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