Learning Outcome

1. Describe mitral valve stenosis
2. Identify the etiology of mitral valve stenosis and the most common cause
3. List nursing diagnosis related to mitral valve stenosis
4. Recognize risk factors associated with mitral valve stenosis
5. Explain assessment findings related to history and physical
6. Understand mitral valve evaluation methods

Introduction

Mitral stenosis (MS) is a form of valvular heart disease. Mitral stenosis is characterized by narrowing of the mitral valve orifice. Today, the most common cause of mitral stenosis is rheumatic fever, but the stenosis usually appears clinically relevant only after several decades.

Nursing Diagnosis

• Risk for inadequate perfusion related to fluid overload as evidenced by weight gain greater than 3 pounds daily.
• Anxiety
• Edema
• Dyspnea
• Palpitations
• Fatigue
• Anorexia
• Chest discomfort

Causes

The most common cause of mitral stenosis is rheumatic fever. Uncommon causes of mitral stenosis are calcification of the mitral valve leaflets and congenital heart disease. Other causes of mitral stenosis include infective endocarditis, mitral annular calcification, endomyocardial fibroelastosis, malignant carcinoid syndrome, systemic lupus erythematosus, Whipple disease, Fabry disease, and rheumatoid arthritis.

Risk Factors

The prevalence of rheumatic disease in developed countries is declining, with an estimated incidence of 1 in 100,000. The prevalence is higher in developing nations than in the United States. In Africa, for example, the prevalence is 35 cases per 100,000. 

Rheumatic mitral stenosis is more common in females. The onset is usually between the third and fourth decades of life.[1][2]

Assessment

Mitral stenosis presents 20 to 40 years after an episode of rheumatic fever. The most common symptoms are orthopnea and paroxysmal nocturnal dyspnea. Patients may have palpitations, chest pain, hemoptysis, thromboembolism when the left atrial volume is increased, ascites, edema, and hepatomegaly (if right-sided heart failure develops).

There is also an increase in symptoms of fatigue and weakness with exercise and pregnancy.

On auscultation, the first heart sound is usually loud and might be palpable due to increased force in the closing of the mitral valve.

The P2 (pulmonic) component of the second heart sound (S2) will be loud if severe pulmonary hypertension is due to mitral stenosis. 

An opening snap (OS) is an additional sound that may be heard after the A2 component of the second heart sound (S2). This is the forceful opening of the mitral valve when the pressure in the left atrium is greater than the pressure in the left ventricle.

A mid-diastolic rumbling murmur with presystolic accentuation is heard after the opening snap. This murmur is a low-pitched sound. It is best heard with the bell of the stethoscope at the apex. The murmur accentuates in the left lateral decubitus position and with isometric exercise.

Advanced mitral stenosis presents with signs of right-sided heart failure (jugular venous distension, parasternal heave, hepatomegaly, ascites) and/or pulmonary hypertension.

Other signs include atrial fibrillation, left parasternal heave (right ventricular hypertrophy due to pulmonary hypertension), and tapping the apical beat.

Evaluation

Mitral stenosis is evaluated using noninvasive and invasive measures. Noninvasive tests are the electrocardiogram (ECG), chest X-ray, echocardiogram, and exercise echocardiogram. An invasive test for mitral stenosis would include a cardiac catheterization.[3][4][5]

On the ECG, the P wave changes suggest left atrial enlargement. The presence of right axis deviation and right ventricular hypertrophy suggests severe pulmonary hypertension. ECG frequently detects atrial arrhythmias such as atrial fibrillation.

On the chest x-ray, the early stages of mitral stenosis findings are normal heart size, straightening of the left border of the cardiac silhouette, prominent main pulmonary arteries, dilatation of the upper pulmonary veins, and displacement of the esophagus by an enlarged left atrium. During the severe chronic stage of mitral stenosis, the chest x-ray will have enlargement of all the chambers, pulmonary arteries, and pulmonary veins.

An echocardiogram is useful for assessing mitral stenosis etiology, morphology, severity, and treatment intervention. The analysis of the morphology of the mitral valve apparatus includes leaflet mobility and flexibility, leaflet thickness, leaflet calcification, subvalvular fusion, and the appearance of commissures. The Wilkins score grades each of the components of the mitral apparatus from 1 to 4: leaflet mobility, thickness, calcification, and impairment of the subvalvular apparatus. The Padial score grades the leaflet thickening (each separately), the commissural calcification, and the subvalvular disease from 1 to 4. The Wilkins score of less than 8, a Padial score of less than 10, and less than moderate regurgitation have better outcomes.

