Acquired Mitral Stenosis 

Updated: Apr 29, 2014
Author: M Silvana Horenstein, MD; Chief Editor: Stuart Berger, MD 

Overview

Background

Acquired mitral stenosis (MS), or mitral valve stenosis, is virtually synonymous with rheumatic heart disease. In genetically susceptible individuals, rheumatic fever occurs as a complication of group A streptococcal infection. Other rare causes of acquired MS include carcinoid causes, systemic lupus erythematosus, rheumatoid arthritis, and some mucopolysaccharidoses. The underlying pathological process is a diffuse inflammation of connective tissue.

Not all group A streptococcal infections lead to rheumatic fever. Studies demonstrate that rheumatic fever follows infection of the upper respiratory tract and rarely, if ever, follows skin infection. Similarly, not all cases of streptococcal pharyngitis lead to rheumatic fever. In fact, only 2-3% of patients with untreated group A streptococcal pharyngitis develop this complication. Appropriate treatment of streptococcal pharyngitis prevents rheumatic fever.

Rheumatic heart disease primarily affects the mitral valve; mitral regurgitation (MR), or mitral valve regurgitation, is the initial hemodynamic consequence. Lesions of the mitral valve begin as deposits of fibrin and RBCs that form small verrucae along the borders of the mitral valve leaflets. When the inflammation subsides, the verrucae are replaced by fibrous tissue. Over at least several years, the individual may then develop fibrosis of the mitral ring; contracture of the mitral leaflets, chordae tendineae, and papillary muscles; and commisural adhesions that result in valve stenosis. Therefore, rheumatic heart disease is a lifelong and sometimes progressive disease.

Definition

Mitral valve stenosis results from a pathologic process that narrows the effective mitral valve orifice. Proper function of the mitral valve requires an intact mitral valve apparatus and satisfactory left ventricle (LV) function.

Anatomy

The mitral valve is the inlet valve to the LV. The normal mitral valve is a complex apparatus composed of an annulus and two leaflets that are attached to two papillary muscles by chordae tendineae. The papillary muscles arise from the walls of the LV and secure the chordae and mitral leaflets, preventing prolapse of the valve during ventricular systole.

Anatomy of subtypes

Mitral valve stenosis, such as is seen in rheumatic fever, occurs because of fibrous scarring of the valve leaflets with subsequent calcification, thereby decreasing the size of the effective valve orifice. Subvalvular and supravalvular MS are congenital anomalies (see Mitral Stenosis, Congenital).

Pathophysiology

The normal adult mitral valve orifice cross-sectional area is 4-6 cm2. When reduced to 2 cm2, hemodynamically significant MS occurs. At 1 cm2, obstruction to blood flow into the LV becomes critical because a left atrial mean pressure of 25 mm Hg is necessary to maintain normal cardiac output. Elevated left atrial pressure is transmitted to the pulmonary veins and pulmonary capillaries. Congested bronchial veins encroach on small bronchioles and cause subsequent increase in airway resistance. In addition, elevated hydrostatic pressure in the capillaries forces fluid into the alveoli and interstitial space, producing pulmonary congestion.

As a compensating mechanism, pulmonary vasoconstriction develops, causing pulmonary hypertension. At this stage, the right ventricle (RV) faces an increased afterload, leading to RV hypertrophy. Over time, fixed pulmonary arterial hypertension may develop from medial hypertrophy and intimal thickening of the pulmonary arterioles. RV myocardial dysfunction may develop, resulting in tricuspid valve regurgitation. Severe MS results in decreased cardiac output. If reduction in cardiac output is critical, end organ failure with shock, metabolic acidosis, and renal and/or hepatic insufficiency can occur. In addition, RV failure provokes systemic venous congestion with development of hepatomegaly, ascites, and pedal edema.

Hemodynamic changes in severe mitral valve stenosi Hemodynamic changes in severe mitral valve stenosis (MS). MS causes an obstruction (in diastole) to blood flow from the left atrium (LA) to the left ventricle (LV). Increased LA pressures are transmitted retrograde to pulmonary veins and pulmonary capillaries, resulting in capillary leak with subsequent development of pulmonary edema. To overcome pulmonary edema, the arterioles constrict, increasing pulmonary pressures. Over time, capillaries develop intimal thickening, causing fixed (permanent) pulmonary hypertension. The right ventricle (RV) hypertrophies to generate enough pressure to overcome the increased afterload. Eventually, the RV fails, which manifests as hepatomegaly and/or ascites, edema of the extremities, and cardiomegaly on radiography.

