Mitral Stenosis

Question 1

what is the definitions of mitral valve stenosis?

Answer 1

• Obstruction of left ventricle inflow that prevents proper filling during diastole. Mitral stenosis is a narrowing of the mitral valve orifice, usually caused by rheumatic valvulitis producing fusion of the valve commissures and thickening of the valve leaflets.

Question 2

what is the epidemiology of mitral valve stenosis?

Answer 2

• The condition is more common in men than women

- incidence reducing due to reduction in rheumatic fever

Question 3

what is the aetiology of mitral valve stenosis?

Answer 3

• Most common cause of mitral stenosis is rheumatic heart disease secondary to rheumatic fever due to infection with group A beta-haemolytic streptococcus e.g. Streptococcus Pyogenes. Inflammation due to rheumatic fever leads to commissural fusion and a reduction in mitral valve orifice area, causing the characteristic doming pattern seen on echocardiography
• Infective endocarditis (3.3%)
• Mitral annular calcification (2.7%) - rarely leads to mitral stenosis if extensive, particularly in elderly patients and those with end-stage renal disease

Question 4

what are the risk factors for mitral valve stenosis?

Answer 4

• History of rheumatic fever
• Untreated streptococcus infections
• female
• ergot medications
• serotonergic medications

Question 5

what is the pathophysiology of mitral valve stenosis?

Answer 5

• Normal mitral valve area is 4-6cm2, symptoms begin at areas less than 2cm2
• Thickening and immobility of the valve leads to obstruction of blood flow from the left atrium to the left ventricle
• In order for sufficient cardiac output to be maintained, the left atrial pressure increases and left atrial hypertrophy and dilatation occur
• Consequently pulmonary venous, pulmonary arterial and right heart pressures also increase
• The increase in pulmonary capillary pressure is followed by the development of pulmonary oedema - this is seen particularly when atrial fibrillation occurs, due to the elevation of left atrial pressure and dilatation, with tachycardia and loss of coordinated atrial contraction
• This is partially countered by alveolar and capillary thickening and pulmonary arterial vasoconstriction (reactive pulmonary hypertension)
• Pulmonary hypertension leads to right ventricular hypertrophy, dilatation and failure with subsequent tricuspid regurgitation

Question 6

what are the key presentations of mitral valve stenosis?

Answer 6

orthopnoea
presence of risk factors
history of rheumatic fever
Progressive dyspnoea - due to left atrial dilation resulting in pulmonary congestion (reduced emptying), which is worse with; exercise, fever, tachycardia and pregnancy

Question 7

what are the signs of mitral valve stenosis?

Answer 7

Right heart failure, atrial fibrillation, systemic emboli, prominent a wave in jugular venous pulsations, mitral facies, diastolic murmur, sound opening S1 snap

Question 8

what are the symptoms of mitral valve stenosis?

Answer 8

Haemoptysis (coughing up blood) , pink cheeks

Question 9

what is the first line investigation for mitral valve stenosis?

Answer 9

- ECG: 
• Atrial fibrillation 
• Left atrial enlargement 
- Echocardiogram: 
• GOLD STANDARD for diagnosis 
• Assess mitral valve mobility, gradient and mitral valve area
CXR: 
• Left atrial enlargement 
• Pulmonary oedema/congestion 
• Occasionally calcified mitral valve
transthoracic echocardiography

Question 10

what is the differential diagnosis of mitral valve stenosis?

Answer 10

mitral valve regurgitation
left atrial myxoma
unexplained atrial fibrillation

Question 11

how is mitral valve stenosis managed?

Answer 11

Mitral stenosis is a mechanical problem and medical therapy does not prevent progression
first line = no treatment
severe disease:
- Beta-blockers e.g. Atenolol and digoxin which control heart rate and thus prolong diastole for improved diastolic filling
- Diuretics for fluid overload e.g. Furosemide
- Percutaneous mitral balloon valvotomy:
Catheter is inserted into the right atrium via the femoral vein under local anaesthesia
The interatrial septum is then punctured and the catheter advanced into the left atrium and across the mitral valve
The balloon is inflated and puts pressure on valve thereby separating the leaflets thereby increasing the size of the mitral valve opening thus enabling more blood to flow from left atrium into left ventricle
- Mitral valve replacement

Question 12

how is mitral valve stenosis monitored?

Answer 12

periodic monitoring

Question 13

what are the complications of mitral valve stenosis?

Answer 13

high blood pressure, heart failure, pulmonary oedema, atrial fibrillation, blood clots

Question 14

what is the prognosis for mitral valve stenosis?

Answer 14

10 year survival rate - 50-60%, 80% if asymptomatic

Question 15

what are the heart sounds associated with mitral stenosis?

Answer 15

loud S1, opening snap, low pitched mid diastolic murmur, apical diastolic thrill