Ecg analysis, july 2011

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Ecg analysis, july 2011

  1. 1. McGill/CDH Redevelopment Team Cardiac Electrophysiology Rhythm InterpretationCardiac Electrophysiology – Rhythm Interpretation Page 1
  2. 2. McGill/CDH Redevelopment TeamPrepared by Kathleen Brownrigg, BSc, RN, MSNNurse Educator, MUHCJuly 2011Chapter One: Electrophysiology and the Cardiac Monitor1.0 Cardiac Monitor and significance1.1 Electrical Activity of the Heart1.2 Linking Conduction to the Cardiac Cycle1.3 ECG Paper1.4 Waveform Analysis 1.4.1 The P Wave 1.4.2 PR Interval 1.4.3 QRS Complex 1.4.4 ST Segment 1.4.5 T Wave 1.4.6 Summary of ECG Interval1.5 Monitoring Leads1.6 Trouble ShootingChapter Two: Basic Rhythm Interpretation2.0 The Ten Step Method of Rhythm Interpretation2.1 Documentation and Thought Provoking ItemsChapter Three: Rhythms3.0 Normal Sinus3.1 Sinus DysrhythmiaCardiac Electrophysiology – Rhythm Interpretation Page 2
  3. 3. McGill/CDH Redevelopment Team3.2 Sinus Bradycardia3.3 Sinus Tachycardia3.4 Premature Atrial Contractions3.5 Supraventricular Tachycardia3.6 Atrial Flutter3.7 Atrial Fibrillation3.8 Junctional Rhythms3.91 Junctional Escape Rhythm3.92 Premature Junctional Contraction3.93 Junctional Tachycardia4.0 Atrioventricular Blocks 4.1.1 First Degree 4.1.2 Second Degree 4.1.3 Third Degree5.0 Premature Ventricular Contractions5.1 Ventricular Tachycardia5.2 Ventricular Fibrillation5.3 Idioventricular5.4 Asystole5.5 Pulseless Electrical Activity (PEA)5.6 Electrolyte ImbalancesReference ListEditorial NoteThis module was designed to address the learning needs of the nurse who has no priorknowledge of cardiac rhythms and rhythm disturbances. The module does not use theclassification outlined in the ACLS standards. In addressing treatment options andmanagement of dysrhythmias, ACLS protocols should be followed.Learning ObjectivesCardiac Electrophysiology – Rhythm Interpretation Page 3
  4. 4. McGill/CDH Redevelopment TeamUpon completion of this learning package and participation in classroom instruction thelearner will be able to:  Identify each part of the ECG waveform and normal measurement  Employ the 10-step method of ECG interpretation  Identify basic arrhythmias, their etiology and relate clinical significanceCardiac Electrophysiology – Rhythm Interpretation Page 4
  5. 5. McGill/CDH Redevelopment Team Chapter One: Electrophysiology and the Cardiac Monitor1.0 Cardiac Monitor and Significance • Continuous electronic monitoring is an adjunct to patient care and assessment • Monitors are not substitutes for appropriate nursing or physician assessment • Monitors and their alarms provide an alert when the patient’s vital signs deviate outside an identified acceptable range • Monitors provide us with the ability to continuously observe the electrical activity occurring within the cardiac muscle • The current generated by the electrical cells radiate from the heart, through the surface of the skin and into the electrodes placed on the chestCardiac Electrophysiology – Rhythm Interpretation Page 5
  6. 6. McGill/CDH Redevelopment Team • The monitor is able to transform the electrical activity into the waveforms that represent the cardiac cycle • It does not replace actual physical assessment, our “hands on” assessment should correlate with the ECG tracing • It is not enough to say the heart tracing is fast, slow or unusual looking but how the patient is tolerating it (pulse, capillary refill, skin color, temp, BP etc)Cardiac Electrophysiology – Rhythm Interpretation Page 6
  7. 7. McGill/CDH Redevelopment Team1.1 The Conduction System of the Heart The heart’s primary pacemaker is the sino-atrial node located in the rightatrium near the inflow tract of the superior and inferior vena cava. It has an inherentrate of 60-100 beats per minute. The conduction pathways carry the impulse via theinternodal tracts through the atrial tissue and down to the atrio-ventricular node. TheAV node is located near the intraventricular septum near the tricuspid valve. Impulsesare delayed in the AV node for a few milliseconds to allow the ventricles to filladequately before systole. Connected to the AV node in the Bundle of His which is made up of thickconducting nerve fibres. This bundle divides into the right and left bundle branches andcarriers current through the ventricles via the Purkinje Fibres. These fibres areembedded in the myocardium causing depolarization and repolarization. If the SA node fails, the heart has a protective back up system of pacemakerswhich continue to stimulate the myocardium. The AV node or secondary pacemakerhas an intrinsic rate of 40-50 beats per minute. If the SA node and the AV node both fail then the tertiary pacemaker is found inthe Prukinje Fibres. This process is called inherent rhythmicity. The rate is 20-40breaths per minute and provides minimal perfusion of vital organs. It usually causesserious symptoms.Cardiac Electrophysiology – Rhythm Interpretation Page 7