Natural history

Patients may remain asymptomatic for many years as long as the MS is mild and not accompanied by more than mild MR. These patients, of course, are susceptible to further damage to the mitral valve with repeated group A streptococcal pharyngitis. For this reason, ongoing antibiotic prophylaxis is recommended.

By the second or third decade of life, calcium deposits further constrict the effective mitral orifice of the already damaged mitral valve. Once the effective valvular orifice decreases significantly, symptoms occur.

In developing countries, rheumatic MS manifests 10-30 years after the initial rheumatic insult to the mitral valve. In developed countries, this latent period may be as long as 50 years.

Prognosis

Untreated acquired MS due to rheumatic heart disease follows a slowly progressive course, with the patient remaining asymptomatic for years before dyspnea or sudden deterioration from atrial fibrillation ensues. The overall 10-year survival rate of untreated patients who have acquired MS is 50-60%, but the 10-year survival rate reaches 80% if the patient is asymptomatic. Once symptoms develop, prognosis worsens significantly. If the patient presents with dyspnea, the 1-year survival rate is less than 15%.

After percutaneous balloon valvotomy or surgical commissurotomy, the 5- to 7-year survival rate is 50-90%.

After surgical commissurotomy, the reoperation rate is 5-7% and the 5-year complication-free survival rate 80-90%.

Mitral valve replacement entails a 5% mortality risk in young, healthy patients.

Morbidity/mortality

If symptoms are absent or minimal, the overall 10-year survival rate of untreated patients with MS is 80%. Once symptoms develop, the mortality risk and disease progression increase substantially. In an unselected group of patients with MS of varying severity, 60% were alive after 10 years.

A significant risk of arterial embolization is observed in patients with atrial fibrillation. Atrial fibrillation has been attributed to left atrial distension, which creates conduction delay in the posterior left atrium on a line that runs vertically between the pulmonary veins.[2] Increased inflammation is also thought to provoke atrial arrhythmias in these patients because patients with MS and atrial arrhythmias were found to have higher plasma levels of C-reactive protein.[3, 4]

If congestive heart failure (CHF) develops, the prognosis is grim, with a 10-year survival rate of 15%.

Complications

If MS is left untreated, the following complications may develop:

  • Pulmonary edema

  • RV failure

  • Renal insufficiency (caused by low cardiac output)

  • Progression to pulmonary hypertension

  • Atrial arrhythmias such as fibrillation or flutter

  • Thromboembolic complications

  • Dysphagia from compression of esophagus by the enlarged left atrium

Complications of medical treatment include the following:

  • Diuretics may provoke dehydration (decreased preload) with subsequent compromise in cardiac output. Because of electrolyte derangements, these drugs may also predispose patients to arrhythmias when administered with digoxin or class I or III antiarrhythmics.

  • Antiarrhythmic medications or electrolyte derangements precipitate fatal arrhythmias.

  • Warfarin may cause hemorrhagic complications.

Complications of surgery include the following:

  • Mitral commissurotomy may cause significant MR that may necessitate mitral valve replacement.

  • Complications of mitral valve replacement include valve thrombosis, valve dehiscence, infective endocarditis, valve malfunction, embolic events, and anticoagulation-related complications.

Percutaneous balloon valvuloplasty may result in significant MR (especially if the mitral valve is already calcified). Approximately 3% of patients require mitral valve replacement after balloon valvuloplasty. Fatality occurs in 1-2% of patients. Perforation of the ventricle occurs in 0.5-4%. Embolic events occur in 1-3%. Myocardial infarction occurs in 0.3-0.5% of patients.

Race

Genetic predisposition plays a significant role in occurrence of rheumatic fever after group A streptococcal infection. Family studies suggest that susceptibility to the disease involves a single recessive gene.

Sex

Rheumatic fever equally affects both sexes. However, in those who acquire rheumatic heart disease, MS is more common in women. Reasons for this are unknown.

A recent study found that, although MS is more frequent in women, mitral regurgitation is equally frequent in both sexes.[5]

Age

Rheumatic fever is a disease of childhood, its incidence parallels that of streptococcal pharyngitis. MS usually arises in persons older than 15-20 years because the disease progresses to that stage over many years. This time interval is significantly shorter in developing countries.

