in 100,000.

International

The prevalence of rheumatic disease is higher in developing nations than in the United States.^[1]In India, for example, the prevalence is approximately 100-150 cases per 100,000, and in Africa the prevalence is 35 cases per 100,000.

Mortality/Morbidity

Mitral stenosis is a progressive disease consisting of a slow, stable course in the early years followed by an accelerated course later in life. Typically, there is a latent period of 20-40 years from the occurrence of rheumatic fever to the onset of symptoms. Once symptoms develop, it is almost a decade before they become disabling. In some geographic areas, mitral stenosis progresses more rapidly, presumably due to either a more severe rheumatic insult or repeated episodes of rheumatic carditis due to new streptococcal infections, which results in severe symptomatic mitral stenosis in the late teens and early 20s.

In the asymptomatic or minimally symptomatic patient, survival is greater than 80% at 10 years. When limiting symptoms occur, 10-year survival is less than 15% in the patient with untreated mitral stenosis. When severe pulmonary hypertension develops, mean survival is less than 3 years. Most (60%) patients with severe untreated mitral stenosis die of progressive pulmonary or systemic congestion, but others may suffer systemic embolism (20-30%), pulmonary embolism (10%), or infection (1-5%).

Sex

Two thirds of all patients with rheumatic mitral stenosis are female.

Age

The onset of symptoms usually occurs between the third and fourth decade of life.

Proceed to Clinical Presentation

Contributor Information and Disclosures

Author

Claudia Dima, MD Cardiovascular Fellow, Department of Cardiology, Banner Good Samaritan Medical Center

Disclosure: Nothing to disclose.

Coauthor(s)

Kenneth B Desser, MD Clinical Professor, Director of Cardiology Fellowship, Banner Good Samaritan Medical Center, Phoenix, Arizona

Disclosure: Nothing to disclose.

Specialty Editor Board

L Michael Prisant, MD, FACC, FAHA Cardiologist, Emeritus Professor of Medicine, Medical College of Georgia

L Michael Prisant, MD, FACC, FAHA is a member of the following medical societies: American College of Cardiology, American College of Chest Physicians, American College of Clinical Pharmacology, American College of Forensic Examiners, American College of Physicians, American Heart Association, and American Medical Association

Disclosure: Boehringer-Ingelheim Honoraria Speaking and teaching

Francisco Talavera, PharmD, PhD Senior Pharmacy Editor, eMedicine

Disclosure: eMedicine Salary Employment

Steven J Compton, MD, FACC, FACP Director of Cardiac Electrophysiology, Alaska Heart Institute, Providence and Alaska Regional Hospitals

Steven J Compton, MD, FACC, FACP is a member of the following medical societies: Alaska State Medical Association, American College of Cardiology, American College of Physicians, American Heart Association, American Medical Association, and Heart Rhythm Society

Disclosure: Nothing to disclose.

Amer Suleman, MD Consultant in Electrophysiology and Cardiovascular Medicine, Department of Internal Medicine, Division of Cardiology, Medical City Dallas Hospital

Amer Suleman, MD is a member of the following medical societies: American College of Physicians, American Heart Association, American Institute of Stress, American Society of Hypertension, Federation of American Societies for Experimental Biology, Royal Society of Medicine, and Society of Cardiac Angiography and Interventions

Disclosure: Nothing to disclose.

Chief Editor

Richard A Lange, MD Professor and Executive Vice Chairman, Department of Medicine, Director, Office of Educational Programs, University of Texas Health Science Center at San Antonio

Richard A Lange, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Cardiology, American Heart Association, and Association of Subspecialty Professors

Disclosure: Nothing to disclose.

References

Marcus RH, Sareli P, Pocock WA, et al. The spectrum of severe rheumatic mitral valve disease in a developing country. Correlations among clinical presentation, surgical pathologic findings, and hemodynamic sequelae. Ann Intern Med. Feb 1 1994;120(3):177-83. [Medline].
Bruce CJ, Nishimura RA. Newer advances in the diagnosis and treatment of mitral stenosis. Curr Probl Cardiol. Mar 1998;23(3):125-92. [Medline].
[Guideline] Gerber MA, Baltimore RS, Eaton CB, Gewitz M, Rowley AH, Shulman ST, et al. Prevention of rheumatic fever and diagnosis and treatment of acute Streptococcal pharyngitis: a scientific statement from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee of the Council on Cardiovascular Disease in the Young, the Interdisciplinary Council on Functional Genomics and Translational Biology, and the Interdisciplinary Council on Quality of Care and Outcomes Research: endorsed by the American Academy of Pediatrics. Circulation. Mar 24 2009;119(11):1541-51. [Medline].
Antonini-Canterin F, Moura LM, Enache R, Leiballi E, Pavan D, Piazza R. Effect of hydroxymethylglutaryl coenzyme-a reductase inhibitors on the long-term progression of rheumatic mitral valve disease. Circulation. May 18 2010;121(19):2130-6. [Medline].
[Guideline] Nishimura RA, Carabello BA, Faxon DP, Freed MD, Lytle BW, O'Gara PT. ACC/AHA 2008 Guideline update on valvular heart disease: focused update on infective endocarditis: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines endorsed by the Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. J Am Coll Cardiol. Aug 19 2008;52(8):676-85. [Medline].
Feldman T. Rheumatic Mitral Stenosis. Curr Treat Options Cardiovasc Med. Apr 2000;2(2):93-104. [Medline].
Rahimtoola SH. Choice of Prosthetic Heart Valve in Adults An Update. J Am Coll Cardiol. Jun 1 2010;55(22):2413-2426. [Medline].
Horstkotte D, Niehues R, Strauer BE. Pathomorphological aspects, aetiology and natural history of acquired mitral valve stenosis. Eur Heart J. Jul 1991;12 Suppl B:55-60. [Medline].
[Guideline] Bonow RO, Carabello BA, Chatterjee K, de Leon AC Jr, Faxon DP, Freed MD, et al. 2008 focused update incorporated into the ACC/AHA 2006 guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to revise the 1998 guidelines for the management of patients with valvular heart disease). Endorsed by the Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. J Am Coll Cardiol. Sep 23 2008;52(13):e1-142. [Medline].
Bonow RO, Otto CM. Valvular heart disease. In: Libby P, Bonow RO, Mann DL, Zipes DP. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 2. 8^th ed. Philadelphia, PA: WB Saunders; 2008:1646-1657.
Carabello BA. Modern management of mitral stenosis. Circulation. Jul 19 2005;112(3):432-7. [Medline].

