Mitral Stenosis

Key points

• Causes: rheumatic fever (× 3!); rarer — mucopolysaccharidoses, carcinoid, endocardial fibroelastosis.
• Features: mid-late diastolic murmur (best in expiration) · loud S1 · opening snap · low-volume pulse · malar flush · atrial fibrillation.
• Severe MS: murmur lengthens; opening snap moves closer to S2.
• Mitral valve area: normal 4–6 cm²; 'tight' MS < 1 cm².
• CXR: left atrial enlargement (double right heart border, splayed carina). Percutaneous mitral valvotomy is intervention of choice for severe MS; contraindicated if MVA > 1.5 cm².

Decision points in this pathway

• Severe/symptomatic MS?

The full step-by-step algorithm, including what to do at each branch, opens in the app for approved members.