ECG Question #15


A nurse caring for a client on telemetry interprets the electrocardiogram (ECG) as having a bundle branch block based on the following characteristics:


  1. A narrow QRS segment
    • Rationale:
  2. A wide QRS segment
    • Rationale:
  3. An inverted PR interval
    • Rationale:
  4. A spiked PR interval
    • Rationale:



Bundle branch block occurs when an impulse is blocked as it travels through the bundle branches. Electrical impulses travel down the right and left bundle branches at the same speed. A block in one of the branches causes the electrical impulse to travel to the ventricle via an alternate route. The ventricle still contracts; however, it will take longer and the impulse will be slower. One ventricle contracts a fraction of a second slower than the other ventricle. Blocks can be either right or left. A bundle branch block does not cause a narrow QRS segment, an inverted PR interval, or a spiked PR interval.

Learning Outcomes

Test Taking Tip

Video Rationale