M-mode across the mitral valve showing a flat E-F slope resulting from elevated left atrial pressure throughout diastole due to a significant gradient across the mitral valve. Increased thickness and calcification of anterior leaflet of the mitral valve and decreased opening of the anterior and posterior leaflets in diastole are also shown.

Parasternal long-axis view demonstrating calcification and doming in diastole of the anterior valve leaflet and mild restriction in the opening of posterior mitral valve leaflet.

Apical 4-chamber view demonstrating restricted opening of the anterior and posterior mitral valve leaflet with diastolic doming of anterior leaflet with left atrial enlargement.

Transesophageal echocardiogram with continuous wave Doppler interrogation across the mitral valve demonstrating an increased mean gradient of 16 mm Hg consistent with severe mitral stenosis.

Apical 4-chamber view with color Doppler demonstrating aliasing in the atrial side of the mitral valve consistent with increased gradient across the valve. This figure also shows mitral regurgitation and left atrial enlargement.

Magnified view of the mitral valve in apical 4-chamber view revealing restricted opening of both leaflets.

Transesophageal echocardiogram in an apical 3-chamber view showing calcification and doming of the anterior mitral leaflet and restricted opening of both leaflets.

Transesophageal echocardiogram in an apical 3-chamber view with color Doppler interrogation of the mitral valve revealing aliasing, which is consistent with increased gradient across the mitral valve secondary to stenosis. Also shown in this image, a posteriorly directed jet of severe mitral regurgitation.

Table 1. Duration of Secondary Rheumatic Fever Prophylaxis

Category	Duration After Last Attack	Rating*
Rheumatic fever with carditis and residual heart disease (persistent valvular disease† )	10 y or until age 40 y (whichever is longer); sometimes lifelong prophylaxis	IC
Rheumatic fever with carditis but no residual heart disease (no valvular disease† )	10 y or until age 21 y (whichever is longer)	IC
Rheumatic fever without carditis	5 y or until age 21 y (whichever is longer)	IC
*Rating indicates classification of recommendation and level of evidence (eg, IC indicates Class I, level of Evidence C). †Clinical or echocardiographic evidence.

Table 2. Secondary Prevention of Rheumatic Fever (Prevention of Recurrent Attacks)

Agent	Dose	Mode	Rating*
Benzathine penicillin G	Children 27 kg (60 lb): 600,000 U Patients >27 kg: 1,200,000 every 4 wk†	Intramuscular	IA
Penicillin V	250 mg bid	Oral	IB
Sulfadiazine	Children 27 kg: 0.5 g qd Patients >27 kg: 1 g qd	Oral	IB
Macrolide or azalide (for individuals allergic to penicillin and sulfadiazine)	Variable	Oral	IC
*Rating indicates classification of recommendation and level of evidence (eg, IA indicates Class I, level of Evidence A). †In high-risk situations, administration every 3 weeks is justified and recommended.

Table 3. Primary Prevention of Rheumatic Fever (Treatment of Streptococcal Tonsillopharyngitis*)

Agent	Dose	Mode	Duration	Rating †
Penicillins
Penicillin V (phenoxymethyl penicillin)	Children 27 kg (60 lb): 250 mg bid or tid Patients >27 kg: 500 mg bid or tid	Oral	10 d	IB
Amoxicillin	50 mg/kg qd (maximum 1 g)	Oral	10 d	IB
Benzathine penicillin G	Children 27 kg (60 lb): 600,000 U Patients >27 kg: 1,200,000 U	Intramuscular	Once	IB
For individuals allergic to penicillin
Narrow-spectrum cephalosporin (cephalexin, cefadroxil)	Variable	Oral	10 d	IB
Clindamycin	20 mg/kg/d divided in 3 doses (maximum 1.8 g/d)	Oral	10 d	IIaB
Azithromycin	12 mg/kg qd (maximum 500 mg)	Oral	5 d	IIaB
Clarithromycin	15 mg/kg/d divided bid (maximum 250 mg bid)	Oral	10 d	IIaB
*Sulfonamides, trimethoprim, tetracyclines, and fluoroquinolones are not acceptable. † Rating indicates classification of recommendation and level of evidence (eg, IB indicates Class I, level of Evidence B)

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