Mitral Stenosis Flashcards
What is the cause of the mitral stenosis?
Almost invariably due to prior rheumatic fever
Mitral stenosis is the most common chronic valvular lesion with rheumatic fever
What is rheumatic fever?
Auto-immune reaction to Group A Streptococci infection of pharynx
What does RF affect?
affects heart (all cardiac tissues), skin, joints, and brain
What damage does RF do?
most important damage: heart valves (scarring) –> valve stenosis + / or regurgitation years later
To prevent recurrent RF?
chronic Penicillin
What is the next common target after mitral valve in RF?
aortic valve
What is the criteria used for diagnosis of ARF?
Jones Criteria
What is Jones criteria?
requires:
evidence of recent Group A Strep infection
AND
2 MAJOR diagnostic criteria,
OR
1 MAJOR and 2 Minor diagnostic criteria
What are signs of recent GAS infection?
throat swab culture growing Strep. A bacteria
Antibodies to Strep. toxin (Anti-Streptolysin O Titer = ASOT)
recent scarlet fever (well defined
severe Strep. throat infection plus
with rash)
What are Jones’ major criteria?
carditis (all layers of heart)
migrating joint inflammations (polyarthritis)
rash (moving, red, central clearing=erythema marginatum)
skin nodules (subcutaneous)
chorea (involuntary smooth limb movements= ‘St. Vitus’ dance’)
What are Jones’ Minor Criteria?
fever
blood tests showing inflammation (e.g. increased white blood cell count, high Erythrocyte sedimentation rate [ESR])
arthralgias (joint pains, but NO inflammation)
increased PR interval on ECG
What symptoms would you expect early on after developing major mitral stenosis and why?
Dyspnea because:
Increased LA pressure
- -> increased pulmonary venous + capillary pressures - -> increased pressure driving fluid into lungs - -> increased stiffness of lungs and work of breathing
In mitral stenosis when would dyspnea more prominent?
In periods of increased heart rate (shorter diastole)
or in increased flow states (exercise/anemia/fever…)
What kind of dyspneas can occur in MS?
ORTHOPNEA
and
PAROXYSMAL NOCTURNAL DYSPNEA
What is orthopnea?
Dyspnea upon lying flat due to:
- -> immediate increase in venous return from blood pooled in lower extremities
- -> increased flow across MV –> dyspnea
What is paroxysmal nocturnal dyspnea?
Sudden dyspnea after lying flat for hours due to:
slow reabsorption of tissue fluid–> increased venous return –> sudden dyspnea awakens
Why does hemotypsis occur in MS?
increased LA pressure –>
increased pulmonary venous pressure
–> fragile bronchial vein connections with pulmonary veins
–> increased chance rupture of bronchial veins
--> Bleed into lungs ( hemoptysis)
Why does fatigue occur in MS?
–> increased LA pressure leads to:
increased pulmonary venous pressure
increased pulmonary artery pressure
–>pulmonary artery intimal scarring
–> increased pulmonary artery pressure
–> Right Ventricular pressure
–> RV dilation and failure
–> insufficient forward output
↓pulmonary congestion /edema/dyspnea + FATIGUE / Edema / Ascites (backpressure)
Why does MS lead to arrythmias?
–> LA pressure –> increased LA enlargement
increased likelihood LA ‘short circuits’
–> chaotic atrial rhythm = atrial FIBRILLATION
What is atrial fibrilation?
- -> no organized atrial contraction, atria ‘jiggle’
- sluggish flow, blood clots, and EMBOLI (esp @ LA appendage –> stroke) - -> loss of ‘atrial kick’
- insufficient forward output
- Sudden increase in DYSPNEA / FATIGUE - -> leads to increase of HR
- less time in diastole, so less volume goes through MS
- sudden dyspnea/fatigue
T or F: any long-standing left heart valve disease and any heart failure type can increase risk of atrial fibrillation
T
What is the most common cause of aFib in NA?
in N. America, most common causes = age + hypertension –> ‘stiff’ LV –> ↑LA pressure –> LA enlargement –> Afib risk
T or F: most aFib patients need HR control meds
T
What kind of heart sounds are felt in MS?
Loud S1:
thickened leaflets / chords –> generate louder sound (even palpable)
when rigid, calcified, S1 intensity gradually lower
Opening Snap:
sound from MV opening (counterpart to loud S1)
also disappears once valve becomes rigid, severely calcified
What kind of sound can be heard during diastole?
MV turbulent flow–> murmur:
low-pitched ‘rumble’
in normal rhythm, atrial kick –> increased intensity = ‘pre-systolic accentuation’
the worse the MS, the longer into diastole the murmur lasts (longer time for pressure gradient to disappear)
T or F: MS can sometimes lead to RV overload
T: happens later in the course
What happens in RV overload?
enlarged, hypertrophied RV causes palpable lift underneath sternum = ‘parasternal lift’ or ‘RV heave’
right-sided S3 / S4 (abnormal RV diastolic function)
dilated RV –> stretches tricuspid annulus –> leaky tricuspid valve = tricuspid regurgitation
What kind of tests would be ordered if MS is suspected?
- ECG
- CXR
- echocardiography
- cardiac catherization
What kind of info can ECG give for MS?
enlarged LA
RV hypertrophy
Atrial fibrillation
What kind of info can CXR give for MS?
calcified MV, enlarged LA
pulmonary venous engorgement
pulmonary interstitial edema (‘Kerley B lines’)
pulmonary alveolar edema (if severe)
(late) RV enlargement, enlarged Pulm. arteries
What kind of info can Echo give for MS?
actually see the valve ‘in action’
assess severity of MS
assess pressure gradient across MV
assess other valves, as well as LV / RV function
What kind of info can cath give for MS?
tubes inserted into right / left heart / aorta / PA
able to measure pressures and flows directly
check for coronary disease if needing surgery
How to prevent MS?
Preventing rheumatic fever:
early treatment of Group A Strep pharyngitis
Preventing recurrences of rheumatic fever:
monthly intra-muscular Penicillin shots (till age 40, or 10 years after last attack)
Endocarditis prophylaxis—NO!:
NO antibiotics prior to dental cleaning
How to medically treat MS?
Diuretics:
decrease volume load on LA / lungs / RV
Rate-slowing drugs (especially in Afib):
slower heart rate –> increase diastole to empty LA
–> beta-blockers, (digoxin), some calcium channel blockers (Verapamil, Diltiazem)
Anticoagulant (Coumadin = Warfarin): if Afib (>20% annual stroke / embolic rate) if severe MS, prior emboli, or severe heart failure
What treatment would be good for MS to delay surgical replacement?
Balloon Valvuloplasty
Useful if MV still relatively pliable, not too severely calcified
Commissurotomy
now done ‘open-heart’ with cardio-pulmonary bypass machine, LA opened and surgeon cuts open MV commissures under direct vision
–> re-establishes two flaps
What are indication for valve replacement?
Valve replacement if major symptoms, valves not suitable for balloon / surgical repair
T or F: both types of valves require coumadin
F:
tissue–> lifelong antiplatelet
mech –> coumadin + aspirin
