A 38-year-old woman with a history of rheumatic fever presents with a mid-diastolic murmur best heard at the apex. Which is the most common valve involved in chronic rheumatic heart disease?

Explanation

## Valve Involvement in Rheumatic Heart Disease **Key Point:** The mitral valve is affected in >65% of all cases of chronic rheumatic heart disease, either in isolation or in combination with other valves. ### Frequency of Valve Involvement | Valve | Frequency | Pattern | |-------|-----------|----------| | Mitral alone | ~40% | Stenosis > Regurgitation | | Mitral + Aortic | ~20% | Most common combined lesion | | Aortic alone | ~10% | Regurgitation > Stenosis | | Tricuspid | ~5% | Usually secondary to RV dilation | | Pulmonary | <1% | Extremely rare | ### Pathophysiology of Mitral Involvement 1. **Acute rheumatic fever** causes inflammation of all three cardiac layers (pancarditis) 2. **Mitral valve** is most susceptible because: - Highest pressure gradient across the valve during systole - Leaflets experience maximum mechanical stress - Endocardium most exposed to turbulent flow 3. **Chronic sequelae** → commissural fusion, leaflet thickening, and calcification **High-Yield:** Mitral stenosis is the most common *functional* lesion in chronic rheumatic heart disease globally, particularly in developing countries like India where acute rheumatic fever remains prevalent. **Clinical Pearl:** The mid-diastolic murmur described in this case is pathognomonic for mitral stenosis — best heard at the apex with the patient in the left lateral decubitus position, and often preceded by an opening snap. **Mnemonic:** **MiTRAL** = **M**itral (most common), **T**ricuspid (secondary), **R**are aortic/pulmonary in isolation.