8/20/2012. Learning Outcomes (Cont d)

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1 Electrocardiography for Healthcare Professionals Chapter 7: Junctional Dysrhythmias Learning Outcomes 7.1 Describe the various junctional dysrhythmias 7.2 Identify premature junctional complexes using the criteria for classification, and explain how the rhythm may affect the patient, including basic patient care and treatment. Learning Outcomes (Cont d) 7.3 Identify junctional escape rhythm using the criteria for classification, and explain how the rhythm may affect the patient, including basic patient care and treatment. 7.4 Identify accelerated junctional rhythm using the criteria for classification, and explain how the rhythm may affect the patient, including basic patient care and treatment. Learning Outcomes (Cont d) 7.5 Identify junctional tachycardia rhythm using the criteria for classification, and explain how the rhythm may affect the patient, including basic patient care and treatment. 7.6 Identify supraventricular tachycardia rhythm using the criteria for classification, and explain how the rhythm may affect the patient, including basic patient care and treatment Introduction to Junctional Dysrhythmias Results from electrical impulses coming from the AV node rather than SA node Inherent rate of AV node is 40 to 60 beats per minute Inverted P wave is seen in junctional dysrhythmias 7.1 Introduction to Junctional Dysrhythmias (Cont d) AV node is the backup pacemaker for the heart if the SA node has been injured and results in: Junctional rhythm Accelerated junctional rhythm Junctional tachycardia 7 8 What causes the inverted P wave found with junctional rhythms? What causes the inverted P wave found with junctional rhythms? Answer: Electrical impulses are coming from the AV node causing depolarization of the atria to flow retrograde. This reverse flow causes the inverted P wave. 9 What is the inherent rate of the AV node? 1

2 10 What is the inherent rate of the AV node? 11 ANSWER: 40 to 60 beats per minute 7.2 Premature Junctional Complex (PJC) Criteria An early electrical impulse that originates from the AV junction Rhythm may be irregular Rate will depend on the underlying rhythm Premature Junctional Complex P wave of the early beat may be inverted, and may proceed, follow, or be buried in the QRS complex PR interval may be shorter than normal or absent QRS duration will be second Premature Junctional Complex Isolated PJCs cause no signs or symptoms in healthy patients Patients may experience hypotension (low blood pressure) and low cardiac output if PJCs occur more than four to six times per minute 7.2 Apply Your Knowledge What is unique about Premature Junctional Complexes? 7.2 Apply Your Knowledge What is unique about Premature Junctional Complexes? Answer: PJC s have an irregular rhythm and the P wave is inverted and may appear before, during or after the QRS complex Originates at AV junctional tissue Produces retrograde depolarization of atrial tissue Stimulates depolarization of ventricles Criteria Rhythm P-P and R-R intervals are regular and have similar intervals P-P interval may be difficult to determine due to location of P wave Rate 40 to 60 beats per minute 2

3 P wave configuration Usually inverted May follow, precede, be within QRS complex, or not be visible PR interval if before the QRS complex, will be less than 0.12 second and be constant; otherwise cannot be determined QRS duration second Slower heart rate can lead to low cardiac output, leading to hypotension, confusion, or disorientation Report junctional escape rhythm to a licensed practitioner for treatment 7.3 Apply Your Knowledge What is unique about Junctional Escape Rhythm? 7.3 Apply Your Knowledge What is unique about Junctional Escape Rhythm? Answer: The P wave may occur before, during, or after the QRS complex. If the P wave is seen, it will be inverted Originates at AV junctional tissue Produces retrograde (backward) depolarization of atrial tissue Stimulates the depolarization of ventricles Criteria Rhythm the P-P and R-R intervals are regular and similar the P-P interval may be difficult to measure due to location of the P wave Rate 60 to 100 beats per minute P wave configuration usually inverted may precede, follow, or fall within QRS complex may not be visible at all on rhythm strip PR interval if before the QRS complex, will be less than 0.12 second and be constant; otherwise cannot be determined QRS duration 3

4 second 26 May have inverted or absent P wave or P wave that follows QRS complex Unlikely patient will show signs of low cardiac output Report accelerated junctional rhythm to a licensed practitioner for treatment Apply Your Knowledge What is unique about Accelerated Junctional Rhythm? 7.4 Apply Your Knowledge What is unique about Accelerated Junctional Rhythm? Answer: This rhythm may have an inverted or absent P wave, or one that follows the QRS complex. Heart rate is between 60 and 100 bpm. 29 Heart rate is faster Originates at AV junctional tissue Produces retrograde (backward) depolarization of atrial tissue Stimulates the depolarization of ventricles Criteria Rhythm P-P and R-R intervals are regular and similar P-P may be difficult to measure due to location and increased heart rate Rate 100 to 150 beats per minute P wave configuration usually inverted may precede, follow, or fall within the QRS complex may not be visible on rhythm strip may need to increase paper speed on cardiac monitor PR interval if before the QRS complex, will be less than 0.12 second and be constant; otherwise cannot be determined QRS duration second 4

5 Patient may complain of palpatations or heart fluttering with faster rates Considered very serious or life threatening after a recent MI Report junctional tachycardia rhythm to a licensed practitioner for treatment 7.5 Apply Your Knowledge What is unique about Junctional Tachycardia Rhythm? 7.5 Apply Your Knowledge What is unique about Junctional Tachycardia Rhythm? Answer: This rhythm may have an inverted or absent P wave, or one that follows the QRS complex. Heart rate is between 100 and 150 bpm Supraventricular Tachycardia Rhythm (SVT) Rapid heart beat makes identification of origin difficult Will originate from the atria or junction 7.6 Supraventricular Tachycardia Rhythm (SVT) Criteria Rhythm R-R usually regular If identifiable, P waves usually regular Rate Ventricular rate is beats per minute Atrial rate is difficult to determine 7.6 Supraventricular Tachycardia (SVT) P wave configuration Usually not identifiable at this heart rate, since P wave may lie inside T wave P wave may occur before, during, or after QRS complex PR interval usually unable to determine QRS duration seconds 7.6 Supraventricular Tachycardia Rhythm Patient may be in stable or unstable condition Observe patient for low cardiac output Notify licensed practitioner and begin treatment as early as possible 7.6 Apply Your Knowledge Where in the heart does a supraventricular tachycardia originate? 5

6 Apply Your Knowledge Where in the heart does a supraventricular tachycardia originate? 42 ANSWER: Either the atria or AV junction of the heart Law and Ethics Evaluating rhythm strips and assessing patients beyond the scope of your practice is illegal Chapter Summary Junctional rhythms impulses come from AV node or junction the impulses causing depolarization of the atria are flowing retrograde causes inverted P waves AV node is functioning as pacemaker for the heart due to injury of the SA node Chapter Summary (Cont d) Premature junctional complex (PJC) is a single, early impulse that originates in the AV junction occurs before the next sinus impulse Junctional escape rhythm originates at AV junction produces retrograde depolarization stimulates depolarization of ventricles Chapter Summary (Cont d) Accelerated junctional rhythm same morphology as junctional escape rhythm heart rate is 60 to 100 beats per minute Junctional tachycardia rhythm same morphology as junctional escape rhythm heart rate exceeds 100 beats per minute Chapter Summary (Cont d) Supraventricular tachycardia rhythm may originate above the ventricles presents with a normal-narrow-appearing QRS complex heart rate greater than 150 beats per minute 6