Cardio - Mitral Stenosis

Question 1

suggest possible causes for MS

Answer 1

• infection: rheumatic fever (most common cause), infective endocarditis with large vegetations
• inflammatory: SLE, RA
• degenerative calcification
• infiltration: amyloid deposition, carcinoid syndrome, left atrial myxoma
• congenital mitral stenosis

Question 2

describe the downstream pathological effects of mitral stenosis

Answer 2

MS causes increased pressure in LA (to try and force more blood into LV)…

1. increased pressure in pulmonary system and thus in RV… RV dilation… tricuspid regurgitation and RHF
2. LA dilation… AF and stasis of blood flow in left atrial appendage - risk of thromboemboli

Question 3

describe the possible symptoms of MS. explain why these occur

Answer 3

Pts may be asymptomatic for many yrs and then present with gradual decrease in activity.

1. progressive dyspnoea (main Sx) - can be on exertion (CO unable to increase enough above resting through stenosed valve, and high pressures transmitted to pulmonary vasculature),
   orthopnoea or PND (due to LHF)
2. palpitations, fatigue, dyspnoea, lightheadedness (due to AF causing low CO)
3. haemoptysis (due to sudden rupture of a bronchial vein)
4. symptoms of systemic emboli (rare presentation), e.g. stoke, abdo. pain…
5. Ortner syndrome may occur when a massively enlarged left atrium compresses left recurrent laryngeal n. causing a hoarse voice

Question 4

What signs might be visible on observation of a pt with MS?

Answer 4

1. malar flush/mitral facies (rare) - produced by chronic low CO state combined with systemic vasoconstriction
2. increased JVP - prominent ‘A wave’ due to vigorous atrial contraction

Question 5

suggest 2 signs that may be present on palapation of a pt with MS

Answer 5

1. tapping apex beat (opening snap of MV)

2. right ventricular heave (due to RHF)

Question 6

describe the murmur heard in a pt with MS

Answer 6

• low-pitched, mid-diastolic rumble (opening snap, decrescendo, crescendo)
• best heard with pt in left lateral position with bell of stethoscope

Question 7

which investigations would you perform on a pt with suspected MS?

Answer 7

1. ECG - may show AF, LA enlargement and RV hypertrophy
2. CXR - may show LA enlargement and interstitial oedema (Kerley A and B lines) if severe, mitral valve calcification or prominent pulmonary vessels with redistribution of pulmonary vasculature to upper lobes
3. Echocardiography - key Dx tool (TTE usually sufficient), assesses severity and consequences of MS as well as pulmonary artery pressures, associated valve diseases and LA size

Question 8

How would you manage a pt with asymptomatic MS?

Answer 8

If significant MS - follow-up annually via clinical and echo examinations

If mild-moderate MS - follow-up ever 2-3 yrs

Question 9

How would you manage a pt with symptomatic MS?

Answer 9

1. Medical therapy
   - diuretics to relieve dyspnoea
   - B-blockers or CBBs can improve exercise tolerance
   - anticoagulation in pts with permanent or paroxysmal AF
2. Surgical therapy
   - percutaenous mitral commissurotomy: for pts with severe MS or those with pulmonary hypertension
   - surgical valve replacement: for pts in whom PMC is contra-indicated, e.g. mitral valve area >1.5cm2

Question 10

What is the prognosis for MS?

Answer 10

For pts with no or minimal Sx, 10yr survival is very good.

But poor if pts have limiting Sx and untreated MS. Mean survival <3 yrs when severe pulmonary HTN develops.

Question 11

Suggest possible complications of MS

Answer 11

1. pulmonary hypertension
2. AF
3. thromboembolic events, e.g. stroke, mesenteric ischaemia
4. RHF
5. infective endocarditis