Junctional Rhythms | Junctional Escape Rhythms | Junctional Tachycardia

Thomas E. O'Brien
AS CCT CRAT RMA

Learning Objectives

After completing this junctional rhythms module and its quiz, you will be able to:

  • Apply the 5-steps of heart rhythm interpretation
  • Recognize regular vs irregular rhythms
  • Remember the normal time interval range for PR interval and QRS complex
  • Recognize the features and qualifying criteria for these rhythms:
    • Premature Junctional Complexes
    • Junctional Escape Beats
    • Junctional Rhythm
    • Accelerated Junctional Rhythm
    • Junctional Tachycardia
    • Supraventricular Tachycardia

Course Progress Tracking

A quiz is available upon completion of this module's lessons.

Certificates of achievement are also available to registered users.


Authors and Reviewers

Authored by Thomas O'Brien.
Medically reviewed by Dr. Jonathan Keroes, MD, Cardiology.
Last Update: 2/4/2022





Rhythm Analysis Method

This module assumes that you have a good understanding of the 5-step EKG rhythm analysis method. Use the button below if you would like to read our lesson on 5-step rhythm analysis.

5-step Rhythm Analysis Lesson


How to Interpret Junctional Rhythms EKG

Introduction

  • The previous slides presented the five-steps of rhythm analysis. These five steps must be followed regardless of how simple of complex the tracing is you are reviewing.
  • The information gathered in these steps are telling a story.
  • The title of that story is the interpretation.

Junctional Dysrhythmias Background

  • The dysrhythmias in this category occur as a result of a problem where either the SA node fails to initiate the electrical impulse to begin the cardiac complex or the AV node rate of automaticity is firing faster than the SA node, and it takes over as the “pacemaker” of the heart.
  • This can happen for a number of reasons. Stress, fatigue, diet & disease are the chief culprits.

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Introduction I

  • Cardiac rhythms are typically named by the site of origin or heart structure where the problem is occurring
  • These junctional dysrhythmias primarily affect the P wave.
  • Electrical impulses formation and flow in a normal heart follow a forward or antegrade flow through the atria. This results in the upright P wave we see with Sinus rhythms.
  • With junctional rhythms, the impulse is initiated in the AV junction. This impulse point results in a backward or retrograde flow of electricity during atrial depolarization.
  • This change in the flow of electricity results in an inverted P wave. This morphologic feature is unique to Junctional complexes and rhythms.

Introduction II

P Wave & QRS Complex

  • The coordination of the P wave and QRS complex is also affected by the increased conduction velocity of the electrical impulses in the ventricular myocardium.
  • The inverted P wave may be seen before, or after the QRS complex, or it may be buried within it.
  • Refer to the image on the next slide to reinforce this concept.

Illustration

junctional ecg image 2

Intro to PJC

  • PJC's can occur for a number of different reasons i.e., diet, fatigue, stress, disease, ischemia to name a few.
  • Premature complexes frequently occur in bradycardic rhythms, but may occur almost any time.
  • PJC's occur when an early electrical impulse occurs from a location in the atria other than the SA node.

Types

We will be discussing the following complexes and rhythms:

  • Premature Junctional Complexes and Junctional
  • Escape Beats
  • Junctional Rhythm
  • Accelerated Junctional Rhythm
  • Junctional Tachycardia
  • Although not specifically a Junctional rhythm, we include supraventricular tachycardia because it may originate above the ventricles (including the junction).

Premature Junctional Complex (PJC) and Junctional Escape Beats

Part I

  • PJC’s and Escape Beats may occur for a number of different reasons i.e., diet, fatigue, stress, disease, ischemia
  • Premature complexes and Escape Beats frequently occur in bradycardic rhythms, but may occur almost any time.
  • Morphologically there is no difference between PJC’s and Escape Beats.

junctional ecg image 3

Part II

  • After reviewing the previous slide you should note that the difference is that PJC’s occur early and disrupt the underlying rhythm.
  • Escape beats typically occur when a cardiac rhythm is too slow and a backup pacemaker site initiates an electrical impulse.
  • It is fairly common that a Junctional Escape Beat will occur as the first complex to terminate Sinus Arrest

PJCs

  • This early impulse causes an early cardiac complex which disrupts the underlying rhythm.
  • The locus of stimulation being different, results in a change in the morphology of the P wave (inverted if it can be seen).
  • PJC’s can occur occasionally or frequently.
  • PJC’s can be observed with or without a pattern
  • The P wave with PJC’s may occur before or after the QRS complex or be buried within the QRS.

