1. 1 Lecture Notes Chapter 18 Electrocardiogram and Cardiac Arrhythmias Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

2. 2 Helpful Hints  Depolarize = Depolarize = Contracts  Systolic  Afterload  Repolarize = Repolarize = Recover  Diastolic  Preload

3. 3 Normal Electrocardiogram (ECG) EKG  Electrocardiograph  Detects micro-voltage changes as the heart depolarizes and repolarizes  How? - Leads  ECG “leads” (electrode configurations) Plots electrical activity that creates depolarization and repolarization Plots electrical activity that creates depolarization and repolarization Leads are placed on chest, arms, and legs Leads are placed on chest, arms, and legs Bipolar standard limb leads Bipolar standard limb leads Unipolar limb and chest leads Unipolar limb and chest leads Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

4. 4 ECG Components  Waves and complexes  P wave = atrial depolarization  QRS complex = ventricular depolarization 0.08 to 0.10 sec 0.08 to 0.10 sec  T wave = ventricular repolarization  Wave height (amplitude) = voltage Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

5. 5 Fig. 18-2 Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc. ECG Components

6. 6 ConceptQuestion 18-1  A high amplitude P wave may be associated with what type of abnormality?

7. 7 ECG Components  Intervals and segments  PR interval From SA node to ventricles From SA node to ventricles 0.12 to 0.20 sec 0.12 to 0.20 sec  J point QRS _______________________________________ QRS _______________________________________  ST segment Flat, lying on baseline is normal Flat, lying on baseline is normal Depressed >0.5 mm = ________________________ Depressed >0.5 mm = ________________________ Elevated >2 mm = ________________________________ Elevated >2 mm = ________________________________ Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

8. 8

9. 9 ECG Components  Intervals and segments  QT interval ________________________________________ ________________________________________ Usually less than __________ seconds Usually less than __________ seconds The ventricle is in the refractory period The ventricle is in the refractory period  Refractory Period ____________________________________ Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

10. 10 ECG Graph Paper  Grid  1 mm (smallest square) vertical = 0.1 mV  1 mm horizontal = 0.04 sec  Heavy 5 mm lines (big square) = 0.20 sec & 0.5 mV  5 large squares = 25 mm (about 1 inch) = 1 sec  25 mm/sec graph speed Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

11. 11 ECG Graph Paper Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc. Fig. 18-5

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13. 13 ECG Leads Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc. Fig. 18-9

14. 14 Hexaxial Reference Figure Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc. Fig. 18-11

15. 15 Identifying Common Arrhythmias  Systematic ECG analysis  Steps  1: Identify waves and complexes  2: Analyze QRS complexes  3: Analyze P waves  4: Assess AV relationship Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

16. 16 Identifying Common Arrhythmias Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc. Box 18-2

17. 17 Normal Sinus Rhythm  Sinus node initiates each depolarization  Rate: 60 to 100 beats/min  P wave-QRS complex ratio is 1:1  Spacing between QRS is constant  PR interval is <0.16 sec Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

18. 18 Normal Sinus Rhythm Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc. Fig. 18-16 Heart Rate _______

19. 19 Abnormal Sinus Rhythms  Tachycardia  Sinus tachycardia HR >100 beats/min HR >100 beats/min Regular and rhythmic Regular and rhythmic Causes Causes  Exercise, fever, anxiety, pain, coffee, smoking, hypoxia  Beta adrenergic drugs Treatment: OXYGEN… Then, focus on underlying cause Treatment: OXYGEN… Then, focus on underlying cause Additional Treatment: Vagal Stimulation Additional Treatment: Vagal Stimulation =_____________________________________ =_____________________________________  A rapid heart rate __________________________ _________________________________________ _ Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

20. 20 Abnormal Sinus Rhythms Tachycardia Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc. Fig. 18-17 Heart Rate _______