Epidemiology

Frequency

United States

Acquired MS is exceedingly rare in the pediatric population in the United States. Acquired MS secondary to rheumatic fever remains the most common form of MS that occurs in adulthood. Current estimates indicate that the prevalence of rheumatic fever in the United States is less than 1 case per 100,000 people. A steady decline has been observed in the incidence of rheumatic fever and, thus, in acquired MS.

International

In some developing countries, such as India, the prevalence of rheumatic fever is 100-150 cases per 100,000 people.[1] Following development of rheumatic heart disease, evidence of MS may develop as early as the teenage years, presumably because of a more aggressive initial attack and/or recurrent bouts of rheumatic fever (consequences of suboptimal or absent antibiotic prophylaxis). In some developing countries, the prevalence of rheumatic heart disease in children is 5-15 cases per 1000 people.

 

Presentation

History

Patients with mild mitral stenosis (MS) may deny all symptoms. They may provide a history consistent with acute rheumatic fever; however, in a given patient, an inverse relationship between the severity of rheumatic heart disease and the severity of rheumatic arthritis is often observed.

The most prominent symptom of severe MS is dyspnea. This results from pulmonary congestion. Patients with severe MS may also experience orthopnea as well as significant exercise limitation.

MS due to rheumatic heart disease rarely occurs in childhood in the United States. When it does occur, the history generally reveals the insidious onset of exercise limitation. These patients may present with certain signs.

Pulmonary congestion is evidenced by increasing severity of dyspnea (depending on the degree of MS), ranging from dyspnea only during exercise to paroxysmal nocturnal dyspnea, orthopnea, or even symptoms related to frank pulmonary edema.

Dyspnea may be precipitated or worsened by an increase in blood flow across the stenotic mitral valve (eg, pregnancy, exercise) or a reduction in diastolic filling time because of increased heart rate (eg, emotional stress, fever, respiratory infection, atrial fibrillation with rapid ventricular rate).

Signs of right heart failure, including peripheral edema and fatigue, may appear late.

Approximately 30-40% of patients with MS eventually develop atrial fibrillation. This rarely occurs in the pediatric age group. Atrial fibrillation may cause the following:

  • Loss of the atrial kick to the LV filling that may further diminish cardiac output

  • Thromboembolic events, occurring in 10-20% of patients with MS, approximately 75% of which cause stroke

  • Infective endocarditis, which should be suspected if embolization occurs during sinus rhythm

Hemoptysis may be caused by rupture of dilated bronchial veins, and pink frothy sputum may be a manifestation of pulmonary edema. Both are associated with endstage and severe MS.

Chest pain, possibly related to RV hypertension, occurs in approximately 15% of patients with MS.

Rarely, dysphagia may occur from compression of the esophagus by an enlarged left atrium. Hoarseness may occur if the enlarged left atrium impinges on the recurrent laryngeal nerve.

Physical

Physical examination findings vary according to the severity of MS.

Mild-to-moderate MS signs include the following:

  • Normal peripheral pulses and good perfusion

  • Loud S1 because of abrupt closure of a stenotic, but still pliable, mitral valve

  • Long A2 to opening snap interval: In mild MS, left atrial pressure is mildly increased; as a result, the mitral valve opens at a more normal interval after closure of the aortic valve (A2).

  • Diastolic murmur: The diastolic murmur of MS begins at the time of mitral valve opening and accentuates following atrial contraction (presystolic accentuation) as long as the patient is in sinus rhythm. The murmur is low frequency and rumbling in quality. In mild MS, the mid diastolic murmur may be difficult to hear. As MS becomes more severe, murmur duration increases, and, to some extent, intensity also increases.

  • No S3

  • Pulmonic component of S2: The pulmonic component of the second heart sound increases in intensity in direct proportion to elevation of left atrial (and, consequently, pulmonary artery) pressure. Similarly, the A2 -P2 splitting interval narrows as pulmonary artery pressure increases.

Severe MS signs include the following:

  • Diminished peripheral perfusion and pulses because of decreased cardiac output

  • Palpation of an RV impulse (enlarged RV) because of pulmonary hypertension

  • Soft S1 because of decreased mobility of the mitral leaflets as they become more thickened and/or calcified: Decreased cardiac output with severe stenosis also decreases the intensity of the S1, particularly with a faster heart rate.

