Mitral Stenosis

Question 1

Define Mitral Stenosis

Answer 1

Mitral valve narrowing causing obstruction to blood flow from the left atrium to the left ventricle

Question 2

Explain the aetiology/Risk factors of Mitral Stenosis

Answer 2

• MAIN CAUSE: Rheumatic Fever Disease/Chronic Rheumatic Heart Disease (98%)
  
  • This occurs when a Streptococcal throat infection (Streptococcus pyogenes pharyngitis) isn’t treated properly
• Female sex
• Left atrial myxoma (a slow-growing tumour that obstructs mitral valve)
• Infective endocarditis (bacterial vegetation forms on valves) endocarditis typically targets Mitral vale

Question 3

Summarise the epidemiology of mitral stenosis

Answer 3

• Incidence is decreasing due to antibiotic use in the treatment of rheumatic fever disease
• More common in females

Question 4

Recognize the presenting symptoms of mitral stenosis? (5 + 3 RARE)

Answer 4

• ASYMPTOMATIC in early disease

1. Exertional Dyspnoea
2. Orthopnea (increased preload)
3. Paroxysmal Nocturnal Dyspnoea
4. Palpitations (depending on severe AF)
5. RHF symptoms: Ascites, Peripheral pitting oedema

RARE:

• Hoarseness/Ortner’s syndrome (left atrial enlargement may impinge on recurrent laryngeal nerve)
• Haemoptysis (increases in pulmonary venous pressure, especially during exercise, may rupture bronchiolar-pulmonary vein anastomoses)
• Atrial enlargement may cause dysphagia (extrinsic oesophageal compression)

Question 5

Recognise the signs on physical examination (8) + 4 signs of advanced MS

Answer 5

1. Mid/Late Diastolic murmur (low-pitched rumbling heard after S2, best heard at apex with patient in left lateral decubitus position/laying on left-side)
2. The OPENING SNAP of the mitral valve at the diastole (after S2) is very audible as it is forceful and the rumble is heard after
   
   • If the OPENING SNAP is heard very soon after S2, this indicates severe disease as the higher LA pressures force the valves open earlier and the rumble lasts longer as it takes blood longer to travel through the stenotic valve
3. Loud S1 is heard as the high atrial pressures force the valves far apart so they shut loudly
4. Loud P2 can also be heard (pulmonary HTN due to increased backflow from LA would snap pulmonary valve close)
5. Bi-basal crackles (Pulmonary oedema) on auscultation
6. Mitral facies (malar FLUSH/plethoric, cutaneous vasodilation due to CO2 retention)
7. Irregularly irregular pulse (if concomitant AF)
8. Palpable S1 at apex/tapping apex beat

ADVANCED MS CAUSING RHF:

1. Peripheral pitting oedema
2. Parasternal heave (due to RVH secondary to pulmonary HTN)
3. Raised JVP
4. Hepatomegaly/Ascites

Question 6

Identify appropriate investigations for mitral stenosis

Answer 6

• Trans-Thoracic Echocardiography (diagnostic - shows “hockey stick” appearance of the anterior mitral leaflet due to thickening)
• Chest X-Ray may show (non-specific)
  
  • Left atrial enlargement – double shadow in right cardiac silhouette as LA distends past RA
  • Pulmonary oedema
  • Kerley B lines (horizontal lines in lower lobes, indicating pulmonary venous congestion)
• ECG may show (non-specific)
  
  • atrial fibrillation
  • evidence of RVH if patient has PHTN (high amplitude R peak in V2,3,4)
  • left atrium enlargement is shown by a broad and bifid P wave (P mitrale)

Question 7

Complications of Mitral Stenosis

Answer 7

• Atrial Fibrillation
• Systemic emboli (thrombus may form due to stagnation e.g. STROKE, PVD)