Least common valve involved in rheumatic fever-
**Core Concept**
Rheumatic fever is an autoimmune inflammatory process that primarily affects the heart, joints, and central nervous system, resulting from a group A beta-hemolytic streptococcal infection. The condition leads to the formation of Aschoff bodies and valve inflammation, which can cause valvular lesions and eventual heart failure.
**Why the Correct Answer is Right**
The mitral valve is the most commonly affected valve in rheumatic fever, accounting for approximately 75% of cases, due to its unique anatomy and high pressure environment. The involvement of the mitral valve is thought to be related to the turbulent flow of blood through the mitral valve, which may exacerbate inflammation. In contrast, the aortic valve is less commonly affected, likely due to its lower pressure environment and different anatomical characteristics.
**Why Each Wrong Option is Incorrect**
**Option A:** The tricuspid valve is occasionally affected in rheumatic fever, but it is less common than the mitral valve.
**Option B:** The pulmonary valve is rarely involved in rheumatic fever, as it is not exposed to the same level of pressure and flow as the other valves.
**Option C:** The least common valve involved in rheumatic fever is actually the aortic valve, which is more commonly affected than the tricuspid, pulmonary, or other valves.
**Clinical Pearl / High-Yield Fact**
In patients with rheumatic fever, the presence of mitral stenosis is a classic indication of a history of rheumatic heart disease, and its development often correlates with the severity of the initial valvular lesion.
**Correct Answer:** D.