  • Shorter A2 to opening snap interval: As left atrial pressure increases, the mitral valve opens earlier in relation to aortic valve closure (S2).

  • Diastolic rumble: A long, low-frequency diastolic rumble with presystolic accentuation is best heard at the apex. Murmur intensity decreases as cardiac output decreases.

  • Increased intensity of pulmonic component of S2 (P2) secondary to pulmonary hypertension

  • RV S3 or RV S4: RV S3 or RV S4 may occur; however, an RV S3 is rare in the presence of tricuspid valve regurgitation.

  • Systolic murmur: A systolic murmur of tricuspid regurgitation may occur as right ventricular function deteriorates. This murmur is best heard at the lower left sternal edge. It accentuates with inspiration.

  • Diastolic murmur: A high-frequency early diastolic murmur of pulmonic valve regurgitation may be heard immediately following an accentuated P2. Eponymously called the Graham Steell murmur, this finding reflects severe pulmonary hypertension.

Causes

In order for MS to develop from acute rheumatic fever, two conditions are required: infection with group A streptococcus and genetic susceptibility to develop valvular disease.

Epidemiology

Acute rheumatic fever is an immunologic disease that occurs in 0.3-3% of patients as a complication of group A streptococcal infection of the pharynx. It is very rarely observed after group A streptococcal infection of the skin.

Inheritance

A distinct genetic susceptibility to rheumatic fever is observed, with studies suggesting a single recessive gene. Other studies identified an allotypic marker on B lymphocytes, present in almost all patients with rheumatic fever but in only a small proportion of healthy controls. Investigations also revealed a significantly higher percentage of certain human leukocyte antigens (HLAs) in patients with rheumatic fever than in controls.

Risk factors

Family history of rheumatic fever is a risk factor and is consistent with genetic factors. Poverty, poor hygiene, and medical deprivation are predisposing factors for rheumatic fever, probably because they identify a population less likely to obtain proper treatment of streptococcal pharyngitis.

Acquired MS

Acquired MS results from long-term damage to the mitral valve and its supporting structures.

In rheumatic heart disease, autoimmune responses occur secondary to beta-hemolytic streptococci group A antigens. Damage to the heart is postulated to result from antiheart antibodies (eg, gamma globulins, complement C3). An initial pancarditis, which involves the pericardium, epicardium, myocardium, and endocardium, may result in long-term changes with damage along the free edges of a heart valve with deposition of platelets that result in inflammation plus subsequent fibrosis, and, finally, contracture of the valve leaflets. If inflammation is severe, cusps are damaged, and valvar insufficiency ensues. The mitral and aortic valves are the most commonly affected.

Poststreptococcal reactive arthritis (PSRA) is an arthritic condition that does not fulfill the Jones criteria for acute rheumatic fever. Therefore, patients have elevated acute phase reactants and serologic evidence of recent group A streptococcal infection; however, arthritis is additive rather than migratory, responds poorly to salicylates and nonsteroidals, and persists for a mean of 2 months. PSRA is associated with the HLA-DRB1*01.[6] As many as 6% of patients with PSRA develop mitral valve disease.

Systemic lupus erythematosus may induce pericarditis, myocarditis, and endocarditis (ie, Libman-Sacks endocarditis), which consists of verrucous vegetations on the valves composed of proliferating and degenerating cells, fibrin, and occasional hematoxylin body deposits. The most commonly affected valve is the mitral valve, but these lesions rarely cause either valvar insufficiency or stenosis.[7]

Amyloidosis, which is rare in childhood, is secondary to an underlying inflammatory process. Extracellular deposits of insoluble proteins (amyloid) in the myocardium, pericardium, and conducting tissue produce a restrictive or hypertrophic cardiomyopathy. When amyloid deposits in the valves, valvar insufficiency and/or stenosis can ensue.

Postsurgical acquired MS, such as MS occurring after mitral valve annuloplasty for severe mitral valve regurgitation, is caused by fibrosis along the annulus. These patients may require mitral valve replacement with a prosthetic mitral valve if the MS is severe enough to cause symptoms (eg, pulmonary edema). Improper repair of the cleft mitral valve in an endocardial cushion defect can also result in MS.

