If a PJB depolarizes the atria in a retrograde manner, what will be observed on an EKG?

If a PJB depolarizes the atria in a retrograde manner, what will be observed on an EKG?

• A. Upright P waves
• B. Inverted P waves
• C. Bizarre QRS complexes
• D. Flatline segments

Answer: (B)

When a junctional beat initiates depolarization in a retrograde manner, it stimulates the atria from the bottom up, which is opposite to the normal depolarization process that occurs from the sinoatrial (SA) node downwards. As a result, the P waves observed on the EKG will be inverted. This is because the electrical activity of the atria is moving away from the positive electrode of the lead being monitored, which causes the tracing to reflect this activity as downward or negative deflections.

In cases where P waves appear upright, it generally indicates depolarization originating from the SA node or in the normal direction. Bizarre QRS complexes suggest an issue with ventricular conduction rather than retrograde atrial depolarization. Flatline segments would imply a lack of electrical activity or severe interruptions in conduction, which do not correlate with retrograde atrial depolarization. The presence of inverted P waves distinctly shows the effect of retrograde conduction on the EKG tracing.