## Medical Surgical Cardiac Fundamentals #3

### Question

The nursing student is reviewing electrocardiogram (ECG) strips. Which measurement(s) is/are considered normal PR intervals? Select all that apply.

1. 0.01 second
• Rationale:

This answer is not correct because a PR interval of 0.01 second is much too short and indicates an abnormal rhythm. Anxiety, stress and caffeine and cause a short interval. This finding should be reported to the healthcare provider. Normal sinus rhythm on the ECG is represented by PR interval measures 0.12 – 0.20 second, and the QRS complex measures 0.04 – 0.10 second.

2. 0.04 second
• Rationale:

This answer is not correct because a PR interval of 0.04 second is much too short and indicates an abnormal rhythm. Anxiety, stress and caffeine and cause a short interval. This finding should be reported to the healthcare provider. Normal sinus rhythm on the ECG is represented by PR interval measures 0.12 – 0.20 second, and the QRS complex measures 0.04 – 0.10 second.

3. 0.14 second
• Rationale:

This answer is correct because a PR interval of 0.14 second is considered normal. Normal sinus rhythm on the ECG is represented by PR interval measures 0.12 – 0.20 second, and the QRS complex measures 0.04 – 0.10 second.

4. 0.18 second
• Rationale:

This answer is correct because a PR interval of 0.14 second is considered normal. Normal sinus rhythm on the ECG is represented by PR interval measures 0.12 – 0.20 second, and the QRS complex measures 0.04 – 0.10 second.

5. 0.40 second
• Rationale:

This answer is not correct because a PR interval of 0.40 second is much too long and indicates an abnormal rhythm, such as a first degree atrioventricular block. This finding should be reported to the healthcare provider. Normal sinus rhythm on the ECG is represented by PR interval measures 0.12 – 0.20 second, and the QRS complex measures 0.04 – 0.10 second.

6. 0.60 second
• Rationale:

This answer is not correct because a PR interval of 0.60 second is much too long and indicates an abnormal rhythm, such as a first degree atrioventricular block. This finding should be reported to the healthcare provider. Normal sinus rhythm on the ECG is represented by PR interval measures 0.12 – 0.20 second, and the QRS complex measures 0.04 – 0.10 second.

### Overview

The normal PR interval of an ECG strip is 0.12-0.20 second.

### Learning Outcomes

An electrocardiogram (ECG) is a non-invasive cardiac test that uses electrodes on the body that reads and records the electrical signal from the heart. The information is available on the monitor screen and/or the print out of the ECG. Healthcare providers are trained to read the ECG strip and detect abnormalities in the rate and rhythm of the heart. Normal sinus rhythm consists of heart rate between 60 and 100 beats per minute with regular rhythm. Normal sinus rhythm on the ECG is represented by PR interval measures 0.12 – 0.20 second, and the QRS complex measures 0.04 – 0.10 second.

### Test Taking Tip

It is very important to know the normals of the ECG rhythms so abnormalities can be identified and reported.