**Question:** Characteristic feature of Rheumatic carditis is:

A. Presence of rheumatic fever
B. High-grade fever
C. Cardiac enlargement
D. Absence of cardiac symptoms

**Core Concept:**
Rheumatic carditis is a complication of rheumatic fever that affects the heart. Rheumatic fever is a post-infectious inflammatory condition that occurs following group A beta-hemolytic streptococcal pharyngitis or scarlet fever infection. The carditis typically involves the mitral and/or aortic valves, leading to inflammation, damage, and dysfunction.

**Why the Correct Answer is Right:**
Rheumatic carditis is characterized by the presence of rheumatic fever, which is a post-infectious inflammatory condition resulting from group A streptococcal infections. Among the provided options, the correct answer is A: Presence of rheumatic fever, as it directly relates to the underlying cause and primary feature of rheumatic carditis.

**Why Each Wrong Option is Incorrect:**

A. High-grade fever (Option B) is a symptom of rheumatic fever but not a defining feature of rheumatic carditis. The focus should be on the presence of rheumatic fever, not fever severity.

C. Cardiac enlargement (Option C) is a potential consequence of rheumatic carditis, but it is not the defining feature of the condition. The core aspect is the presence of rheumatic fever, not the cardiac enlargement itself.

D. Absence of cardiac symptoms (Option D) contradicts the definition of rheumatic carditis, which involves inflammation and dysfunction of the heart valves. The focus should be on the presence of rheumatic fever and its cardiac involvement, not the absence of cardiac symptoms.

**Clinical Pearl:**

Rheumatic fever is a severe complication of group A streptococcal infections, particularly following untreated streptococcal pharyngitis or scarlet fever. Prompt diagnosis and treatment are crucial to prevent progression to rheumatic carditis and its potentially severe consequences on heart valves and other organs.

**Correct Answer:**
A. Presence of rheumatic fever, as it represents the underlying cause and primary feature of rheumatic carditis.