  8. 8. McGill/CDH Redevelopment TeamCardiac Electrophysiology – Rhythm Interpretation Page 8
  9. 9. McGill/CDH Redevelopment Team 1.1 Electrical Activity of the Heart • Intracellular and extracellular fluids contain positive and negative ions • These ions enable each cell to initiate and respond to electrical impulses • The ions flow across the cellular wall membrane creating a wave of electrical conduction + + ++ • The primary ions of importance are Na , K and Ca  The resting state, known as polarization, there is no electrical activity + + ++ taking place within the cell → K is within the cell and Na and Ca are outside the cell  The discharge state, known as depolarization, the cell is electrically stimulated causing the ions to pass across the cellular membrane →The + + ++ k moves out of the cell and the Na and Ca move in  The recovery state, known as repolarization, the cell is returning to the resting state and is unable to respond to any further electrical + + stimulation→ The k once again moves back into the cell and the Na and ++ Ca moves back out (original state) • All three electrical events (polarization , depolarization and repolarization ) will lead to visual waveforms on the cardiac monitor and ultimately is responsible for the mechanical contraction of the heartCardiac Electrophysiology – Rhythm Interpretation Page 9
  10. 10. McGill/CDH Redevelopment Team +  The cardiac muscle and purkinji cells are very sensitive to K ++ and Ca influxes, therefore electrolyte disturbances can and will grossly affect the ECG waveforms and the ultimate cardiac function1.2 Linking conduction to the Cardiac CycleCardiac Electrophysiology – Rhythm Interpretation Page 10
  11. 11. McGill/CDH Redevelopment Team1.2 The Principals of Monitoring The ECG monitor reflects the electrical activity of cardiac cells. On specialized grid/graph paper, electrical activity of the heart is recorded on two planes at either 25 mm/sec, which is the standard, or at 50 mm/sec, an alternative method often used when drug studies are being conducted.The Horizontal Axis represents the length of each particular electrical event with itsduration in time. • One small block represents 0.04 seconds • Five small blocks form the base of a large block, which is shown by heavier lines and represents 0.20 seconds • One may measure the duration of a waveform or segment by counting the number of blocks and comparing with a normal rangeCardiac Electrophysiology – Rhythm Interpretation Page 11
  12. 12. McGill/CDH Redevelopment Team • Ticks on the top of the paper represent 3-second intervals (15 boxes) this helps when calculating heart ratesThe Vertical Axis represents the electrical voltage in millivolts (mV) oramplitude (mm) of each particular event. • The amplitude/height of the wave segment or intervals is calculated by measuring the number of blocks from the isoelectric line to the highest point of the wave segment or interval.ECG PaperCardiac Electrophysiology – Rhythm Interpretation Page 12
  13. 13. McGill/CDH Redevelopment Team1.4 Waveform analysis • On the cardiac monitor one normal cardiac cycle includes: I. The P wave II. The QRS complex (consisting of a Q, R, and S wave) III. The T wave • These units of electrical activity are further broken down into the following intervals or segments: I. The PR interval II. The ST segment • The isoelectric line is the baseline of the cycle with no positive or negative deflections (the polarized state)Cardiac Electrophysiology – Rhythm Interpretation Page 13
  14. 14. McGill/CDH Redevelopment Team1.4.1 The P Wave:  Reflects atrial depolarization  First upright deflection  Should be a rounded shape without a notch or peak  Indicates the SA node initiated an impulseCardiac Electrophysiology – Rhythm Interpretation Page 14
