A 28-year-old woman from rural India presents with dyspnea on exertion and palpitations for 6 months. On examination, she has a loud S1, opening snap, and a mid-diastolic murmur best heard at the apex in the left lateral decubitus position. Chest X-ray shows straightening of the left heart border and pulmonary congestion. Which investigation is most appropriate to confirm the diagnosis and assess severity of mitral stenosis?

Explanation

## Investigation of Choice in Rheumatic Mitral Stenosis ### Why Transthoracic Echocardiography with Doppler? **Key Point:** Transthoracic echocardiography (TTE) with Doppler is the gold standard non-invasive investigation for diagnosis and hemodynamic assessment of mitral stenosis in rheumatic heart disease. **High-Yield:** TTE provides: - Direct visualization of the stenotic mitral valve leaflets (thickened, calcified, restricted motion) - Measurement of mitral valve area (MVA) using planimetry or pressure half-time method - Doppler assessment of transmitral gradient - Left atrial size and function - Assessment of associated lesions (aortic, tricuspid involvement) - Screening for thrombus in the left atrium ### Clinical Application **Clinical Pearl:** The opening snap heard on auscultation correlates with valve mobility — a finding that TTE directly visualizes. The mid-diastolic murmur reflects the pressure gradient across the stenotic valve, which Doppler quantifies. ### Severity Grading by Echocardiography | Parameter | Mild MS | Moderate MS | Severe MS | |-----------|---------|-------------|----------| | MVA (cm²) | >1.5 | 1.0–1.5 | <1.0 | | Mean gradient (mmHg) | <5 | 5–10 | >10 | | LA size (mm) | <40 | 40–50 | >50 | ### Why TTE is First-Line 1. Non-invasive, repeatable, no radiation 2. Excellent acoustic windows in most patients 3. Provides complete anatomic and hemodynamic data 4. Guides management decisions (medical vs. interventional) 5. Cost-effective in resource-limited settings (relevant to Indian population) [cite:Harrison 21e Ch 297]