In ECG P-R interval is prolonged due to

Options

A. myocardial ischemia
B. bradycardia
C. tachycardia
D. cardiomegaly

Answer

### Step-by-Step Solution:

1. **Understanding the PR Interval**:
- The PR interval in an ECG represents the time taken for electrical impulses to travel from the atria (A) to the ventricles (V). It is measured from the beginning of the P wave to the beginning of the QRS complex.

2. **Significance of Prolonged PR Interval**:
- A prolonged PR interval indicates a delay in the conduction of electrical impulses from the atria to the ventricles. This can lead to a slower heart rate because the impulses are not reaching the ventricles quickly enough.

3. **Analyzing the Options**:
- **Option 1: Myocardial Ischemia**: This condition involves insufficient blood flow to the heart muscle, which does not directly affect the PR interval.
- **Option 2: Bradycardia**: This refers to a slower than normal heart rate. Since a prolonged PR interval results in delayed conduction, it can lead to bradycardia.
- **Option 3: Tachycardia**: This is an increased heart rate, which is the opposite of what happens with a prolonged PR interval.
- **Option 4: Cardiomegaly**: This refers to an enlarged heart, which may not directly relate to the PR interval.

4. **Conclusion**:
- The correct answer is **bradycardia** (Option 2), as a prolonged PR interval results in a slower heart rate due to delayed conduction of impulses.