**Question:** All except one are each feature of acute pericarditis

A. Cardiac tamponade
B. Electrolyte imbalance
C. Pleural effusion
D. Acute myocardial infarction

**Core Concept:** Acute pericarditis is an inflammation of the pericardium, the membrane that surrounds the heart, leading to symptoms and signs related to inflammation and irritation of the heart and surrounding structures.

**Why the Correct Answer is Right:** Acute pericarditis presents with symptoms and signs related to inflammation and irritation of the heart and surrounding structures. Cardiac tamponade is a condition where fluid accumulation causes compression of the heart chambers, leading to reduced cardiac filling and decreased cardiac output. Electrolyte imbalance and acute myocardial infarction are related to cardiac ischemia and infarction, not pericarditis. Pleural effusion occurs when fluid accumulates in the pleural space, causing friction and respiratory distress, but it is not a feature of acute pericarditis.

**Why Each Wrong Option is Incorrect:**

- Cardiac tamponade is a condition resulting from fluid accumulation, not a symptom or feature of acute pericarditis.
- Electrolyte imbalance and acute myocardial infarction are consequences of cardiac ischemia and infarction, not acute pericarditis.
- Pleural effusion occurs with fluid accumulation in the pleural space, not in the pericardium, which is the primary site of pericarditis inflammation.

**Clinical Pearl:** Acute pericarditis typically presents with a combination of symptoms like chest pain, fever, and cardiac tamponade, among others. It is essential to differentiate between these conditions to initiate appropriate therapy and management.

**Correct Answer:** D. Acute myocardial infarction

**Explanation:** The correct answer is "D. Acute myocardial infarction" because it is not a feature of acute pericarditis but rather a consequence of cardiac ischemia and infarction. Acute pericarditis typically presents with symptoms and signs related to inflammation and irritation of the pericardium and surrounding structures, not myocardial ischemia and infarction.