  15. 15. McGill/CDH Redevelopment Team1.4.2 PR Interval  Represents AV node delay or conduction  The time it takes for the atria to contract and expel the remaining (10-25%) blood into the ventricles, known as the “atrial kick”  Normal PR interval in an infant is 0.08 - 0.13 seconds (2-3 small boxes) and toddler 0.10- 0.14 seconds (2.5 - 4 small boxes) and adult is 0.12- 0.20 seconds (3-5 small boxes)  For simplicity a PR interval is within normal measures if it is between 2-4 small boxes in newborns and small children1.4.3 QRS Complex  Represents ventricular depolarization  Atrial repolarization occurs but its wave is buried in the QRS complex  Begins from the first deflection (either +ve or –ve) that follows the P wave  Normal QRS duration is 0.04- 0.08 sec in infants and small children extending to 0.12 seconds in adultsCardiac Electrophysiology – Rhythm Interpretation Page 15
  16. 16. McGill/CDH Redevelopment Team  For simplicity a QRS is within normal measures if less than three small boxes1.4.4 ST Segment  Connects the QRS complex to the T wave  Under normal circumstances should be at the isoelectric line  Represents the time it takes for the ventricles to contract and expel blood into the major arteries1.4.5 T wave  Represents ventricular repolarization  Should be rounded  Changes in T wave may indicate electrolyte imbalance or myocardial infarctionCardiac Electrophysiology – Rhythm Interpretation Page 16
  17. 17. McGill/CDH Redevelopment Team1.4.6 Summary of ECG interval (note adult norms for time)1.5 MonitoringleadsCardiac monitoring providesa continuous assessment of apatient’s heart rate and rhythm.Cardiac Electrophysiology – Rhythm Interpretation Page 17
  18. 18. McGill/CDH Redevelopment TeamMost bedside cardiac monitors provide a three-lead system which allow one view of theheart to be seen. There is also a 5-lead system which allows two simultaneous views ofthe heart’s activity. • The leads are often red (+ve), white (-ve) and black (ground) • To recall lead placement for the 3 lead system remember “White on the right” and “smoke above the fire” (black lead over the red lead on the left) • Lead II is preferred for observing the patients underlying rhythm, as this lead produces the most upright waveforms and is best for dysrhythmia detectionWith the three lead system, either lead II or the Marriott (MCL) lead is used.Advantages of Lead II:1 – Allows for clear visualization of the atrial activity–2 - Allows for upright R waves which is needed for procedures such as cardioversionCardiac Electrophysiology – Rhythm Interpretation Page 18
  19. 19. McGill/CDH Redevelopment TeamAdvantages of MCL1 – Useful to differentiate L vs. R ventricular ectopic2 – Useful in identifying L vs. R bundle branch blocks.Advantages of 5 Lead System:Allows viewing of seven possible modifiedLeads including lead I, II, III, AVR, AVL, AVF,and V.The difference between continuous electronic monitoring and 12 Lead ECG is that theformer is used for monitoring only, why the latter provides an additional diagnostic toolfor the cardiac patient, either for confirmation or ruling out of a cardiac problem,especially myocardial infarction.A 12-Lead ECG provides 12 different views of the heart instead of one or two.1.6 Trouble ShootingArtifact • Lines or waveforms produced on the ECG tracing that are not reflective of the hearts electrical activity60-cycle interferenceCardiac Electrophysiology – Rhythm Interpretation Page 19
  20. 20. McGill/CDH Redevelopment Team • a thick fuzzy baseline is displayed on the ECG tracing, often caused by electrical interferenceWandering baseline • the tracing intermittently rises and fallsmost common causes  Patient movement  Hiccups, shivering, seizures and chest movement related to respirations  Improper electrode placement  Electrode gel has not dried out  Inadequate contact between electrode and skin  Skin excoriation under electrode patch  Broken monitor lead wires or cracks  Room outlets for damaged plugs  Electrical interference from other sources (other equipment)Straight baseline • No ECG tracing is produced!! your patient for presence of pulse and respirations (your ABCDs)then,  for all the common causes of artifact above REMEMBER TO TREAT YOUR PATIENT NOT YOURCardiac Electrophysiology – Rhythm Interpretation Page 20
  21. 21. McGill/CDH Redevelopment Team MONITORCardiac Electrophysiology – Rhythm Interpretation Page 21
