Introducing the Junctional Rhythms

1. 9 Introducing the Junctional Rhythms

2. 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

3. 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

4. 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 thatpatient assessmentis the most important indicator of clinical significance

5. Components of Electrical Conduction System of the Heart • Electrical impulseoriginates inSA node • Travels through atriaviainternodal pathways • AV node,brief pause,bundle of His • Rightandleft bundle branches • Purkinje fibersinto the ventricular musculature

6. 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

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

8. 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?

9. 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

10. The Premature Junctional Contraction (PJC) • PJC can also cause compensatory pause, a pause that occurs after ectopic beat and underlying rhythm is uninterrupted

11. Premature Junctional Complexes

12. Premature Junctional Complexes

13. 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

14. 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 40-60 bpm

15. 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

16. Junctional Escape Beats

17. Junctional Escape Rhythm

18. 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

19. Accelerated Junctional Rhythm

20. Accelerated Junctional Rhythm

21. 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

22. Junctional Tachycardia Rhythms Junctional Tachycardia Rhythms • 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

23. Junctional Tachycardia

24. Junctional Tachycardia

25. 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

26. 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

27. 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

28. 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