How are you going to identify junctional beats?

• A. The QRS complex
• B. The T wave
• C. The P wave
• D. The PR interval

Answer: (C)

Identifying junctional beats hinges on how atrial activity relates to ventricular activity. When the impulse starts in the AV junction, atrial activation is often retrograde, so the P waves don’t follow the usual pattern seen with sinus beats. The telltale signs are P waves that are absent before the QRS, or that appear after the QRS—and in some cases they may be inverted or hidden within the QRS complex. This relationship between the P wave and the QRS is the key clue that the rhythm is driven from the AV junction rather than the atria. The QRS itself is typically normal in width, since ventricular conduction isn’t impaired, and the T wave can look normal too; the PR interval becomes unreliable or absent because the P wave timing is altered. So, looking for the presence, timing, or inversion of P waves relative to the QRS is the best way to identify junctional beats.