  22. 22. McGill/CDH Redevelopment Team Chapter Two: Basic Rhythm Interpretation • Electrocardiography is the process of creating a visual tracing of the electrical activity of the cells in the heart, for the purpose of identifying and analyzing dysrhythmias. • One must use a systematic approach that enables you to assess the rhythm that you are viewing. • Using a consistent method will help to enhance your assessment, confidence and comfort level. • The Chest Disease Hospital will use a 10-Step Method to Rhythm Analysis which is a clear step by step approach.2.0 The Ten Step Method 1. Assess your A, B, C, and Ds!Cardiac Electrophysiology – Rhythm Interpretation Page 22
  23. 23. McGill/CDH Redevelopment Team 2. Assess the ventricular heart rate 3. Evaluate the regularity of the rhythm 4. Assess the P wave 5. Evaluate the PR interval 6. Assess the P:QRS 7. Evaluate the QRS complex 8. Assess the ST segment 9. Identify the rhythm 10. Determine the clinical significance**Always analyze a 6 second rhythm strip.1. Assess your patient (C, A, B, Ds) • Circulation, Airway, Breathing, Disability (or Neurological functioning) • If your ABC and D’s are not stable, don’t worry about the rhythm interpretation. Treat your patient first!!!2. Assess the Heart Rate (HR) • The simplest method for assessing heart rate is the 10 times method • Obtain a 6 second rhythm strip (30 boxes) • Count the number of QRS in a 6 second strip and multiply by 10 for the ventricular rate • Count the number of P waves in a 6 second strip and multiply by 10 for the atrial rate • This method works for both regular and irregular rhythmsCardiac Electrophysiology – Rhythm Interpretation Page 23
  24. 24. McGill/CDH Redevelopment Team • Compare the HR with the normal values as well as the patient’s baseline.3. Evaluate the Regularity of the Rhythm • Take a second piece of paper and mark the top of consecutive P waves in the strip; one can then compare the distance between each P-P interval on the strip • This same method can be done to compare the highest point of the QRS complex and then compare all the R-R intervals • If these distances are constant and the measured waves are at regular intervals then the rhythm is said to be regular • If the interval varies then the rhythm is considered irregular • If irregular, then note how irregular the rhythm is. Does the irregularity occur in a pattern? Is it only one irregular (premature/delayed) beat.4. Assess the P wave • Is it present? • It should be before the QRS complex • Does every P have a QRS following? • It should be upright, rounded and look the same throughout (size and shape)5. Assess the PR Interval • Locate the PR Interval from the beginning of the P Wave to the beginning of the QRS complex • Count the number of small boxes and multiply this number by 0.04 to obtain actual seconds • The normal PR interval in an adult is 0.12- 0.20 seconds (3-5 small boxes)Cardiac Electrophysiology – Rhythm Interpretation Page 24
  25. 25. McGill/CDH Redevelopment Team6. Assess the P:QRS relationship • This atrial to ventricular association should be 1:1 • Is there a P wave preceding every QRS? • Is there only one P wave per QRS? • Is there only one QRS for every P wave?7. Evaluate the QRS complex • The most critical assessment parameter (represents ventricular activity) • Are all QRS complexes the same size and shape? • What is the duration of the complex? • Count the number of boxes from the beginning of the Q wave to the end of the S wave where it meets the isoelectric line • Normal QRS is less than 3 small boxes (0.12 sec.) in an older child/adult • For simplicity a QRS complex should be ‹ 3 small boxes8. Assess the ST segment/T wave • Please refer to section 4.4.4 and 4.4.5 • Observe the S wave as it returns to the isoelectric line • Is it elevated or depressed as it rises towards the baseline? • Do the T waves look the same throughout (uniform)? • T waves should be ¼ to ½ the QRS height • Are the T waves positive (upward), inverted, peaked, rounded or flat?9. Identify the Rhythm • What is the underlying rhythm?Cardiac Electrophysiology – Rhythm Interpretation Page 25
  26. 26. McGill/CDH Redevelopment Team • Is it fast? Is it slow? Is it regular? Is it irregular, is it sinus? • Are there extra beats? Premature ones? Couplets and so on? • Are they atrial or ventricular in nature?10. Determine the Clinical Significance • Correlate your patient assessment with your ECG interpretation • How is your patient tolerating the rhythm? • Anticipate the interventions that may be necessary2.1 Documentation and Thought Provoking Items • Documentation is a necessary part of nursing care • One must document their assessment, plan, implementation and evaluation within the charting record • When a patient is on a cardiac monitor, alarm parameters must be verified at shift change with the routine safety check and signed as such on the flow sheet • HR alarm limits should be set at a maximum of 50% above and 35% below the patient’s baselineCardiac Electrophysiology – Rhythm Interpretation Page 26