Post-procedure acquired MS due to occlusion of flow across the valve following device placement for mitral paravalvular leak has been described.[8]

 

DDx

Diagnostic Considerations

Important considerations

It is important for clinicians to diagnose the primary problem, recognize worsening symptoms, and recommend prophylaxis to prevent recurrent rheumatic heart disease.

Special concerns

Pregnancy

Acquired mitral stenosis (MS), the most common valvular disease in pregnant women in developing countries, has begun to appear in the United States as a result of immigration.

During pregnancy a 50% increase in plasma volume and a 25% increase in erythrocyte volume occur. Cardiac output increases by 40%, and heart rate also increases; therefore, as transmitral flow increases and diastolic time decreases, mean pulmonary artery pressure augments by approximately 50%. It often manifests for the first time during pregnancy with orthopnea, paroxysmal nocturnal dyspnea, pulmonary edema, and hemoptysis. Finding deterioration by 1-2 New York Health Association (NYHA) classes in these patients is not unusual.[9]

Asymptomatic or minimally symptomatic patients who usually have mitral orifice areas larger than 1.5 cm2 may only require close observation. However, patients with smaller mitral orifice areas who are severely symptomatic may require balloon valvuloplasty or surgical commissurotomy before delivery. Balloon valvuloplasty of MS has a very low complication rate in experienced centers. Pregnancy is contraindicated in women with severe MS, and preconception counseling must be offered to these patients because of the high likelihood of a bad outcome.

Pregnant women requiring anticoagulation for a prosthetic mechanical mitral valve should receive heparin. Warfarin should probably be avoided, especially during the first and third trimesters.

In the event of atrial fibrillation, beta-blockers may be used. Cardioversion can be administered if necessary because it has been proven safe during pregnancy. Echocardiography must be accomplished prior to cardioversion in order to evaluate the left atrium and its appendage for thrombi.

Vaginal delivery is the recommended method in women with NYHA class I, and cesarean delivery is seldom indicated. Cesarean delivery or uncomplicated abdominal delivery is not an indication for antibiotic prophylaxis.

Lutembacher syndrome

Lutembacher syndrome is a rare clinical entity that consists of the fortuitous association of a secundum atrial septal defect (ASD) with rheumatic MS.

Because of a stenotic mitral valve, pressures in the left atrium are elevated. Because of the ASD, blood shunts left to right. This produces pulmonary overcirculation with hepatic congestion and low cardiac output.

Differential Diagnoses

 

Workup

Laboratory Studies

Rheumatic heart disease

Laboratory studies are nonspecific, unless the patient is experiencing an acute attack of recurrent rheumatic fever, in which case, C-reactive protein, sedimentation rate, and antistreptolysin O (ASLO) antibodies are evident

Chronic rheumatic mitral valve disease

Persistence of elevated levels of antibody to the streptococcal group A carbohydrate occur in most patients with chronic rheumatic mitral valve disease.

Systemic lupus erythematosus

Obtain studies for evaluation of antinuclear antibodies, antibodies to double stranded DNA, and lupus erythematosus (LE) cells.

Amyloidosis

Assess for amyloid deposits in affected tissues.

Electrocardiography

ECG findings are often within reference ranges in patients with mild MS.

In those with moderate-to-severe MS, ECG reveals left atrial enlargement, right ventricular hypertrophy, and, often, right atrial enlargement. It also reveals atrial dysrhythmia. A fragmented QRS (RSR', R or S wave notching in 2 contiguous leads) has been described in patients who have severe MS, lower ejection fraction, and increased pulmonary artery pressure.[10]

Histologic Findings

Cardiac involvement in rheumatic fever is characterized by inflammation of the endocardium and myocardium. Histologic changes are not observed during the early stage of myocarditis but become evident at later stages of the inflammatory process. The changes include tissue edema and a cellular infiltrate consisting of lymphocytes and plasma cells but few polymorphonuclear white blood cells.

Endocardial inflammation of the mitral valve produces essentially the same histologic changes observed in myocarditis.

