Mitral Valve Disease-Merkin Flashcards
Definition of mitral stenosis
A disease in which the mitral valve area is decreased, requiring increased pressure gradient to drive the blood across the narrowed orifice.
Etiologies of mitral stenosis
Congenital (rare with CHF), Rheumatic HD (20-40y after fever), mitral annulus calcification, active endocarditis, rare (Carcinoid, whipple disease, mucopolysaccharidoses, Fabry’s)
What is rheumatic fever?
Autoimmune reaction to normal tissue (primarily the heart) initiated by Streptococcus pharyngitis Acute rheumatic fever may lead to a chronic complication: Rheumatic Heart Disease Mitral valve injury: thickening and fusion of the leaflets, shortening of the chords and calcification of the entire apparatus continuously and progressively. Usually damage is in women.
Pathophysiology of mitral stenosis
- Increased transvavlular pressure to push blood through stenosed valve–>dyspnea (from backup into lungs) and hemoptysis 2. Reduced CO, can’t exercise, forward cardiac output is low–> fatigue and lethargy 3. Blood Stagnation of blood in LA–>pressure and dilation of LA–>increased atrial fibrillation and thromboembolism a. 30-40% of pts with symptomatic mitral stenosis (moderate or severe) develop Afib b. 10-20% of pts with emboli to any part of body (including coronary artery–> acute MI) 4. High transmitral pressure gradient a. Mitral regurgitation–>higher flow into valve (more pressure leads to more symptoms (often develops during pregnancy)), renal failure b. Symptomatic during high fever and tachycardia i. Short diastole, pressure gradient btw LV and LA greater and leads to more symptoms since LA doesn’t have enough time to put through all CO needed.
What is the size of a normal mitral valve?
4-6cm^2
When do symptoms appear from small mitral valve size?
How does MS severity relate to mitral valve size?
Mild stenosis >1.5cm^2, critical/severe
Consequences of mitral stenosis
Mechanical obstruction at mitral valve–>increased LAP–>persistent diastolic gradient between LA/LV–>increased Pulmonary artery pressure–>increased right ventricular pressure
What part of the heart is spared in mitral stenosis?
Left ventricle
Complications related to mitral stenosis valve
Endocarditis (more likely on less rigid, mild MS)
Heart sounds in mitral stenosis
- Loud 1st sound when leaflets still pliable (not when heavily calcified, not useful for severity assessment), 2. Opening snap, 3. Diastolic murmur
What is the opening snap in mitral stenosis?
Related to maximal opening of mitral valve (double opening with M-shape), the higher the LA pressure the closer the snap to the end of S2- assessing severity of MS. May be confused with S3. Can also happen in MR, VSD, Tetrology of Fallot.
Diastolic murmur relating to severity
Same time period as S4, the longer is more severe, late diastolic murmur is light stenosis. Decrescendo.
ECG in mitral stenosis
May have no signs of MS or LA enlargement. But 90% of severe MS have LAE with sinus rhythm. RV hypertrophy only with longstanding HTN with systolic >70. Afib when symptomatic.
Echo in mitral stenosis
Diagnosis of MS and severity. Assessment of valve morphology to determine the therapeutic strategy. Complications (thrombus in LA, vegetations in endocarditis). Calcification is white. Anterior mitral leaflet doming but posterior leaflet doesn’t move. Measure opening of valve.
Prognosis of mild and mild/moderate mitral stenosis?
Can live asymptomatic for a long time
What is prognosis of MS once symptomatic?
Only on exertion: 10 year survival is 80%. If highly symptomatic (can’t walk up stairs)-20%/10y if untreated
What are the main causes of death in untreated mitral stenosis
CHF (mainly RHF-edema, pulmonary congestion, asciites), systemic embolism (CVA), pulmonary embolism, infection (rare, endocarditis)
Differential diagnoses with mitral stenosis
LA tumor (myxoma) may prolapse into opening of valve and cause symptoms of MS, congenital disease-Cor Triatum, usually known from childhood-membrane in LA mimicks MS
Therapeutic approach of asymptomatic mitral stenosis
Conservative approach
Therapeutic approach for symptomatic patients
Repair/replacement
What medical therapy is used for MS?
Beta blockers and Ca channel blockers reduce symptoms by reducing HR. Conversion of AF to sinus (verapamil), Anticoagulation for persistant Afib to prevent Afib.
