Which of the following changes in ECG indicates that a person is having a heart attack?

Options

A. Enlargement of P-wave
B. Depressed S-T segment
C. Elevated S-T segment
D. Flat T -wave

Answer

To determine which change in the ECG indicates that a person is having a heart attack, we will analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Understanding the ECG Components**:
- The ECG (electrocardiogram) consists of several waves: P wave, QRS complex, and T wave. Each of these waves represents different electrical activities of the heart. The P wave indicates atrial depolarization, the QRS complex indicates ventricular depolarization, and the T wave indicates ventricular repolarization.

**Hint**: Familiarize yourself with the components of an ECG and their significance in heart activity.

2. **Analyzing the Options**:
- **Option 1: Enlargement of P wave**:
- An enlarged P wave typically indicates atrial enlargement, which is not directly related to a heart attack. Therefore, this option is incorrect.

**Hint**: Consider what each wave signifies and how changes in size can relate to heart conditions.

- **Option 2: Depressed ST segment**:
- A depressed ST segment is often associated with myocardial ischemia, which indicates reduced blood flow to the heart muscle but does not specifically indicate a heart attack. Thus, this option is also incorrect.

**Hint**: Understand the implications of ST segment changes and their relationship to heart conditions.

- **Option 3: Elevated ST segment**:
- An elevated ST segment is a significant indicator of a heart attack (myocardial infarction). This elevation suggests that there is damage to the heart muscle, which is a critical sign of a heart attack. Therefore, this option is correct.

**Hint**: Remember that ST segment elevation is a key diagnostic criterion for heart attacks.

- **Option 4: Flat T wave**:
- A flat T wave can indicate various conditions, including hypokalemia (low potassium levels), but it does not specifically indicate a heart attack. Thus, this option is incorrect.

**Hint**: Differentiate between the implications of T wave changes and their relevance to heart attacks.

3. **Conclusion**:
- Based on the analysis of all options, the change in the ECG that indicates a person is having a heart attack is the **elevated ST segment**.

### Final Answer:
The correct answer is **elevated ST segment**.