Introduction to Junctional Rhythms

Overview

This page provides an introduction to junctional rhythms and links to training materials on this website.

The SA node is the normal origin of the electrical impulse for a heart beat. When the SA node cannot perform this role, the atrioventricular (AV) node may take-over pacemaking. When this occurs, the EKG will likely have distinctive waveform features that reveal important aspects of these junctional rhythms.

Junctional rhythms include:

  • Accelerated Junctional Rhythm
  • Junctional Escape Rhythm
  • Junctional Tachycardia
  • Premature Junctional Complex

Junctional Rhythm Categories

Accelerated Junctional Rhythm

Accelerated Junctional Rhythm EKG tracing Accelerated junctional rhythm occurs when the AV junction fires impulses at above 60 bpm. Rhythm will be very regular. The QRS complex is narrow (0.10 sec or less).

Junctional Escape Rhythm

Junctional Escape rhythm EKG tracing Junctional escape beats originate in the AV junction and are late in timing. They often occur during sinus arrest or after premature atrial complexes. The QRS complex will be measured at 0.10 sec or less. Rhythm will be regular with a rate of 40-60 bpm.

Junctional Tachycardia

Junctional Tachycardia EKG tracing This abnormal rhythm originates in the bundle of His. It is observed as three or more premature junctional complexes (PJCs) appearing in a row. Heart rate will be over 100 bpm.

Premature Junctional Complex

Premature Junctional Complex EKG tracing Premature junctional complex (PJC) occurs when an irritable site within the AV node fires an impulse before the SA node. This impulse interrupts the sinus rhythm. The QRS complex will be narrow, usually measured at 0.10 sec or less.
Click To Begin Junctional Rhythms Training Module

Overview

Junctional Dysrhythmias

Thomas E. O'Brien
AS CCT CRAT RMA

Learning Objectives

At the conclusion of this training module the reader will be able to:

  • Recall and apply the 5-steps of heart rhythm interpretation
  • Recognize the difference between regular and irregular rhythms
  • Recall the normal range for PR interval and QRS complex
  • Recognize the features and qualifying criteria for the following complexes and rhythms:
    • Premature Junctional Complexes
    • Junctional Escape Beats
    • Junctional Rhythm
    • Accelerated Junctional Rhythm
    • Junctional Tachycardia
    • Supraventricular Tachycardia

Using This Presentation

how to use this presentation image

Interpretation

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.

Introduction Part 1

Introduction

  • 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.

Inverted P Wave

  • The result of this retrograde depolarization is the classic inverted P wave.
  • Because the electrical impulse causing atrial depolarization may come from anywhere in the AV junction. This can affect the location or coordination with the QRS complex.
junctional ecg image

Introduction Part 2

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.

“ecg

Practice Strip

  • Analyze this tracing using the five steps of rhythm analysis.
  • Compare your answers with the answers on the next slide.

“ecg

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
“ecg

Junctional Escape Beat

Practice Strip

  • Analyze this tracing using the five steps of rhythm analysis.
  • T Compare your answers with the answers on the next slide.
junctional ecg image 7

Answers

  • 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 ecg image 6

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

  • Analyze this tracing using the five steps of rhythm analysis.
  • T Compare your answers with the answers on the next slide.
junctional ecg image 8

Answers

  • Rhythm: Regular
  • Rate: 43
  • P wave: inverted
  • PR interval: 0.08 sec
  • QRS: 0.08 sec
  • Interpretation: Junctional Escape Rhythm
junctional ecg image 9

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

  • Analyze this tracing using the five steps of rhythm analysis.
  • Compare your answers with the answers on the next slide.
junctional ecg image 11

Answers

  • Rhythm: Regular
  • Rate: 83
  • P wave: inverted
  • PR interval: 0.08 sec
  • QRS: 0.08 sec
  • Interpretation: Accelerated Junctional Rhythm
junctional ecg image 10

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

  • Analyze this tracing using the five steps of rhythm analysis.
  • Compare your answers with the answers on the next slide.
junctional tachycardia tracing #2

Answers

  • Rhythm: Regular
  • Rate: 103
  • P wave: inverted
  • PR interval: 0.10 sec
  • QRS: 0.08 sec
  • Interpretation: Junctional Tachycardia
junctional tachycardia tracing #2

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

  • Analyze this tracing using the five steps of rhythm analysis.
  • Compare your answers with the answers on the next slide.
junctional ecg image 14

Answers

  • Rhythm: Regular
  • Rate: 200
  • P wave: Buried
  • PR interval: Unable to measure
  • QRS: 0.06 sec
  • Interpretation: Supraventricular Tachycardia
junctional ecg image 15

Test Questions 1-4

Question #1

When analyzing a rhythm strip, it qualifies as being regular when

A. the QT intervals are the same
B. the PR interval measures the same
C. the QRS complexes measures the same
D. the R - R intervals measure the same




Question #2

Which of the following steps is not one of the five-steps of rhythm analysis?

A. PR interval measurement
B. Rhythm regularity
C. QT Interval
D. QRS complex measurement




Question #3

Which of the following is considered normal range of the QRS complex?