  27. 27. McGill/CDH Redevelopment Team • The nursing notes should include when the patient was put on a cardiac monitor and why it was indicated • Nursing notes should also include when and why the monitor was discontinued • Six second recording strips should be printed and included in the patient chart once per shift and in the event of a changing rhythm (dated and timed) • Anytime an arrhythmia is noted, document your assessment of any clinical significance to the patient and any action taken • Remember, assess and treat your patient not the monitor…… AND assess your patient well!! Chapter Six: RhythmsAbbreviations used for 10 step method:Cardiac Electrophysiology – Rhythm Interpretation Page 27
  28. 28. McGill/CDH Redevelopment TeamCRT- capillary refill timeWNL- within normal limitsTx- treatmentbpm- beats per minute3.0 Normal Sinus10 steps…1.2.3.4.5.6.7.8.Cardiac Electrophysiology – Rhythm Interpretation Page 28
  29. 29. McGill/CDH Redevelopment Team9.10.3.1 Sinus Dysrhythmia • Also known as a respiratory arrhythmia • Inspiration decreases vagal tone and HR↑, expiration increases the vagal tone and therefore ↓ HR • Extreme variances may be due to airway obstruction or increased ICP10 steps…1. Warm, pink, CRT≤ 2 seconds, happy, voiding and VS WNL for age2.3.4.Cardiac Electrophysiology – Rhythm Interpretation Page 29
  30. 30. McGill/CDH Redevelopment Team5.6.7.8.9.10.Tx-3.2 Sinus Bradycardia • Slower than normal for age • May be normal depending on etiology and length of time sustained • Negative consequences if sustained for long periods, with a decrease in cardiac output (CO)Etiology:  During sleep  Vagal stimulation (suctioning, vomiting, bearing down etc.)  Hypoxia  Anaesthetic agents  Electrolyte imbalances  Acid-base imbalances  Hypoglycaemia  Hypothermia  Increased ICP  Drug toxicityCardiac Electrophysiology – Rhythm Interpretation Page 30
  31. 31. McGill/CDH Redevelopment TeamSinus Bradycardia10 steps… 1. symptoms range from none to S&S of decreased CO 2. 3. 4. 5. 6. 7. 8. 9. 10.Tx-Cardiac Electrophysiology – Rhythm Interpretation Page 31
  32. 32. McGill/CDH Redevelopment Team3.3 Sinus Tachycardia • Faster HR than expectedEtiology:  Sympathetic stimulation e.g. anxiety, pain, medication  Infection  Fever  Hypovolemia  Anaemia  Respiratory distress  ↑ activity  Hyperthyroidism  Myocarditis/ pericarditis  HydropsSinus Tachycardia10 steps… 1. Generally well tolerated but may produce S&S associated with ↓CO 2. 3. 4.Cardiac Electrophysiology – Rhythm Interpretation Page 32
  33. 33. McGill/CDH Redevelopment Team 5. 6. 7. 8. 9. 10.Tx –3.4 Premature Atrial Contraction(PAC) • An early beat that originates in a pacemaker cell of the atria, other than the SA node • Also known as APBs (atrial premature beats)Etiology:  SNS stimulation (including caffeine)  Hypoxia  Anxiety/pain  Electrolyte imbalances  Sepsis  Structural heart disease and following open heart (atrial) surgery  Hyperthyroidism  Digitalis toxicityCardiac Electrophysiology – Rhythm Interpretation Page 33
  34. 34. McGill/CDH Redevelopment TeamPAC10 steps…. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.Tx-3.5 Supraventricular Tachycardia (SVT) • rapid sustained rhythm with a rate 150 – 250 bpm • no change in rate despite activity (fixed rate with no variability)Cardiac Electrophysiology – Rhythm Interpretation Page 34
  35. 35. McGill/CDH Redevelopment Team • if there is only time for one waveform the larger one will be seen; the P wave is often hidden or stacked within the T waveEtiology:  70% are idiopathic (cause unknown)  Cardiac defects and/or post cardiothoracic surgery  Conduction defects such as Wolff-Parkinson-White syndrome  Myocarditis  Systemic infections10 steps… 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.Cardiac Electrophysiology – Rhythm Interpretation Page 35