An exercise echocardiogram is performed using an upright treadmill or supine bicycle with Doppler recording of transmitral and tricuspid valve velocities. This measures the transmitral gradient and pulmonary artery systolic pressure at rest and with exercise.

Cardiac catheterization is an invasive procedure. Cardiac catheterization should be performed for assessment of the severity of mitral stenosis when noninvasive tests are inconclusive or when there is a discrepancy between noninvasive tests and clinical findings regarding the severity of mitral stenosis (Class I, Level of Evidence C).

Classification of Severity of Mitral Valve Stenosis 

Mild

• Mean gradient (mmHg) less than 5
• Pulmonary artery systolic pressure (mmHg) less than 30
• Valve area (cm2) less than 1.5

Moderate

• Mean gradient (mmHg) 5 to 10
• Pulmonary artery systolic pressure (mmHg) 30 to 50
• Valve area (cm2) 1.0 to 1.5

Severe

• Mean gradient (mmHg) less than 10
• Pulmonary artery systolic pressure (mmHg) greater than 50          
• Valve area (cm2) less than 1.0                                                  

Mitral Valve Anatomy According to the Wilkins Score

Grade 1

• Mobility: Highly mobile valve with only leaflet tips restricted
• Thickening: Leaflet near normal in thickness (4 mm to 5 mm)
• Calcification: A single area of increased echo brightness
• Subvalvular Thickening: Minimal thickening just below the mitral leaflets

Grade 2

• Mobility: Leaflet mid to base portions have normal mobility
• Thickening: Mid leaflets normal, considerable thickening of margins (5 to 8 mm)
• Calcification: Scattered areas of brightness confirmed to leaflet margins
• Subvalvular Thickening: Thickening of chordal structures extending to one of the chordal lengths

Grade 3

• Mobility: Valve continues to move forward in diastole, mainly from the base
• Thickening: Thickening extending through the entire leaflet (5 mm to 8 mm)
• Calcification: Brightness extending into the mid portions of the leaflets
• Subvalvular Thickening: Thickening extended to the distal third of the chords

Grade 4:

• Mobility: No or minimal forward movement of the leaflets in diastole
• Thickening: Considerable thickening of all leaflet tissue (more than 8 mm to 10 mm)
• Calcification: Extensive brightness throughout much of the leaflet tissue
• Subvalvular Thickening: Extensive thickening and shortening of all chordal structures extending down to the papillary muscles. 

Medical Management

Treatment for mitral stenosis involves medical therapy, percutaneous mitral valvuloplasty, and surgical therapy. Currently, no medical therapy can relieve a fixed obstruction of the mitral valve. Medical therapy is focused on preventing endocarditis, decreasing new cases of rheumatic fever, improving symptoms, and decreasing the thromboembolic risk.[6][7][8]

Endocarditis prophylaxis should only be given to high-risk patients before dental procedures involving gingival tissue manipulation or perforation of the oral mucosa. High-risk patients are those patients with a prosthetic heart valve or prosthetic material used for valve repair, previous history of infective endocarditis, and cardiac valvuloplasty.

Rheumatic fever prophylaxis with Benzathine penicillin is the primary prevention treatment in patients with streptococcal pharyngitis.

If the rhythm is normal sinus, medical therapy is used to improve symptoms. Diuretics are utilized to help relieve congestion. Beta-blockers and/or calcium channel blockers help with exertional symptoms associated with elevated heart rate.

If the rhythm is atrial fibrillation, the first step is to control the rate using AV node blocking agents such as beta-blockers, calcium channel blockers, and/or digitalis. In an unstable patient, perform direct current cardioversion. If one cannot convert atrial fibrillation to normal sinus rhythm, then the primary goal is rate control. In a stable patient, restoring normal sinus rhythm is preferred over rate control to improve functional capacity and quality of life.

Anticoagulation prevents thromboembolic events. Anticoagulation is indicated in patients with mitral stenosis and atrial fibrillation (paroxysmal, persistent, or permanent), previous embolic events, and the presence of left atrial thrombus. At present, Warfarin is the anticoagulation of choice. Aspirin or other antiplatelet drugs are not approved to decrease thromboembolic risk in mitral stenosis. Warfarin should be monitored using the international normalized ratio (INR) to target 2.5.

Percutaneous mitral balloon valvuloplasty (PMBV) is an invasive procedure to manage mitral stenosis. PMBV improves symptoms by increasing mitral valve area and reducing mitral valve gradient. PMBV is indicated in symptomatic patients (New York Heart Association functional class greater than II) or asymptomatic patients with pulmonary hypertension with moderate or severe stenosis and favorable valve morphology in the absence of left atrial thrombus or moderate to severe mitral regurgitation.

