The QRS comxplex in an ECG is not related to :

Options

A. Ventricular contraction
B. A measure of determining the heartbeat
C. Stroke volume of the cardiac cycle
D. Ventricular repolarisation

Answer

To solve the question regarding the QRS complex in an ECG, we will analyze each of the options provided and determine which one is not related to the QRS complex.

### Step-by-Step Solution:

1. **Understanding the QRS Complex**:
The QRS complex in an electrocardiogram (ECG) represents the electrical depolarization of the ventricles. This is the phase when the ventricles contract to pump blood out of the heart.

**Hint**: Remember that the QRS complex is primarily associated with ventricular activity.

2. **Analyzing the Options**:
- **Option A: Ventricular Contraction**:
The QRS complex is indeed related to ventricular contraction, as it represents the depolarization that leads to this contraction.

**Hint**: Think about what happens in the heart during the QRS complex.

- **Option B: A Measure of Determining the Heartbeat**:
The ECG, including the QRS complex, is used to measure heartbeats. Thus, this option is also related to the QRS complex.

**Hint**: Consider how ECGs are used in clinical settings.

- **Option C: Stroke Volume of the Cardiac Cycle**:
The stroke volume is the amount of blood pumped by the ventricles with each heartbeat. Since the QRS complex indicates when the ventricles contract, it is related to stroke volume.

**Hint**: Relate stroke volume to the function of the ventricles during contraction.

- **Option D: Ventricular Repolarization**:
The QRS complex does not represent ventricular repolarization; instead, ventricular repolarization is indicated by the T wave in the ECG.

**Hint**: Identify which part of the ECG corresponds to repolarization.

3. **Conclusion**:
Based on the analysis, the QRS complex is not related to **ventricular repolarization**. Therefore, the correct answer is **ventricular repolarization**.

### Final Answer:
The QRS complex in an ECG is not related to **ventricular repolarization**.