What are the strategies to repair a stenosed mitral valve
Percutaneous mitral balloon valvuloplasty (PMBV), closed/open commissurotomy, valve replacement
What is the difference between an open and closd commisurotomy
Open is done on bypass machine, closed is done without, open only the LA and go through mitral valve with a finger or tool to break commisures of mitral valvee. If too calcified, need to replace the valve.
What are the benefits to a baloon valvuloplasty?
Reduces pressure gradient greatly.
What are the complications of balloon valvuloplasty?
If the valve breaks and is very noncompliant or calcified can cause mitral regurgitations. 2-3% will need surgery for acute mitral regurgitation and pulmonary edema, replace valve immediately. 7% remain with hole between atria. Thrombi can embolize anywhere in body. Contraindicated with thrombus in LA or MR.
Balloon valvuloplasty vs commisurotomy?
Similar mortality but balloon more successful, remain asymptomatic longer, but commisurotomy remain asymptomatic for years too, need to weigh risks.
What should be done in borderline patients?
If moderate stenosis but severe symptoms treat surgically (balloon). If thrombus present send for commissurotomy.
Etiology of ischemic mitral regurgitation
Disease of left ventricle, annular dilatation, papillary muscle dysfunction and rupture. Leaflets too far apart and can’t reach to close.
Etiology of non-ischemic mitral regurgitation
Calcification (annulus, leaflets, chords), degenerative (myxomatous) leaflets/chords, infection or rheumatic leaflets and chords (less common).
What is the most common cause of mitral regurgitation in the elderly?
Calcification
What is the most common cause of mitral regurgitation in younger patients?
Myxomatous/degenerative
Feature of mitral valve prolapase (myxomatous degenration of mitral valve)
Disease of leaflets or chords, leaflet goes back into LA during systole. Leaflets and chordae are enlarge/elongated, leaflets back into left atrium during systole, mid-systolic click and regurgitant murmur/late systolic.
When does mitral regurgitation occur in prolapse?
Latent, mid- or end-systolic
Incidence of mitral prolapse
5-10% of population, mostly asymptomatic for whole life, common in Marfan and other CT disorders. Strong genetic/hereditary component
When is mitral valve prolapse usually discovered?
Incidental finding in echo
Clinical features of mitral valve prolapse
Usually asymptomatic, otherwise chest pain, palpitations from arrhythmia, dyspnea, sudden death.
Pathophysiology of mitral regurgitation
Volume overload from valve–>compensatory LV dilation–>reduced wall tension–>reduced afterload–>contractile energy expanded more in shortening than in tension–>increased CO
What happens to the patient when the cardiac output changes?
Becomes symptomatic, can’t maintain proper CO during exercise, causes dyspnea. If untreated and process prolonged, causes LV failure and dilated LV, thin walls, high pressure and low CO–>irreversible myocardial damage.
Effects and symptoms of mitral regurgitation
LA enlargement, atrial fibrillation, increased LA pressure, increased Pulmonary artery wedge pressure (PAWP) and CHF. Irreversible depression of contractility, sudden death.
What are the heart sounds in mitral regurgitation
Diminished S1, wide splitting of S2 (aortic closes early in severe MR because low V/P in LV, late pulmonary valve closure from pulmonary hypertension), murmur at base of heart-systolic decreschendo in acute, holosystolic in chronic.
Other physical exam signs of mitral regurgitation
Signs of CHF early on left side and later on right side.
How is echo used in MR?
Diagnosis and severity assessment, valve morphology for therapy, complications diagnosis (thrombus, vegetations).
What medical therapy is used for MR?
Vasodilators (controversial in asymptomatic, not in normal ventricular function, for dilated LV), Beta blockers for CHF
What to consider for treatment in MR?
Symptoms, age, timing, comborbidity, LV function, ischemia or no, repair vs replacement.
Pre-op predictors of worse surgical outcomes in MR
Age > 75 NYHA > III, IV A-fibrillation high PCW, high PAP, LVEF < 0.50 LVESD >45 mm LAE (>7.0 cm2/m2) RVEF < 30%
How should a patient with ischemic heart disease and mitral dysfunction be treated?
ACE inhibitors improve MR
What is the most important factor for prognosis?
LV Ejection fraction. If >6, 10y survival is >70%. If
Factors in favor of observing over sending to surgery
Asymptomatic Normal LV size LVEF >0.60 Sinus rhythm Normal pulm. press Regular F/U feasible
Factors in favor of MV repair
Symptoms +/- LVESD >40cm LVEF
