Mitral stenosis

Question 1

Aetiology

Answer 1

MOST COMMON = rheumatic heart disease (Rheumatic fever develops 2-4 weeks after throat infection or scarlet fever due to Group A Streptococcus pyogenes infection)
Less common:
- valve calcification (typically older Px)
- infective endocarditis

Question 2

Definition

Answer 2

Narrowing of the mitral valve resulting in obstruction to left ventricular inflow that impairs LV diastolic filling
(normal mitral valve area = 4/6cm^2, Sx begin when valve area <2cm^2)

Question 3

Pathophysiology

Answer 3

Narrowing of the mitral valve resulting in obstruction to left ventricular inflow that impairs LV diastolic filling → left atrial pressures increase to maintain CO→ left atrial hypertrophy hypertrophy (due to pressure overload) → increased pressure in pulmonary veins & arteries
- Increased pulmonary pressures cause pulmonary oedema→ dyspneoa AND haemoptysis due to rupturing of bronchial vessels
- Increased risk of ATRIAL FIBRILLATION due to LAH → palpitations & risk of embolic ischaemic stroke & thromboembolism
- Pulmonary hypertension increases afterload of RV→ RV hypertrophy with tricuspid regurgitation & eventual right-heart failure → may get Sx of RHF e.g. raised JVP, peripheral oedema, ascites, hepatosplenomegaly

Question 4

Signs & symptoms (3 each)

Answer 4

SIGNS
- Low-pitched mid-diastolic rumbling murmur, loudest at apex (5th IC, Left midclavicular line) with patient in held expiration on LHS (remember RILE- left sided valve defects heard on expiration)
- loud S1 snap (due to sudden closing of thickened mitral valve cusps)?
- Prominent ‘a’ wave on jugular venous pulsations (represents atrial systole, hypertrophied left atrium generates higher pressures during atrial systole part of diastole)

SYMPTOMS
- malar flush = plum-red discoloration of cheeks (stasis in LA causes CO2 retention, CO2 is a systemic vasodilator) DDx: can get plethoric complexion in Cushing’s & polycythaemia vera
- dyspnoea (due to pulmonary oedema due to pulmonary hypertension)
- haemoptysis (due to rupture of bronchial vessels)

+/- symptoms of atrial fibrillation (palpitations, irregularly irregular pulse, tachycardia)

Question 5

Invetsigations

Answer 5

• GS = Transthoracic echocardiogram- assesses valve area (Sx begin when area <2cm^2)& pressure gradient across mitral valve
• ECG - shows P. mitrale (bifid P waves in lead II due to left atrial enlargement); may show atrial fibrillation (absent P waves, narrow QRS complex, irregularly irregular pulse)
• CXR - shows left atrial enlargement

Question 6

Treatment

Answer 6

Asymptomatic patients: monitor with serial transthoracic echo

Symtpomatoc patients:
1st line = percutaneous balloon valvotomy/valvuloplasty (balloon-catheter inflated across stenosed mitral valve in LA)
2nd line e.g. for severe disease= surgical mitral valve replacement