Introduction to Atrial Rhythms

Overview

ventricular rhythm heart illustration

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

Atrial rhythms originate in the atria rather than in the SA node. The P wave will be positive, but its shape can be different than a normal sinus rhythm because the electrical impulse follows a different path to the AV (atrioventricular) node. These EKG differences are covered on our atrial rhythms training module as well as in practice strips which are available via a link in the right column. Atrial rhythms are classified as:

  • Atrial Fibrillation (afib)
  • Atrial Flutter
  • Multifocal Atrial Tachycardia
  • Premature Atrial Complex
  • Supraventricular Tachycardia
  • Wandering Atrial Pacemaker
  • Wolff-Parkinson-White Syndrome

Sign Up or Sign In now. Unlock drills, quizzes and lessons.

SignUp

Atrial Rhythm Categories

Atrial Fibrillation

Atrial Fibrillation EKG tracing Irritable sites in the atria fire very rapidly, between 400-600 bpm. This very rapid pacemaking caused the atria to quiver. The ventricles beat at a slower rate due to the AV node's blocking of some of the atrial impulses.

Atrial Flutter

Atrial Flutter EKG tracing There are two types of atrial flutter. Type I (also called classical or typical) has a rate of 250-350 bpm. Type II (also called non-typical) are faster, ranging from 350-450 bpm. EKG tracings will show tightly spaced waves or saw-tooth waveforms (F-waves).

Multifocal Atrial Tachycardia

Multifocal Atrial Tachycardia EKG tracing When multifocal atrial tachycardia occurs, multiple (non-SA) sites are firing impulses. The P waves will vary in shape and at least three different shapes can be observed. The PR Interval varies. Ventricular rhythm is irregular.

Premature Atrial Complex

Premature Atrial Complex EKG tracing This occurs when an ectopic sites within the atria fires an impulse before the next impulse from the SA node. If the ectopic site is near the SA node, the P wave will likely have a shape similar to a sinus rhythm. But this P wave will occur earlier than expected.

Supraventricular Tachycardia

Supraventricular Tachycardia EKG tracing This term covers three types of tachycardia that originate in the atria, AV junction or SA node.

Wandering Atrial Pacemaker

 rhythm EKG tracing Wandering atrial pacemaker is an irregular rhythm. In is similar to multifocal atrial tachycardia but the heart rate is under 100 bpm. P waves are present but will vary in shape.

Wolff-Parkinson-White Syndrome

 rhythm EKG tracing This occurs when the impulse travels between the atria and ventricles via an abnormal path, called the bundle of Kent. The impulse, not being delayed by the AV node, can cause the ventricles to contract prematurely. EKG characteristics include a shorter PR Interval, longer QRS complex and a delta wave.
Click To Begin Atrial Rhythms Training Module

Overview

Atrial 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 Atrial Complexes
    • Wandering Atrial Pacemaker Rhythm
    • Multifocal Atrial Tachycardia
    • Atrial Flutter
    • Atrial Fibrillation

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.

Atrial Dysrhythmias Types

The dysrhythmias in this category occur as a result of problems in the atria. These atrial dysrhythmias primarily affect the P wave. We will be discussing the following complexes and rhythms:

  • Premature Atrial Complexes (PAC’s)
  • Wandering Atrial Pacemaker
  • Multifocal Atrial Tachycardia
  • Atrial Flutter
  • Atrial Fibrillation

Premature Atrial Complex

Intro to PAC

  • PAC'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.
  • PAC's occur when an early electrical impulse occurs from a location in the atria other than the SA node.

Intro to PAC 2

  • 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.
  • PAC's can occur occasionally or frequently.
  • PAC's can be observed with or without a pattern
  • The P wave with PAC's will always be upright

EKG Analysis

atrial ecg image

Notice the following: the R to R interval is irregular, the fifth complex is early and the P wave on the early complex is a different shape.

EKG Practice Strip

atrial ecg image 2
  • Analyze this tracing using the five steps of rhythm analysis.
  • Compare your answers with the answers on the next slide.

