Why do you get haemoptysis (coughing up blood) in mitral stenosis?

Hemoptysis in Mitral Stenosis: Pathophysiological Mechanism

Hemoptysis in mitral stenosis occurs due to pulmonary venous hypertension leading to bronchial venous engorgement, rupture of dilated bronchial veins, and formation of pulmonary varices that can bleed when pressure exceeds vascular integrity.

Pathophysiological Cascade

Mitral stenosis creates a mechanical obstruction that leads to a series of hemodynamic changes resulting in hemoptysis:

1. Left Atrial Pressure Elevation

   • Narrowed mitral valve orifice (area <1.5 cm²) obstructs blood flow from left atrium to left ventricle 1
   • Increased resistance across the valve creates a pressure gradient
   • Left atrial pressure rises significantly, especially during exertion

2. Pulmonary Venous Hypertension

   • Elevated left atrial pressure transmits backward into pulmonary veins
   • Chronic venous congestion develops throughout the pulmonary vasculature
   • Bronchoscopic examination can visualize this venous congestion 2

3. Pulmonary Capillary Pressure Elevation

   • Sustained high pressure in pulmonary veins leads to capillary congestion
   • Capillary pressure may exceed oncotic pressure, causing fluid extravasation

4. Vascular Adaptations and Complications

   • Formation of bronchial-pulmonary venous anastomoses (pulmonary varices) 3
   • Dilation and engorgement of bronchial veins
   • Rupture of these thin-walled vessels when pressure exceeds vascular integrity

5. Pulmonary Apoplexy

   • In severe cases, massive and sudden hemoptysis can occur
   • This dramatic presentation is termed "pulmonary apoplexy" 4
   • Represents an emergency requiring immediate intervention

Clinical Significance

• Hemoptysis is more common in severe mitral stenosis (valve area <1.0 cm²) with mean gradient >10 mmHg 1
• Pulmonary artery systolic pressure often exceeds 50 mmHg in patients who develop hemoptysis 5
• Hemoptysis may be the presenting symptom in patients with previously undiagnosed mitral stenosis 2
• The presence of hemoptysis often indicates advanced disease requiring intervention 6

Management Implications

• Hemoptysis in mitral stenosis is a strong indication for valve intervention
• Percutaneous mitral commissurotomy is preferred for patients with favorable valve anatomy 1
• Mitral valve replacement is indicated when valve morphology is unfavorable 6
• Conservative management may temporarily resolve symptoms, but definitive valve intervention is necessary 4

Hemoptysis in mitral stenosis represents the culmination of chronic pulmonary venous hypertension leading to vascular remodeling and ultimately vessel rupture. It signals advanced disease and the need for prompt evaluation and intervention to prevent recurrence and potential life-threatening complications.