Chest Radiography

Findings on chest radiographs may include the following:

  • Left atrial enlargement

  • Pulmonic trunk and right ventricular and right atrial enlargement

  • Pulmonary venous congestion that results in redistribution of pulmonary blood flow with greater flow to the upper lobes and interstitial edema manifested by Kerley B lines

Echocardiography

Transthoracic and transesophageal echocardiography are the most important diagnostic tools for evaluating patients with mitral stenosis (MS). Transesophageal echocardiography is recommended when transthoracic examination is incomplete, especially if left atrial thrombus is suspected. It is also used in the operating room and catheterization laboratory to assess the effectiveness of intervention.

Echocardiography provides the following:

  • Direct anatomic data is provided, including visualization of valve leaflet morphology and motility and measurement of valve orifice dimensions, as well as the degree of left atrial dilation.

  • Hemodynamic and physiologic data are provided, including the pressure gradient across the stenotic mitral valve, the presence and severity of mitral regurgitation, and the degree of pulmonary hypertension.

  • Spontaneous echo contrast is common in patients with MS, and its presence in the left atrium is associated with a higher risk of thromboembolism. One study postulated that platelet activation via increased sympathetic activity is responsible for this phenomenon.[11]

Magnetic Resonance Imaging and Computed Tomography Scanning

MRI is infrequently used; however, experience with this imaging modality is much less than with echocardiography.[12]

Multislice CT scanning has been described as a new modality to assess the mitral valve area in patients with MS.[12, 13]

Cardiac Catheterization

Cardiac catheterization can be used to obtain direct measurement of the pressure gradient across the mitral valve as well as pulmonary artery pressure and pulmonary vascular resistance.

Note the following:

  • The mitral valve area can be calculated using the Gorlin formula.

  • Currently, the diagnosis and hemodynamic assessment of patients with MS are performed noninvasively with echocardiography.

  • Cardiac catheterization may be needed to supplement the information obtained noninvasively. More commonly, it is performed to accomplish percutaneous balloon valvuloplasty.

  • Possible complications of cardiac catheterization include tachyarrhythmias, bradyarrhythmias, and vascular occlusion. Balloon valvuloplasty may result in significant mitral regurgitation.

  • Postcatheterization complications include hemorrhage, pain, nausea and vomiting, and arterial or venous obstruction from thrombosis or spasm.

 

Treatment

Medical Care

Asymptomatic patients with mild mitral stenosis (MS) require yearly follow-up care to monitor for disease progression. Yearly evaluation should include physical examination, chest radiography, and echocardiography.

Critically ill inpatients or those unable to receive oral medications may be treated intravenously.

For the patient with signs or symptoms of CHF, diuretics may provide benefit.

Tachyarrhythmias, such as atrial flutter and atrial fibrillation, usually require medical treatment aimed at restoration and maintenance of sinus rhythm. If this is not possible, therapy may be aimed at decreasing ventricular response and maintaining an acceptable heart rate. Pharmacotherapy may include the following:

  • Digoxin, beta-blockers, and calcium channel blockers have all been used to slow atrioventricular (AV) node conduction and decrease ventricular rate response.

  • Antiarrhythmics from class I (eg, procainamide, flecainide, propafenone) and class III (eg, sotalol, amiodarone) have been used with variable success in converting to and maintaining sinus rhythm.

  • Thromboembolic complication from chronic atrial arrhythmia can be reduced with anticoagulation using warfarin.

Electrophysiologic ablation of atrial fibrillation or flutter circuits may be performed in the catheterization laboratory.

Surgical ablation via a Cox-Maze procedure during mitral valve repair or replacement has been shown to be an effective treatment for atrial fibrillation with freedom from atrial fibrillation recurrence of nearly 80% after 10 years.[14]

Percutaneous mitral balloon valvuloplasty for acquired MS was first described in 1984 and approved by the US Food and Drug Administration in 1994. Indications for this procedure are similar to those for surgery, including CHF unresponsive to medical management and in asymptomatic patients with a pulmonary artery (PA) systolic pressure of 50 mm Hg or greater at rest or greater than 60 mm Hg with exercise in the absence of a left atrial thrombus or moderate to severe MR.[15] In some centers, the procedure is successful in 80-90% of selected cases. The procedural mortality rate is 1-2%.

Hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins) have reportedly slowed the progression of rheumatic MS.[16, 17]

Consultations

Consult a cardiologist and a cardiothoracic surgeon.

Transfer

Transfer patients to an ICU when general status is unstable because of CHF with pulmonary edema or serious cardiac dysrhythmia.

Once medically stabilized, surgical or transcatheter intervention should be considered.

