Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley For the Dental Hygienist CHAPTER Understanding EKGs A Practical Approach 9 Introducing the Junctional Rhythms

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Introducing Junctional Rhythms Objectives –Discuss the origin of junctional rhythms –Recall the components of the electrical conduction system –Identify premature junctional contractions, including EKG characteristics –Identify a junctional escape rhythm, including EKG characteristics

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Introducing Junctional Rhythms Objectives (continued) –Identify an accelerated junctional rhythm, including EKG characteristics –Identify a junctional tachycardia rhythm, including EKG characteristics –Discuss the clinical significance of the junctional rhythms

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Origin of Junctional Rhythms Rhythms that are initiated in the area of the AV junction are called junctional rhythms Although junctional rhythms are not considered to be lethal, or life-threatening, you should recall that patient assessment is the most important indicator of clinical significance

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Components of Electrical Conduction System of the Heart Electrical impulse originates in SA node Travels through atria via internodal pathways AV node, brief pause, bundle of His Right and left bundle branches Purkinje fibers into the ventricular musculature

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley P Waves in Junctional Rhythms Normally P waves are seen before each QRS Impulse in junctional rhythm is traveling away from (+) electrodes, P wave will be inverted or negative The P wave can be hidden in the QRS or follow the QRS complex

Impulse Direction The location of the impulse changes the position of the ‘P’ wave

Impulse originates in AV Node and retrograde backward to SA Node Causing a negative deflection on ECG of ______ Wave? The impulse will follow normal route and ______ wave will be _______ deflected on the ECG?

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley The Premature Junctional Contraction (PJC) Are initiated from a single site in the AV junction and arise earlier than the next anticipated complex of the underlying rhythm If SA node depolarized by ectopic beat, a noncompensatory pause occurs and underlying rhythm is interrupted

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley The Premature Junctional Contraction (PJC) PJC can also cause compensatory pause, a pause that occurs after ectopic beat and underlying rhythm is uninterrupted

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Premature Junctional Complexes

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Premature Junctional Complexes

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Premature Junctional Contraction (Complexes) or PJCs PJCs are less common than PACs or PVCs As with all ectopic beats, it is easier to identify PJCs if rhythm is sinus or bradycardia When interpreting PJCs, you must also determine the underlying rhythm

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Junctional Escape Rhythms The SA node may fail to generate an impulse, or if rate falls below that of the AV node, then AV node will assume the role of pacemaker This ability is a safety feature Intrinsic rate of the AV node is bpm

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Junctional Escape Rhythm Junctional escape beat –Isolated junctional beat occurs Junctional escape rhythm –Series of junctional escape beats occur, (sometimes termed junctional bradycardia when rate < 40 bpm Causes –SA node disease, hypoxia, increased parasympathetic (vagal) tone, cardiac drugs, or complete heart block

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Junctional Escape Beats

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Junctional Escape Rhythm

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Accelerated Junctional Rhythms Caused by increased automaticity in AV junction, causes junction to discharge impulses at fast rate, then intrinsic rate (40-60 bpm) Rate is usually around 60 to 100 bpm Causes include –Hypoxia, digitalis intoxication, inferior wall MI, and rheumatic fever

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Accelerated Junctional Rhythm

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Accelerated Junctional Rhythm

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Junctional Tachycardia Rhythms Rhythm that arises from AV junctional tissue at a rate of 100 to 180 bpm If observed to start or end abruptly referred to as paroxysmal rhythm It may be indistinguishable from supraventricular tachycardic rhythms

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Causes –Underlying ischemic heart disease, frequent ingestion of stimulants, anxiety, hypoxia, Medications such as digitalis, or rheumatic heart disease Treatment –Aimed at identifying and treating the underlying cause of the dysrhythmia Junctional Tachycardia Rhythms

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Junctional Tachycardia

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Junctional Tachycardia

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Clinical Significance of Junctional Rhythms Premature Junctional Contractions –Based on frequency of their occurrence and patient’s condition –Isolated PJCs are of minimal significance –Frequent (> than 6/min) more serious dysrhythmias may develop –Management includes only close observation

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Clinical Significance of Junctional Rhythms Junctional Escape Rhythm –Based on patient’s heart rate and clinical condition –Intrinsic rate of AV junction = 40 to 60 bpm –Watch for signs of compromise –If decreased perfusion observed, treat with oxygen, and consider drug therapy –May be tolerated at 50 to 60 bpm

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Clinical Significance of Junctional Rhythms Accelerated Junctional Rhythm –Generally well tolerated by patient –May suggest the possibility of digitalis toxicity –Patient must be carefully monitored for occurrence of other, more serious dysrhythmias

Copyright ©2010 by Pearson Education, Inc. Upper Saddle River, New Jersey All rights reserved. Understanding EKGs: A Practical Approach, Third Edition Brenda M. Beasley Clinical Significance of Junctional Rhythms Junctional Tachycardia Rhythm –May be well tolerated in healthy hearts –Not tolerated in patients with cardiac compromise –May report feeling heart “running away or fluttering” –Treatment based on patient’s clinical appearance, signs, and symptoms