  36. 36. McGill/CDH Redevelopment TeamTx3.6 Atrial Flutter • Increased automaticity of atrial cells or a re-entry mechanism produces a rapid atrial rate > 250 beats per minute • P waves are saw-toothed in shape • S&S of ↓ CO may develop due to loss of atrial kick • Ventricular rate may be normal, however irregular in rhythmEtiology  Usually seen post-op cardiothoracic surgery  Structural heart disease with dilated atria10 steps…Cardiac Electrophysiology – Rhythm Interpretation Page 36
  37. 37. McGill/CDH Redevelopment Team 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.Tx3.7 Atrial Fibrillation • Disorganized state of electrical activity within the atrium • Chaotic baseline producing 400-700 depolarizations a minute • Ventricular rate WNL, irregular pulse • ↓ CO due to loss of atrial kickEtiology  InfectionCardiac Electrophysiology – Rhythm Interpretation Page 37
  38. 38. McGill/CDH Redevelopment Team  Hypoxia  CHD with dilated atria  Pericarditis  Digoxin toxicity  Electrolyte imbalance  Post-op atrial surgery10 steps… 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.TxCardiac Electrophysiology – Rhythm Interpretation Page 38
  39. 39. McGill/CDH Redevelopment Team3.8 Junctional Rhythms • Rhythms that originate from the AV node. • They replace the activity of the SA node when the latter fails, therefore, the heart’s secondary pacemaker. • P waves may be inverted because the atria are depolarized in a retrograde conduction. P waves can be closer, lost in or follow the QRS complex. PR Intervals are < 0.12 seconds in the P wave precedes the QRS complex. • Junctional arrhythmias can occur in the presence of organic heart disease, atrial ischemia, myocardial infarction, or excessive digitalis.3.91 Juntional Escape Rhythm • Ventricular rate 40-60 bpm • QRS duration < 0.12 sec • May lead to heart failure and decreased cardiac output10 StepsCardiac Electrophysiology – Rhythm Interpretation Page 39
  40. 40. McGill/CDH Redevelopment Team1.2.3.4.5.6.7.8.9.10.Tx-Cardiac Electrophysiology – Rhythm Interpretation Page 40
  41. 41. McGill/CDH Redevelopment Team3.9.2 Premature Junctional Contraction • Can be caused by excessive digitalization, Quinidine, or organic heart disease. • PR Interval < 0.12 sec • Also called premature nodal contraction10 Steps1.2.3.4.5.6.7.8.9.10.Tx-3.9.3 Junctional Tachycardia • Rate 100-180 bpm • Occurs when the AV junction becomes irritable, speeds up and overrides higher pacemaker sites • Rhythm is regularCardiac Electrophysiology – Rhythm Interpretation Page 41
  42. 42. McGill/CDH Redevelopment TeamCardiac Electrophysiology – Rhythm Interpretation Page 42
  43. 43. McGill/CDH Redevelopment Team4.0 Atrioventricular Blocks • Problems associated with the conduction of an impulse through the AV node or bundle branches • Classified upon the severity of conduction disturbanceTypes  First Degree Heart Block  Second Degree Heart block Type I second degree = Mobitz I= Wenckebach Type II second degree = Mobitz II  Third Degree Heart Block= Complete Heart Block= AV dissociation4.1.1 First Degree Heart Block • PR interval is prolonged, due to the atypical delay of conduction as the sinus impulse travels through the AV node • PR interval is prolonged but constantEtiology  Effects of digitalis, propanolol and quinidine  Hyperkalemia  Hypoxemia  CHD  Following heart biopsy, cardiac catheterization or surgery  Myocarditis, endocarditis or tumors  Rheumatic fever, scarlet fever, mumps or rubella  ↑vagal tone (e.g. ↑ ICP, ↑ BP or gastric distension)Cardiac Electrophysiology – Rhythm Interpretation Page 43
  44. 44. McGill/CDH Redevelopment Team10 steps… 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.Tx4.1.2 Second Degree Heart BlockType I second degree = Mobitz I = Wenckebach • More common than Type IICardiac Electrophysiology – Rhythm Interpretation Page 44
  45. 45. McGill/CDH Redevelopment Team • Impulses travelling from the atria are delayed progressively, lengthening the PRI until one is not conducted at all and results in the QRS complex being dropped • Resultant rhythm irregular • Usually transient and prognosis is quite goodEtiology  Digitalis or propanolol toxicity  ↑ Vagal tone  Hypoxemia  CHD  Degenerative cardiomyopathy  Myocarditis  Post cardiac surgery  Acute rheumatic fever  During sleep in healthy childrenMobitz I10 steps….. 1. 2. 3. 4. 5. 6. 7. 8. 9.Cardiac Electrophysiology – Rhythm Interpretation Page 45
