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Subject: Mitral Stenosis
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The mitral valve apparatus is made up of anterior and posterior leaflets which are attached to the anterolateral and posteromedial papillary muscles via the chordae.
Mitral stenosis (MS) is a narrowing of the valve area causing obstruction of the left ventricular inflow, resulting in increased left atrial pressures and consequent elevation of pulmonary venous and atrial pressures.
Normal valve orifice 4 to 6 cm2; symptoms typically seen when orifice is ≪2.5 cm21.
Staging of the disease is used to guide appropriate treatment regimen. Stages vary from A (with risk factors), B (hemodynamic obstruction), C (severe but no symptoms), to D (symptomatic) 1.
The most common etiology for MS is rheumatic heart disease (RHD), and MS is the most common valvular disease secondary to RHD.
Other etiologies will be discussed below.
Globally, the prevalence of RHD is 15.6 million every year. Approximately 282,500 new cases are reported and 233,000 deaths have been attributed to RHD 2.
Predominant age: Symptoms primarily occur in 3rd to 4th decades; predominant sex: female > male (2:3)
Narrowing of the valve orifice leads to obstruction of blood flow between LA and LV. This impairs LV filling during diastole and causes increased LA pressure. Increased LA pressure is transmitted passively (“back pressure”) to the pulmonary circulation causing pulmonary hypertension and pulmonary congestion over time.
Chronic LA pressure overload results in atrial dilation and fibrosis and may cause Afib.
Rheumatic fever: most common etiology (see “Risk Factors”)
Aging (extension of mitral annular calcification)
Rare causes: congenital (associated with mucopolysaccharidoses), autoimmune: systemic lupus erythematosus (SLE); rheumatoid arthritis; malignant carcinoid; Whipple disease; methysergide therapy; and other acquired pathologies such as LA myxoma, LA thrombus, endomyocardial fibrosis
Rheumatic fever is the greatest risk factor.
Aging (increasing valvular calcification)
Chest irradiation (increasing tissue fibrosis)
Prompt recognition and treatment of GAS infection; recognition of cardinal signs and symptoms of acute rheumatic fever via Jones criteria
Ultrasound-based screening has been shown to increase diagnosis of RHD in asymptomatic patients residing in areas of high prevalence.
Afib (30-40% of symptomatic patients)
Associated valve lesions due to chronic inflammation (aortic stenosis, aortic insufficiency)
Pulmonary HTN and right heart failure
Systemic embolism, stroke, pulmonary embolism (10%)
Infection, including infectious endocarditis (1-5%)
Chronic rheumatic myocarditis
History of rheumatic fever
Severity depends on valve area; most early cases will be asymptomatic.
Mean age of symptom onset in rheumatic valvular disease is in the late 30s to 40s. Latent period 20 to 40 years after infection. Rapid progression can be seen in some high prevalence areas.
Presenting features usually include dyspnea on exertion, decreased exercise tolerance, chest pain, embolic events, palpitations, hoarseness, hemoptysis, fatigue, paroxysmal nocturnal dyspnea, Afib, and embolic events.
In advanced disease, symptoms of pulmonary HTN and right heart failure predominate: jugular venous distention, hepatomegaly, ascites, and peripheral edema
Other presentations: hemoptysis (due to increased collateralization between pulmonary and bronchial circulation causing intraparenchymal hemorrhage), hoarseness (compression of recurrent laryngeal nerve by enlarged pulmonary artery or LA), dysphagia (compression of bronchi), chronic cough (due to LA compressing the bronchi) and infective endocarditis. Not infrequently, symptoms are first noted in pregnancy.
Elevated jugular venous pressure, left parasternal heave. Apical impulse may be displaced, diastolic thrill in the left lateral decubitus position
If pulmonary HTN is present, increased P2, highpitched decrescendo diastolic murmur of pulmonic insufficiency is heard (Graham Steell murmur); may have signs of right heart failure
May also find associated aortic or tricuspid murmurs due to involvement from RHD
Chest radiograph 4,5[C]
Transthoracic echo (TTE) recommended in all patients with signs and symptoms of MS 1[B]
TEE should be performed if TTE images are nondiagnostic or if being considered for a percutaneous mitral balloon commissurotomy (PMBC) to exclude thrombus in left atrium and evaluate severity of MR 1[B].
Exercise stress testing can also be considered in patients with MS who have a discrepancy in their symptoms and signs and resting Echo findings 1[C].
Cardiac catheterization indications 1,5[C]
If valve area >1.5 cm2 and mean pressure gradient ≪5 mm Hg, clinical f/u in 3 to 5 years is recommended.
Otherwise, f/u is usually symptom based. Symptomatic patients with severe MS need further evaluation for interventional/surgical treatment.
Holter monitor placement in order to r/o paroxysmal Afib.
Exercise testing is recommended for those with clinical discrepancy.
Wilkin's score evaluates valvular anatomy from a TTE in order to see if patient is a candidate for surgery.
Rheumatic fever-induced pathologic changes: leaflet thickening, leaflet calcification, commissural fusion, chordal shortening
MV area defined 1
Treatment is dependent on severity of stenosis and symptoms.
Patients who have a valvular area >1.5 cm2 and no symptoms can be managed medically.