Answer

atrial ecg image 3
  • Rhythm: Irregular
  • Rate: 50
  • P wave: Upright & uniform (except early complexes - biphasic)
  • PR interval: 0.16 second
  • QRS: 0.08
  • Interpretation: Sinus Bradycardia with PAC's

Wandering Atrial Pacemaker

Description

  • Rhythms are often named according to the origin of the electrical activity in the heart or the structure where the problem is occurring.
  • Wandering Atrial Pacemaker is aptly named due to the electrical impulses causing the atrial activity are moving or wandering.
  • These changes in the locus of stimulation affect the morphology of the P waves.

Analysis

    wandering atrial pacemaker tracing
  • In Wandering Atrial Pacemaker, you must observe at least three different shaped P waves. No other changes in the tracing may be observed. The rhythm may or may not be regular.
  • The PR interval is often affected, but does not have to be.
  • The bottom line, is you must observe at least three different shaped P waves.

Practice Strip

Wandering Atrial Pacemaker - Practice Strip

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

Answers

Wandering Atrial Pacemaker - Practice Strip - Answers

wandering atrial pacemaker tracing
  • Rhythm: Irregular
  • Rate: 50
  • P wave: Changing Shapes (3 or more)
  • PR interval: Variable
  • QRS: 0.08
  • Interpretation: Wandering Atrial Pacemaker

Multifocal Atrial Tachycardia

Multifocal Atrial Tachycardia

  • Multifocal Atrial Tachycardia is just a faster version of Wandering Atrial Pacemaker. The criteria is the same as Wandering Atrial Pacemaker with the only difference being the heart rate exceeds 100 bpm.
  • These changes in the locus of stimulation within the atria affect the morphology of the P waves.
  • Remember, you must observe at least three different shaped P waves.
  • Due to the presence of irregular R to R intervals coupled with the changing P wave morphology, some people have confused this rhythm with Atrial Fibrillation.

Atrial Flutter

Description

  • Atrial Flutter occurs when there is an obstruction within the atrial electrical conduction system.
  • Due to this impediment a series of rapid depolarizations occur.
  • These depolarizations may occur two, three, four or more times per QRS complex.
  • The AV node functions like a “gate keeper” blocking the extra impulses until the ventricular conduction system is able to accept the impulse.
  • The impulse that is accepted will cause the QRS complex to occur.

Analysis

atrial flutter tracing
  • Each flutter wave represents atrial depolarization. This will be noted next to the P wave step in rhythm analysis. Instead of P waves, this tracing has “F” waves. No P waves mean there is no PR interval measurement.
  • When the tracing is interpreted, the ratio of F waves to each QRS complex will be documented along with the rhythm i.e. Atrial Flutter 4:1 (indicates 4 “F” waves to each QRS complex). Not all Atrial Flutter will have a regular rhythm. In that case just document and report your observations.

Practice Strip

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

Practice Strip Answers

atrial flutter ekg
  • Rhythm: Regular
  • Rate: Ventricles - 80, Atria - 320
  • P wave: "F" waves
  • PR interval: absent
  • QRS: 0.08
  • Interpretation: Atrial Flutter 4:1

Atrial Fibrillation

Description

  • Atrial Fibrillation occurs when multiple electrical impulses occur within within the atria. This chaotic electrical activity results in a chaotic wave form between the QRS complexes. P waves are absent. They are replaced by lower case "f" waves. No P waves means there is no PR interval measurement.
  • This rapid electrical activity overwhelms the AV node causing impulses to enter the ventricular conduction system at irregular points. This results in irregular R to R intervals.

Analysis

  • Not all fibrillatory waves are created equal. The "f" waves can be coarse (majority measure 3 mm or more) or can be fine (majority of waveforms measure less than 3 mm) to almost absent. Regardless always report your observations. Many times when a patient has "new onset" Atrial Fibrillation the patient will report with a heart rate of 160 bpm or more.