  46. 46. McGill/CDH Redevelopment Team 10.Tx-Type II second degree= Mobitz II • More advanced and severe than Type I • May progress to Third Degree Heart Block • AV conduction is “all or none”, there is either normal AV conduction with a normal PR interval or the conduction is completely blocked • The impulses are blocked intermittently or at a fixed ratio (2:1, 3:1 etc) • The PR interval is what differentiates Type I from Type II; in Type I there is a clear warning as the PR interval lengthens, however, in Type II the PR interval remains constant with the QRS being dropped without warningEtiology  Cardiac drugs  Hypoxemia  ↑ vagal tone  Post cardiac surgery  Degenerative cardiomyopathy  CHD  Myocarditis*more often more serious causes such as ischemia*Cardiac Electrophysiology – Rhythm Interpretation Page 46
  47. 47. McGill/CDH Redevelopment TeamMobitz II10 steps… 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.Tx –4.1.3 Third Degree Heart Block • Known as complete heart block or divorce (most severe block)Cardiac Electrophysiology – Rhythm Interpretation Page 47
  48. 48. McGill/CDH Redevelopment Team • No communication between the atria and the ventricles • May be congenital requiring a pacemaker within first few days of life • The ventricles or AV node generate their own impulses to compensate and improve COEtiology  Congenital ( 2° to intrauterine infection, maternal Lupus or connective tissue disorders)  Following cardiac surgery (initially due to swelling or later due to stunted tissue growth related to scar)  Poorly controlled diabetes  Collagen disorders  Cardiomyopathy, Myocarditis  Metabolic disorders  Tumors, structural diseases  Digitalis toxicityThird Degree Block10 steps…Cardiac Electrophysiology – Rhythm Interpretation Page 48
  49. 49. McGill/CDH Redevelopment Team 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.Tx-5.0 Premature Ventricular Contractions • Ventricle is a little irritable • The increased automaticity of the ventricular cell generates an electrical impulse, sooner than the expected sinus impulse • Produces an earlier wide QRS complex • This earlier beat has less stroke volume and often feels like a skipped beat • May have one irritable focus (unifocal) or more than one (multifocal) which is more serious • May occur with increased frequency or regularity causing a patternEtiology  Healthy children  CHD  HypoxiaCardiac Electrophysiology – Rhythm Interpretation Page 49
  50. 50. McGill/CDH Redevelopment Team  Electrolyte or acid-base imbalance (hypokalemia, hypocalcemia, hypomagnesemia, acidosis)  Post open heart surgery, inflammation of the heart, cardiac trauma  Medications (those that stimulate the Sympathetic Nervous System e.g. caffeine, epinephrine, aminophylline, dopamine etc.)  Invasive lines (central lines, PICC lines, UVCs etc.)  Sympathetic response, stress10 steps…. 1. 2.Cardiac Electrophysiology – Rhythm Interpretation Page 50
  51. 51. McGill/CDH Redevelopment Team 3. 4. 5. 6. 7. 8. 9. 10.Tx-5.10 Ventricular Tachycardia • PVCs are often the precursors to VT • Increased irritability of the ventricle causing the ventricles to fire at a rate close to 200 • The longer, more sustained and faster the rhythm, the more dangerousEtiology  electrocution  medications, digitalis toxicity  CHD, post open heart surgery, myocarditis  Hypoxia  Acidosis  Electrolyte imbalancesCardiac Electrophysiology – Rhythm Interpretation Page 51
  52. 52. McGill/CDH Redevelopment Team10 steps… 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.Tx-5.2 Ventricular Fibrillation • Chaotic, irregular depolarization of the ventricles producing no CO • No discernable P waves or regular QRS complexes seen, only wavy baseline • Lethal yet quickly reversed if defibrillator availableCardiac Electrophysiology – Rhythm Interpretation Page 52
  53. 53. McGill/CDH Redevelopment TeamEtiology  Post cardiac surgery  VT may lead to VF if not terminated  Electrolyte imbalances  Hypoxia  Acidosis  Drug ingestions  Electrocution10 steps…1.2.3.4.5.6.7.8.9.10.Tx-Cardiac Electrophysiology – Rhythm Interpretation Page 53
  54. 54. McGill/CDH Redevelopment Team5.3 Idioventricular • The dying heart • Ventricular escape mechanism (Purkinje Fibres) takes over pacing in the absence of a higher focus (the SA node and AV junction)Etiology  Rheumatic fever  Myocarditis  Severe hypoxia  Prolonged vagal stimulation  Digitalis toxicity  Overdose/ ingestion  Hypothermia  IdiopathicCardiac Electrophysiology – Rhythm Interpretation Page 54
