During acute myocardial infraction which of the following changes occurs in the ECG ?

Options

A. Flattened T wave
B. Depressed ST segment
C. Elevated ST segment
D. Increased length of PQ interval

Explanation

**Step-by-Step Solution:**

1. **Understanding Myocardial Infarction**: Acute myocardial infarction (AMI), commonly known as a heart attack, occurs when blood flow to a part of the heart is blocked, leading to damage or death of heart muscle tissue.

2. **ECG Basics**: An electrocardiogram (ECG) measures the electrical activity of the heart. Key components include:
- P wave: Atrial depolarization
- QRS complex: Ventricular depolarization
- T wave: Ventricular repolarization
- ST segment: The period between ventricular depolarization and repolarization.

3. **Analyzing the Options**:
- **Flattened T wave**: T waves can be positive, negative, or biphasic but are not typically flat.
- **Depressed ST segment**: This indicates ischemia (reduced blood flow) but is not specific to myocardial infarction.
- **Elevated ST segment**: This is a classic sign of acute myocardial infarction. It indicates that there is a significant injury to the heart muscle.
- **Increased length of PQ interval**: This indicates a first-degree heart block, not myocardial infarction.

4. **Conclusion**: The most characteristic change in the ECG during acute myocardial infarction is the **elevated ST segment**. This indicates that there is damage to the heart muscle due to the lack of blood supply.

**Final Answer**: Elevated ST segment.

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