Junctional Rhythm Analysis Flashcards

A rhythm analysis technician is reviewing a 6-second strip that shows a regular rhythm with a heart rate of 50 bpm. P waves are not discernible, and the QRS complexes are narrow, measuring 0.08 seconds. Which rhythm should the technician identify?

Answer: Junctional Rhythm

This rhythm is identified as a Junctional Rhythm (or Junctional Escape Rhythm) because the heart rate is between 40-60 bpm, which is the intrinsic rate of the AV junction. The absence of P waves and the presence of a narrow QRS complex are classic indicators that the impulse is originating from the AV junction and traveling down the normal ventricular conduction pathway.

Which of the following ECG findings is the most definitive characteristic of a rhythm originating from the AV junction?

Answer: An inverted or absent P wave with a short PR interval if visible

Rhythms originating in the AV junction cause retrograde (backward) depolarization of the atria. This results in P waves that are inverted in leads II, III, and aVF, or are absent because they are buried within the QRS complex. If a P wave precedes the QRS, the PR interval is short (<0.12 seconds) because the impulse has less distance to travel to the ventricles.

A CRAT observes a regular rhythm on a patient's monitor with a rate of 75 bpm. The QRS complexes are 0.06 seconds wide. There are inverted P waves in lead II just before each QRS complex, with a PR interval of 0.10 seconds. What is the correct interpretation of this rhythm?

Answer: Accelerated Junctional Rhythm

This rhythm is an Accelerated Junctional Rhythm. The rate of 61-100 bpm is faster than the intrinsic rate of the AV junction but slower than tachycardia. The presence of inverted P waves with a short PR interval confirms the junctional origin. Junctional Escape Rhythm is slower (40-60 bpm), and Junctional Tachycardia is faster (>100 bpm).

What is the intrinsic pacemaker rate of the atrioventricular (AV) junction?

Answer: 40-60 bpm

The AV junction, which includes the AV node and the bundle of His, has an intrinsic pacemaker rate of 40-60 beats per minute. It serves as a secondary pacemaker, taking over if the primary pacemaker, the SA node (60-100 bpm), fails.

A patient's ECG shows a regular, narrow-complex rhythm at a rate of 120 bpm. No P waves are visible before, during, or after the QRS complexes. This rhythm is best described as:

Answer: Junctional Tachycardia

This rhythm is Junctional Tachycardia. The rate is greater than 100 bpm, the QRS is narrow, and there are no visible P waves, which are characteristic findings. The AV junction has overridden the SA node due to enhanced automaticity, firing at a rate above 100 bpm.

All of the following are potential P wave presentations in a junctional rhythm EXCEPT:

Answer: Upright and uniform before each QRS with a PR interval of 0.16 seconds

An upright, uniform P wave with a normal PR interval (0.12-0.20 seconds) is the hallmark of a sinus rhythm, originating from the SA node. In a junctional rhythm, the P wave, if visible, results from retrograde atrial activation and will be inverted in the inferior leads and may appear before, during (hidden), or after the QRS complex.