PJC Tracings

Example

Notice the following:
  • The R to R interval is irregular
  • The fourth complex is early
  • The P wave on the early complex is inverted.

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Practice Strip

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Analyze this tracing using the five steps of rhythm analysis.

Show Answer
  • Rhythm: Irregular
  • Rate: 70
  • P Wave: upright, early complex inverted
  • PR interval: 0.16 sec, early complex with shorter PR
  • QRS: 0.08 sec
  • Interpretation: Sinus Rhythm with PJC



Junctional Escape Beat

Practice Strip

junctional ecg image 7

Analyze this tracing using the five steps of rhythm analysis.

Show Answer
  • Rhythm: Irregular
  • Rate: 40
  • P Wave: upright, third complex inverted
  • PR interval: 0.16 sec, third complex with shorter PR
  • QRS: 0.08 sec
  • Interpretation: Sinus Arrest with Junctional Escape Complex



Junctional Rhythm

Junctional Rhythm

  • Rhythms are often named according to the origin of the electrical activity in the heart or the structure where the problem is occurring.
  • Junctional Rhythm aka Junctional “Escape” Rhythm is aptly named due to the electrical impulses causing the atrial activity are originating in the AV Junction.
  • The rate for this rhythm is the same as the AV Junction, 40 – 60 bpm.
  • The change in the locus of stimulation affects the morphology (inverted) and potential location of the P waves (before, during or after the QRS complex).
  • If the P wave occurs before the QRS, the PR interval will likely measure shorter than normal (0.12 second).
  • If the P wave is buried or occurs after the QRS, it cannot be measured.

Practice Strip

junctional ecg image 8

Analyze this tracing using the five steps of rhythm analysis.

Show Answer
  • Rhythm: Regular
  • Rate: 43
  • P wave: inverted
  • PR interval: 0.08 sec
  • QRS: 0.08 sec
  • Interpretation: Junctional Escape Rhythm



Accelerated Junctional Rhythm

Description

  • Accelerated junctional rhythm is just a faster version of junctional escape rhythm. The criteria is the same with the only difference being the heart rate range is 60 – 100 bpm.
  • Note the heart rate range. It is the same as the range for normal sinus rhythm.
  • When considering the heart is a pump and if everything else is functioning properly, we should expect a patient with accelerated junctional rhythm to display signs of normal cardiac output i.e. alert and oriented, normotensive, without apparent signs of distress.
junctional ecg image 12

Practice Strip

junctional ecg image 11

Analyze this tracing using the five steps of rhythm analysis.

Show Answer
  • Rhythm: Regular
  • Rate: 83
  • P wave: inverted
  • PR interval: 0.08 sec
  • QRS: 0.08 sec
  • Interpretation: Accelerated Junctional Rhythm


Junctional Tachycardia

Junctional Tachycardia

  • Junctional tachycardia occurs when a junctional rhythm exceeds 100 bpm.
  • Junctional tachycardia commonly ranges from 100 – 180 bpm.
  • All other criteria is the same.
junctional tachycardia tracing

Practice Strip

junctional tachycardia tracing #2

Analyze this tracing using the five steps of rhythm analysis.

Show Answer
  • Rhythm: Regular
  • Rate: 103
  • P wave: inverted
  • PR interval: 0.10 sec
  • QRS: 0.08 sec
  • Interpretation: Junctional Tachycardia


Supraventricular Tachycardia

Supraventricular Tachycardia

  • Supraventricular tachycardia occurs when the heart rhythm occurs as a result of electrical impulses initiated above the ventricles at a rate of 150 - 250 bpm or more.
  • What will remain will be a normal appearing and measuring QRS complex depolarizing at a rapid rate.
  • As a result of the rapid rate, the cardiac complexes will be very close to one another.
  • The T waves of the previous complex will cover the P wave of the next complex. P waves will be entirely buried making it impossible to describe their morphology and measure the PR interval.
junctional ecg image 13

Practice Strip

junctional ecg image 14

Analyze this tracing using the five steps of rhythm analysis.

Show Answer
  • Rhythm: Regular
  • Rate: 200
  • P wave: Buried
  • PR interval: Unable to measure
  • QRS: 0.06 sec
  • Interpretation: Supraventricular Tachycardia



Quiz

After you have completed the course materials, use the button below to take the course quiz. Scores of 70% and higher will be saved to your dashboard, provided that you are signed-in. And yes, you can retake the quiz without penalty. We keep your highest score.

Junctional Rhythms Course Quiz
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