Diet and activity

Salt intake should be restricted and excessive fluid intake minimized to avoid exacerbating signs and symptoms of CHF.

Patients with more severe than mild MS should avoid strenuous exertion. Increased heart rate may result in decreased diastolic filling, thereby decreasing cardiac output. Coexistent atrial arrhythmias result in loss of atrial augmentation of LV filling and may further impair cardiac output.

Surgical Care

Surgical intervention is indicated in symptomatic (NYHA functional class III-IV) moderate or severe MS when percutaneous MV balloon valvuloplasty is unavailable or contraindicated because of left atrial thrombus despite anticoagulation or concomitant moderate to severe MR, or when valve morphology is unfavorable for valvotomy.[10, 18]

Mitral valvotomy

Commissurotomy consists of an incision of fused mitral valve commissures and shaving of thickened mitral valve leaflets. Fused chordae tendineae and papillary muscles can be divided to relieve subvalvular stenosis.

Supravalvular tissue contributing to the MS should be resected.

Combined valvuloplasty with prosthetic ring annuloplasty is also used with reportedly good results.[19]

Mitral valve replacement with mechanical valve or bioprosthesis

This procedure is reserved for patients in whom mitral valvotomy is considered unlikely to achieve a satisfactory result, such as in those with moderate to severe MR.

Mechanical mitral valve replacement is performed frequently in adolescents and adults in whom anticoagulation with warfarin (Coumadin) is not contraindicated. In older patients in whom warfarin therapy may be relatively contraindicated or in patients who have other contraindications to warfarin therapy, mitral valve replacement can be performed using a bioprosthesis, although these are less durable than mechanical prostheses.

Weigh the risk of warfarin therapy against that of bioprosthetic valve deterioration resulting in the need for reoperation. Warfarin is contraindicated during pregnancy.

Complications after mitral valve replacement include anticoagulation-related complications, valve thrombosis, valve dehiscence, infective endocarditis, valve malfunction, and embolic events.

Hemolytic anemia when mild-to-moderate paravalvular leakage is present predicts poor clinical outcome in patients who have undergone mitral valve replacement.[20]

 

Medication

Medication Summary

Medical therapy is directed at alleviating symptoms, treating rhythm abnormalities, and preventing thromboembolic complications.

Diuretics

Class Summary

These agents promote excretion of water and electrolytes by the kidneys. They decrease fluid overload and pulmonary congestion.

Furosemide (Lasix)

Acts by inhibiting absorption of sodium and chloride in proximal and distal tubules and in the loop of Henle, thereby promoting excretion of sodium chloride and water. Acts as a diuretic and antihypertensive.

Potassium-sparing diuretics

Class Summary

These agents are used to prevent potassium depletion induced by more potent loop diuretics (eg, furosemide).

Spironolactone (Aldactone)

Used to decrease edema resulting from excessive aldosterone excretion. Inhibits aldosterone-dependent sodium-potassium exchange site in the distal convoluted renal tubule, thereby retaining potassium and excreting sodium and water. Serves as a diuretic and antihypertensive agent.

Inotropic-antiarrhythmic agents

Class Summary

These agents are mainly used in mitral stenosis (MS) in atrial flutter or fibrillation because of its antiarrhythmic properties. Digoxin is not expected to improve overall cardiac function because, in MS patients, heart failure is from mechanical obstruction causing elevated left atrial pressure, with subsequent transmission to RV and, ultimately, failure. Theoretically, digoxin could aid in improving RV dysfunction.

Digoxin (Lanoxin)

Digitalis glycoside that inhibits sodium-potassium ATPase (enzyme that extrudes sodium and brings potassium into myocyte). Resulting increase in intracellular sodium stimulates sodium-calcium exchange, extruding sodium and bringing in calcium with consequent increase in myocyte contractility. Exerts vagomimetic action on sinus and AV nodes (slowing heart rate and conduction). Also decreases degree of activation of sympathetic nervous system and renin-angiotensin system, referred to as the deactivating effect. Therapeutic serum level range is 0.8-2 ng/mL.

Class II antiarrhythmic agents (beta-blockers)

Class Summary

These agents are used for atrial flutter or fibrillation. Beta-adrenergic receptor blocking agents are used as a second option when digoxin does not stop atrial flutter or fibrillation.

