Which of following is not recorded in ECG?

Options

A. Atrial depolarization
B. Atrial repolarization
C. Ventricular depolarization
D. Ventricular repolarization

Answer

To solve the question "Which of the following is not recorded in ECG?", we will analyze the options provided and understand the components of an electrocardiogram (ECG).

### Step-by-Step Solution:

1. **Understanding ECG**:
- An electrocardiogram (ECG) records the electrical activity of the heart over time. It shows the depolarization and repolarization of the heart's chambers.

2. **Components of ECG**:
- The main waves recorded in an ECG are:
- **P wave**: Represents atrial depolarization.
- **QRS complex**: Represents ventricular depolarization.
- **T wave**: Represents ventricular repolarization.

3. **Analyzing the Options**:
- Let's analyze the options provided:
- **Atrial depolarization**: This is recorded as the P wave in the ECG.
- **Atrial repolarization**: This is not distinctly visible in the ECG because it occurs during the QRS complex and is masked by the larger electrical activity of the ventricles.
- **Ventricular depolarization**: This is recorded as the QRS complex in the ECG.
- **Ventricular repolarization**: This is recorded as the T wave in the ECG.

4. **Identifying the Correct Answer**:
- Since atrial repolarization does not produce a distinct wave in the ECG and is masked by the QRS complex, it is the correct answer to the question.

### Conclusion:
The component that is **not recorded in ECG** is **Atrial Repolarization**.