A. 0.12 - 0.20 minutes
B. 0.06 - 0.10 minutes
C. 0.12 - 0.20 seconds
D. 0.06 - 0.10 seconds




Question #4

Which of the following is considered normal range of the PR interval?

A. 0.12 - 0.20 seconds
B. 0.06 - 0.10 minutes
C. 0.12 - 0.20 minutes
D. 0.06 - 0.10 seconds





Test Questions 5-8

Question #5

Which feature is most closely associated with junctional complexes and rhythms?

A. Wide & bizarre QRS complexes
B. PR interval measuring greater than 0.20 seconds
C. Pronged QT interval
D. Inverted or buried P waves




Question #6

Which heart rate is most closely associated with junctional escape rhythm

A. 40 – 60 bpm
B. 60 - 100 bpm
C. 100 - 180 bpm
D. all responses are incorrect




Question #7

Which feature is most closely associated with junctional escape beats?

A. Lower case “f” waves, wide QRS complex
B. Complex with inverted P wave that may occur as the first complex terminating sinus arrest
C. Inverted P wave on a complex that occurs sooner than it is anticipated
D. Heart rate greater than 100 bpm




Question #8

In addition to premature junctional complexes being an early cardiac complex in a rhythm strip; which morphologic feature most closely identifies this complex as being junctional rather than another locus of stimulation?

A. At least a portion of the P wave is positively deflected
B. P waves are inverted or buried
C. QRS complex measures greater than 0.10 second
D. PR interval presents in a prolonging repetitious pattern





Test Questions 9-11

Question #9

Which heart rate range is most closely associated with supraventricular tachycardia?

A. 40 - 60
B. 60 - 100
C. 100 - 180
D. 150 - 250




Question #10

Select the heart rate most closely associated with this tracing.

ekg junctional quiz tracing
A. 90
B. 125
C. 200
D. 350




Question #11

What is the most correct interpretation of this tracing?

ekg junctional quiz tracing
A. Supraventricular Tachycardia
B. Atrial Flutter
C. Wandering Atrial Pacemaker
D. Atrial Fibrillation





Test Questions 12-14

Question #12

What would be the most proper description of the atrial activity in this tracing?

ekg junctional quiz tracing 12
A. Inverted
B. Absent
C. Variable (three or more)
D. Biphasic




Question #13

What is the most correct interpretation of this tracing?

ekg junctional quiz tracing 12
A. Junctional Escape Rhythm
B. Accelerated Junctional Rhythm
C. Junctional Tachycardia
D. Supraventricular Tachycardia




Question #14

Which term is most appropriately used to describe the PR interval in this tracing?

ekg junctional quiz tracing 12
A. Prolonged, greater than 0.20 sec
B. Regularly irregular
C. Short, less than 0.12 sec
D. All answers are incorrect





Test Questions 15-18

Question #15

What would be the most proper description of the atrial activity in this tracing?

ekg junctional quiz tracing 15
A. Inverted
B. Buried
C. “f” waves
D. “F” waves




Question #16

Select the number that most closely represents the ventricular rate.

ekg junctional quiz tracing 15
A. 65
B. 129
C. 200
D. 316




Question #17

What is the QRS complex duration measurement?

ekg junctional quiz tracing 15
A. Unable to measure
B. 0.06 sec
C. 0.14 sec
D.0.20 sec




Question #18

What is the most correct interpretation of this tracing?

ekg junctional quiz tracing 15
A. Sinus Tachycardia with PJC’s
B. Supraventricular Tachycardia
C. Wandering Atrial Pacemaker
D. Atrial Fibrillation





Test Questions 19-22

Question #19

What would be the most proper description of the atrial activity in this tracing?

ekg junctional quiz tracing 19
A. Inverted
B. Absent
C. “f” waves
D. “F” waves




Question #20

Select the number that most closely represents the heart rate.

ekg junctional quiz tracing 19
A. 75
B. 103
C. 130
D. 150




Question #21

What is the PR interval measurement?

ekg junctional quiz tracing 21
A. 0.08 seconds
B. 0.14 seconds
C. Variable
D. Absent, due to lack of P waves




Question #22

What is the most correct interpretation of this tracing?

ekg junctional quiz tracing 22
A. Sinus Rhythm with PJC
B. Junctional Escape Rhythm
C. Accelerated Junctional Rhythm
D. Junctional Tachycardia





EKG Self Test

EKG Rhythms Self Test

If you would like to tests the knowledge and skills learned in this module, use our EKG Rhythms Self Test. You can choose to focus this self-test on any of all of the following:

  • Sinus Mechanisms
  • Atrial Rhythms
  • Junctional Rhythms
  • Ventricular Rhythms
  • Atrioventricular Blocks
  • Pacemaker Rhythms

EKG Rhythm Tests »

Training Resources

Junctional Rhythm Training

A good starting point for learning is our junctional rhythms module. This module focuses on the morphologic features and qualifying criteria of junctional rhythms. A concise summary of a five step EKG analysis methodology is also included.

Junctional Rhythms

EKG Rhythm Tests

Hundreds heart rhythms in this practice test. Test can be tailored for specific learning needs.

EKG Rhythm Tests


External References

Wikipedia
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