Mitral valve replacement surgery is indicated in patients with symptomatic moderate or severe mitral stenosis when percutaneous mitral balloon valvuloplasty is contraindicated or unfavorable valve morphology (Class I, Level of Evidence B).

Nursing Management

• Monitor vital signs
• Universal precaution for infection control to prevent endocarditis and decrease rheumatic fever
• Symptom management
• Monitor signs and symptoms of deep vein thrombosis
• Elevate legs above the heart
• Monitor fluid intake to avoid fluid overload
• Assess ECG
• Monitor INR
• Listen to the lungs as pulmonary edema is common
• Listen to the heart-MS presents with a loud S1
• Encourage diet (Failure to thrive is common)
• Educate patients on the disease and surgery

When To Seek Help

• Weight gain greater than 3 pounds daily
• Shortness of breath
• Chest pain

Outcome Identification

Prior to the era of open-heart surgery, the prognosis for most patients with mitral stenosis was poor. In the age of mitral valve replacement, the prognosis is excellent. Survival is significantly better for patients undergoing an open mitral valve replacement compared to a commissurotomy. Today, there is an 80% survival at ten years, but in patients who have developed pulmonary hypertension, the survival is less than three years. Other complications that may result in high morbidity include stroke and persistent atrial fibrillation.[9][10] [Level 5]

Monitoring

• Blood pressure
• Temperature
• Respiration
• CBC with differential
• CMP
• Fluid and electrolytes
• INR
• ECG to assess the presence of atrial arrhythmias

Coordination of Care

Once the diagnosis of mitral stenosis is made, the patient should be educated about the need for surgery. Those who remain asymptomatic will need annual exams, including echocardiograms. Patients with palpitations may require a Holter monitor to confirm the presence of atrial arrhythmias. Many of these patients will need anticoagulation with warfarin. Hence, the pharmacist should ensure that monthly blood work is done to ensure therapeutic anticoagulation. A dietary consult is often important as failure to thrive is common. Finally, the patient should be educated on the type of prosthetic valves available and which may be best suited for them. Finally, the primary care provider, pharmacist, and nurses should discuss with the patient the possibility of developing an infection of the valve and the need for prophylaxis when undergoing any type of invasive procedure.[11][12] [Level 5]

Health Teaching and Health Promotion

• Educate patient on the disease process
• Discuss with the patient the importance of immunization
• Educate patients on prophylaxis to prevent endocarditis during dental procedures.
• Discuss plan of care with patient 

Risk Management

Mitral stenosis is a relatively common disorder, which, if left untreated, is associated with high morbidity and mortality. Mitral stenosis rates had decreased in the US 4 decades ago, but with the mass migration of individuals from other countries, a resurgence of cases has been observed. The number one cause for most cases of mitral stenosis is rheumatic fever. The key is to prevent the valvular disorder by ensuring that patients with strep throat are adequately treated. Because of the high morbidity of the disorder, the condition is best managed by an interprofessional team.

Once the diagnosis of mitral stenosis is made, the patient should be educated about the need for surgery. Those who remain asymptomatic will need annual exams, including echocardiograms. Patients with palpitations may require a Holter monitor to confirm the presence of atrial arrhythmias. Many of these patients will need anticoagulation with warfarin. Hence, the pharmacist should ensure that monthly blood work is done to ensure therapeutic anticoagulation. A dietary consult is often important as failure to thrive is common. A cardiology nurse should monitor the patient for symptoms as they will require surgery. The type of prosthetic valve used depends on patient factors.

Cardiac surgery nurses should educate the patient on the type of prosthetic valves available and which may be best suited for them. Finally, the primary care provider, pharmacist, and nurse should discuss with the patient the possibility of developing an infection of the valve and the need for prophylaxis when undergoing any type of invasive procedure. Because atrial fibrillation is a persistent problem, anticoagulation will be required in most patients. Hence, close monitoring of the INR by a dedicated nurse is necessary.[11][12] [Level 5]

Discharge Planning

• Medication reconciliation
• Follow appointment

Evidence-Based Issues

Review facility protocol on how to manage a patient with mitral stenosis.

Pearls and Other issues

Pregnancy during mitral stenosis will increase the patient’s symptoms by one New York Heart Association class. Medical therapy is attempted first to improve symptoms. If symptoms do not improve with medical treatment, refer the patient for percutaneous mitral balloon valvuloplasty.