  55. 55. McGill/CDH Redevelopment Team10 steps…1.2.3.4.5.6.7.8.9.10.Tx-5.4 Asystole • Also known as ventricular standstill • All electrical activity ceases, no exchange of ions • Cannot defibrillate asystole • Patients rarely go directly from NSR to asystole, there is usually a gradual slowing before stopping e.g. the idiopathic rhythm • Treatment prognosis is poor; the goal is to prevent the conditions that cause asystoleCardiac Electrophysiology – Rhythm Interpretation Page 55
  56. 56. McGill/CDH Redevelopment TeamEtiology  Hypoxia  Hyperkalemia  Hypokalemia  Hypothermia  Acidosis  Drug overdose10 steps… 1. Assess your ABCDs  Confirm asystole in more than one lead (what appears like asystole in one lead could be fine VF that may have a chance of converting with defibrillation)  Rule out a technical problem 2. Once asystole confirmed….Forget the 10 steps and start CPR with epinephrine!!Cardiac Electrophysiology – Rhythm Interpretation Page 56
  57. 57. McGill/CDH Redevelopment Team5.5 Pulseless Electrical Activity (PEA) • Organized electrical activity is on the ECG with absent pulses • Includes electromechanical dissociation (EMD) • Treated the same as asystoleEtiology  Severe hypoxemia  Severe acidosis  Severe hypovolemia  Tension pneumothorax  Cardiac tamponade  Profound hypothermia  Drug ingestionsTx-5.6 Electrolyte Imbalances  Electrolyte imbalances most frequently associated with ECG changes include abnormal potassium, calcium and magnesium levels. +Hyperkalemia (serum K ↑)Cardiac Electrophysiology – Rhythm Interpretation Page 57
  58. 58. McGill/CDH Redevelopment Teampeaked T wave • Most common ECG change is tall and peaked T waves (monitor may double count HR due to large T waves) • Additional findings may include: -elevated ST segments -widened or flattened P waves -widened QRS complexes -more frequent PVCs and other ventricular arrhythmiaselevated ST segments +Hypokalemia (serum K ↓) • T wave is generally flat or inverted • Presence of another wave after the T wave, known as a U wave • PR interval may be prolonged • QRS may be wideCardiac Electrophysiology – Rhythm Interpretation Page 58
  59. 59. McGill/CDH Redevelopment Team +2Hypercalcemia (serum Ca ↑) • QT interval shorter than normal • Prolonged PR Interval • Severe cases, AV blocks may occur +2Hypocalcemia (serum Ca ↓)Cardiac Electrophysiology – Rhythm Interpretation Page 59
  60. 60. McGill/CDH Redevelopment Team • Prolonged QT interval • T waves may become flatter Various wave patterns indicative of electrolyte imbalances, acid/base disturbances, hypoxia, ischemia, drug ingestions etc.Cardiac Electrophysiology – Rhythm Interpretation Page 60
  61. 61. McGill/CDH Redevelopment Team Remember to assess and treat your patient not the monitor …..AND assess your patient well !!!Cardiac Electrophysiology – Rhythm Interpretation Page 61
  62. 62. McGill/CDH Redevelopment Team Reference List ndAehlert, B. (2002). ECGs Made Easy (2 ed.). Toronto: Mosby.Cardiac Electrophysiology – Rhythm Interpretation Page 62
  63. 63. McGill/CDH Redevelopment TeamBloedel-Smith, J., Ley, S.J., Curley, M.A., Elixon, E.M., & Dodds, K.M. (1996). TissuePerfusion. In M.A. Curley, J. Bloedel-Smith & P.A. Moloney-Harmon, Critical CareNursing of Infants and Children (pp. 155-178). Toronto: W.B. Saunders Company.Chameides, L., & Hazinski, M.F. (Eds.). (1997). Pediatric Advanced Life Support.American Heart Association.Chernecky, C. (2002). Real World Nursing Survival Guide: ECGs & the Heart. Toronto:W.B. Saunders Company.Curley, M.A. (1995). Pediatric Dysrhythmias. London: Prentice Hall.Dibert, C., & Marville-Williams, C. (2002). Basic Rhythm Interpretation and Intervention.Mississauga: Trillium Health Centre.van Doornik, N., Edmond, L., & Bruce, E. (2002). Basic Pediatric ECG Interpretation-Level 1. Toronto: Hospital for Sick Children.Hazinski, M.H. (1999). Nursing Care of the Critically Ill Child . St. Louis: Mosby.Pilcher, J. (1998). Pocket Guide to Neonatal EKG Interpretation. California: NICU InkBook Publishers.Sansoucie, D.A., & Cavaliers, T.A. (1997), Transition from Fetal to ExtrauterineCirculation. Neonatal Network, 16(2), 5-11.Slota, M.C.(1998). Core Curriculum for Pediatric Critical Care Nursing . Pennsylvania:W.B. Saunders Company.Cardiac Electrophysiology – Rhythm Interpretation Page 63
  64. 64. McGill/CDH Redevelopment TeamTappero, E.P., & Honeyfield, M.E. (1996). Physical Assessment of the Newborn: A ndComprehensive Approach to the Art of Physical Assessment: (2 ed.). California: NICUInk Book Publishers.Cardiac Electrophysiology – Rhythm Interpretation Page 64

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