Mechanisms

  • When a patient experiences A-fib, the atria are not contracting as they normally would. They are just quivering. This absence of contraction of the atria can result in a loss of cardiac output anywhere from 15 - 30% due to the absence of "atrial kick". This is why the heart rate is so high. The body is trying to maintain homeostasis.
  • It will be impossible to determine the atrial rate. You will only be able to analyze and report the ventricular rate.
  • Atrial Fibrillation with a ventricular response in excess of 100 bpm is commonly referred to as Atrial Fibrillation with “rapid ventricular response” or "uncontrolled A-fib".
atrial fibrillation tracing

Practice Strip

Atrial Fibrillation - Practice Strip

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

Answers

Atrial Fibrillation - Practice Strip - Answers

atrial fibrillation ekg
  • Rhythm: Irregular
  • Rate: Ventricles - 90, Atria - Unable to determine (UTD)
  • P wave: "f" waves
  • PR interval: absent
  • QRS: 0.08
  • Interpretation: Atrial Fibrillation

Test Questions 1-5

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. Phase 0 analysis
D. QRS complex measurement




Question #3

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

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 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 #5

Which feature is most closely associated with Wandering Atrial Pacemaker rhythm?

A. Wide & bizarre QRS complexes
B. PR interval measuring greater than 0.20 seconds
C. Pronged QT interval
D. Three or more different shaped P waves





Test Questions 6-9

Question #6

Which feature is most closely associated with Atrial Fibrillation?

A. Lower case "f" waves
B. Upper case "F" waves
C. Inverted P waves
D. Heart rate less than 60 bpm




Question #7

Which feature is most closely associated with Atrial Flutter?

A. Lower case "f" waves
B. Upper case "F" waves
C. Inverted P waves
D. Heart rate less than 60 bpm




Question #8

In addition to Premature Atrial Complexes being an early cardiac complex in a rhythm strip; which morphologic feature most closely identifies this complex as being atrial 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




Question #9

Which rhythm is Multifocal Atrial tachycardia most often confused with?

A. Supraventricular Tachycardia
B. Atrial Flutter
C. Atrial Fibrillation
D. Wolfe Parkinson White Syndrome





Test Questions 10-14

Question #10

atrial quiz tracing

Select the heart rate most closely associated with this tracing.

A. 50
B. 70
C. 90
D. 110




Question #11

atrial quiz tracing

What is the most correct interpretation of this tracing?

A. Sinus Rhythm with PAC
B. Atrial Flutter
C. Wandering Atrial Pacemaker
D, Atrial Fibrillation




Question #12

atrial quiz tracing

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

A. Inverted
B. Absent
C. Variable (three or more)
D. Biphasic




Question #13

atrial quiz tracing

What is the most correct interpretation of this tracing?

A. Sinus Rhythm with PAC
B. Atrial Flutter
C. Wandering Atrial Pacemaker
D. Atrial Fibrillation




Question #14

atrial quiz tracing

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

A. Constant
B. Regularly irregular
C. Variable
D. All answers are incorrect





Test Questions 15-18

Question #15

atrial fibrillation ekg

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

A. Inverted
B. Absent
C. "f" waves
D. "F" waves




Question #16

atrial fibrillation ekg

Select the number that most closely represents the ventricular rate.

A. 65
B. 79
C. 264
D. 316




Question #17

atrial fibrillation ekg

Select the number that most closely represents the atrial rate.

A. 65
B. 79
C. 264
D. 316




Question #18

atrial fibrillation ekg

What is the most correct interpretation of this tracing?

A. Sinus Rhythm with PAC’s 4:1
B. Atrial Flutter 4:1
C. Wandering Atrial Pacemaker 4:1
D. Atrial Fibrillation 4:1





Test Questions 19-22

Question #19

atrial fibrillation ekg

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

A. Inverted
B. Absent
C. "f" waves
D. "F" waves




Question #20

atrial fibrillation ekg

Select the number that most closely represents the heart rate.

A. 75
B. 110
C. 130
D. 150




Question #21

atrial fibrillation ekg

What is the PR interval measurement

A. 0.06 seconds
B. 0.12 seconds
C. Variable
D. Absent, due to lack of P waves




Question #22

atrial fibrillation ekg

What is the most correct interpretation of this tracing?

A. Sinus Rhythm with PAC’s
B. Atrial Flutter with rapid ventricular response
C. Multifocal Atrial Tachycardia
D. Atrial Fibrillation with rapid ventricular response





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 »