MS is generally progressive, and medical therapy only delays the need for definitive therapy. It entails (i) treatment to prevent recurrence of rheumatic fever, (ii) treatments aimed at improving dyspnea and exercise tolerance, (iii) controlling the ventricular rate whether in sinus rhythm or Afib, (iv) and anticoagulation for prevention of thromboembolic events.
Antibiotic prophylaxis against rheumatic fever and/or carditis is recommended for patients with history of rheumatic fever 1[C].
Secondary prophylaxis is dependent on many factors: number of previous attacks, time since previous infection, risk for getting GAS, age of patient, and absence or presence of cardiac involvement 6.
Antibiotic prophylaxis against infective endocarditis is not routinely recommended, unless there are other indications 1[B].
Diuretics for congestive symptoms 1[A]
β-Blockers or nondihydropyridine calcium channel blockers used for controlling heart rate both in SR and AF to allow adequate diastolic filling and decrease LA diastolic pressure tachycardia or exertional symptoms 1
Consider cardioversion, especially in patients with mild MS and recent dx of Afib (≪6 months).
Use of anticoagulation 1[B]
Warfarin is the only accepted modality for anticoagulation in patients with rheumatic mitral valve disease (international normalized ratio) range 2 to 3.
Heparin in the acute Afib setting
The new oral anticoagulants (factor Xa inhibitor and direct thrombin inhibitor) are not approved for use in Afib that is secondary to MS.
Surgical techniques include balloon valvotomy, open mitral commissurotomy, or closed mitral commissurotomy and mitral valve replacement.
Patients with severe MS and symptoms consistent with NYHA class III to IV are candidates for surgery.
Any patient with a valve area >1.5 cm2, LA thrombus, moderate MR, severe bicommissural calcifications, severe aortic valve disease, moderate TR or TS, concomitant coronary artery disease are not candidates for PMBC.
PMBC is recommended for those with severe MS symptoms and favorable valve morphology 1[A], in asymptomatic patient with very severe MS and favorable valve anatomy in the absence of symptoms 1[C], and in patients with suboptimal valvular anatomy, with a high risk for surgery 1[C].
Balloon valvotomy: symptomatic patients with NYHA class II, III, or IV symptoms with valves that look favorable and with favorable comorbidities 1[A]
MV surgery: when MS is severe with severe symptoms (NYHA class III to IV) who are not high-risk surgical candidates and balloon valvotomy is contra-indicated or failed PMBC 1[B]
Consider patient age, bleeding risk, and other comorbidities prior to deciding if patient should have a prosthetic versus mechanical valve.
Volume expansion during pregnancy can exacerbate heart failure symptoms. Patients with known severe MS, prepregnancy discussions should be pursued with a cardiologist.
Pregnant patients can safely use β-blockers. Despite some concerns of teratogenic affects with diuretics, furosemide has been used in symptomatic MS patients during pregnancy with minimal adverse effects.
Coumadin is considered relatively safe in the 2nd and 3rd trimesters if anticoagulation is required. However, unfractionated heparin is preferred prior to labor and delivery.
Counsel patients with MS that is usually slowly progressive but can have sudden onset of Afib, which could become rapidly fatal. Call 911 for marked worsening of symptoms.
Echocardiographic surveillance in asymptomatic patients in any degree of MS: very severe (≪1.0 cm2) MS: yearly, severe (≤1.5 cm2) MS: every 1 to 2 years, mild or moderate MS: every 3 to 5 years
Follow-up will depend on the severity of the MS and the patient's symptoms.
Asymptomatic latent period after rheumatic fever for 10 to 30 years. 10-year survival for asymptomatic or minimally symptomatic patients is 80%.
10-year survival after onset of debilitating symptoms is only 0-15%.
Mean survival with significant pulmonary HTN is ≪3 years.
Commissurotomy is an effective means of reducing stenosis but is not curative. Restenosis sometimes occurs and can be early (≪5 years) or late (>20 years).
I05.0 Rheumatic mitral stenosis
I05.8 Other rheumatic mitral valve diseases
I34.2 Nonrheumatic mitral (valve) stenosis
I05.2 Rheumatic mitral stenosis with insufficiency
Q23.2 Congenital mitral stenosis
I05.1 Rheumatic mitral insufficiency
394.0 Mitral stenosis
424.0 Mitral valve disorders
394.1 Rheumatic mitral insufficiency
394.2 Mitral stenosis with insufficiency
746.5 Congenital mitral stenosis
79619009 Mitral valve stenosis (disorder)
86466006 Rheumatic mitral stenosis (disorder)
194727002 Non-rheumatic mitral valve stenosis
194726006 Mitral stenosis with insufficiency (disorder)
82458004 Congenital stenosis of mitral valve (disorder)
Asymptomatic patients may be followed clinically with yearly exams for development of symptoms with periodic echo to evaluate valve area.
Once symptoms of MS develop, initiate appropriate medical therapy but advise patient that for most, surgical therapy will be needed to prolong survival. Almost all cases of MV stenosis progress in severity over time.
MS often presents during the intrapartum period. For patients with known severe MS, intervention should be pursued prior to pregnancy. Pregnancy in a patient with severe MS has a high rate of both maternal and fetal complications, including death.