Propranolol (Inderal)

By blocking the beta-adrenergic receptor, these compounds blunt chronotropic, inotropic, and vasodilator responses of any beta-adrenergic stimulation. Beta-blockers lower ventricular rate; therefore, they are used in patients with atrial flutter or fibrillation.

Esmolol (Brevibloc)

Selective beta-1 (cardioselective)–adrenergic receptor blocking agent; may be used with class I antiarrhythmics if digoxin therapy does not abort atrial arrhythmia. Administer in patients needing prompt slowing of ventricular rate in response to atrial flutter or fibrillation and who are most likely to become hemodynamically unstable if left without treatment or in those waiting for the start of the therapeutic effects of digoxin (average, 10 h).

Has rapid onset and short duration of action. Administered IV to stop atrial arrhythmia; afterward, patient is placed on class I antiarrhythmics for maintenance.

Class IA antiarrhythmics

Class Summary

These agents are used to stop atrial fibrillation and convert it into sinus rhythm. They can also decrease myocardial excitability.

Procainamide (Pronestyl)

Increases effective refractory period by reducing conduction velocity of atrial fibers and, to a lesser extent, the ERP of His-Purkinje and ventricles. Thus, decreases myocardial excitability and may speed AV node conduction (vagolytic effect). Therapeutic serum level range is 4-10 mg/L.

Class IC antiarrhythmics

Class Summary

These agents are used after digoxin and/or beta-blockers that have not converted atrial arrhythmia.

Propafenone (Rythmol)

Class IC antiarrhythmic drug that exerts local anesthetic effects and has direct stabilizing action on myocardial cell membrane. Reduces upstroke velocity (phase 0) of action potential by reducing rapid inward current carried by sodium ions. Prolongs effective refractory period and reduces spontaneous automaticity. Prolongs AV node conduction and does not affect sinus node.

Class III antiarrhythmics

Class Summary

These agents decrease rate of sinus node and relax vascular smooth muscle, with concomitant reduction in peripheral vascular resistance (afterload). They may also exert a mild negative inotropic effect.

Amiodarone (Cordarone)

Prolongs duration of myocyte action potential, prolongs myocyte refractory period, and exerts alpha- and beta-adrenergic inhibition. Therapeutic serum level ranges from 0.5-2.5 mg/L.

Anticoagulants

Class Summary

These agents are used to prevent clot formation secondary to blood stasis because of an enlarged (left) atrium and (left) atrial fibrillation.

Warfarin (Coumadin)

Inhibits vitamin K–dependent clotting factors II, VII, IX, and X and anticoagulant proteins C and S. Anticoagulation effect occurs 24 h after drug administration, but peak effect may happen 72-96 h later. Antidotes are vitamin K and FFP.

 

Follow-up

Further Outpatient Care

Follow-up visits to the pediatrician and/or generalist are needed to monitor general health status.

Follow-up clinical visits to the pediatric cardiologist are needed to monitor antiarrhythmic drug levels and anticoagulation drug effectiveness by measuring prothrombin time (PT) and/or international normalized ratio (INR).

Serial echocardiography is indicated to monitor progression of mitral stenosis (MS). The frequency of these studies varies according to the patient's general health status and according to the cardiologist's criteria. Stress echocardiography may provide additional hemodynamic information.

Further Inpatient Care

Intravenous diuretics may be used in patients with severe or refractory symptoms.

Oxygen administration or endotracheal intubation and mechanical ventilation may be necessary in patients with respiratory compromise due to pulmonary edema.

Patients with unstable tachyarrhythmias should undergo direct current (DC) cardioversion. Medical cardioversion can be attempted in patients who are hemodynamically stable. Echocardiography must be accomplished prior to cardioversion in order to assess the left atrium and its appendage for thrombi.

Deterrence/Prevention

Antibiotics for endocarditis prophylaxis are required for patients with certain cardiac conditions, such as MS, before performing procedures that may cause bacteremia. For more information, see the American Heart Association's Webpage on infective endocarditis.

Patient Education

Counsel patients and their families should be counseled regarding the appearance and/or worsening of symptoms.

Patients must follow American Heart Association infective endocarditis prophylaxis guidelines, and they should refrain from strenuous exercise.

Women should avoid taking warfarin during pregnancy. If MS is more severe than mild, strenuous activity and excessive salt intake are also contraindicated during pregnancy.