21. 21 Abnormal Sinus Rhythms Bradycardia  Bradycardia  Sinus bradycardia HR <60 beats/min HR <60 beats/min Regular and rhythmic Regular and rhythmic Normal in sleep, physically conditioned individuals Normal in sleep, physically conditioned individuals Carotid sinus syndrome; overly sensitive pressure receptors (vagal) in the neck… If stimulated = syncope Carotid sinus syndrome; overly sensitive pressure receptors (vagal) in the neck… If stimulated = syncope SYNCOPE = _________________ SYNCOPE = _________________ Gagging can also cause bradycardia (Suctioning) Gagging can also cause bradycardia (Suctioning) Symptomatic bradycardia Symptomatic bradycardia  hypotension, weakness, sweating, syncope Treatment: atropine; pacemaker Treatment: atropine; pacemaker Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

22. 22 Abnormal Sinus Rhythms Bradycardia Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc. Fig. 18-18 Heart Rate _______

23. 23 Abnormal Sinus Rhythms  Sinus arrhythmia  Irregularly generated sinus node impulses  Alternate between fast and slow rates  Irregular spacing between QRS complexes  Follows inspiration & expiration (↑rate insp.; ↓exp.)  No clinical significance and do not require treatment Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

24. 24 Abnormal Sinus Rhythms Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc. Fig. 18-19

25. 25 Premature Atrial Contraction (PAC)  Ectopic focus fires = early atrial contraction  QRS complexes are ____________ but ___________ _____________  Stress, alcohol, tobacco, caffeine, electrolyte imbalances, sympathetic stimulation  Drugs: sodium & calcium channel inhibitors may be used: quinidine: verapamil Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

26. 26 Premature Atrial Contraction (PAC) Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc. Fig. 18-20

27. 27 Supraventricular Arrhythmias “Above the Ventricles”  Atrial flutter  Single ectopic pacemaker above AV node  Ectopic focus produces F waves (saw-toothed) “P waves are now F waves” “P waves are now F waves”  AV node normally blocks transmission of many F- waves  Atrial rate 200-350 bpm and regular; thus QRS rate is regular, but slower than atrial rate  Symptoms: palpitations, nervousness, anxiety, possible syncope if inadequate ventricular filling time  Treatment: Ca ++ blockers; electrical cardioversion Electrical Shock synchronized with heart rate Electrical Shock synchronized with heart rate Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

28. 28 Supraventricular Arrhythmias A-Flutter Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc. Fig. 18-21 Every 4 th atrial impulse is transmitted to ventricles, producing a regular QRS rhythm.

29. 29 Supraventricular Arrhythmias  Atrial fibrillation  Multiple randomly firing ectopic atrial foci  Atria “quiver” (no pumping) at 300-600 impulses/min; completely irregular  Loss of atrial kick = reduced ventricular filling→ reduced stroke volume & CO; occasional peripheral pulse deficit  Fine fibrillatory waves; slightly wavy baseline (no “Ps”)  Slower, irregular ventricular rate  Causes: conditions that ↑ atrial pressure & enlarge atria: longer depolarization route  May cause hypotension, fainting (syncope)  Pooling of blood in atria: thromboembolism risk: anticoagulant drugs important preventative treatment  Treatment: Ca ++ blockers; electrical cardioversion Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

30. 30 Supraventricular Arrhythmias A-Fib Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc. Fig. 18-22

31. 31 Junctional Arrhythmias  AV node assumes role of pacemaker  Junctional escape rhythm if SA node fails to fire  Inherent rate of 40 to 60 bpm  QRS normal shape and duration  Retrograde (backward) atrial conduction  Inverted, hidden, or retrograde P waves (after QRS)  Irritable junctional fibers cause PJC  Junctional tachycardias  Paroxysmal (PSVT): up to 240/min (caffeine, nicotine, alcohol, overexertion, electrolyte imbalance, etc.)  Nonparoxysmal (150/min): ↑junctional excitability (drug toxicity)  Treatment: vagal stimulation; IV adenosine; IV Ca ++ blocker Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

32. 32 ConceptQuestion 18-4  Why do chronic congestive heart failure and high atrial pressures predispose a person to the development of atrial fibrillation?

33. 33 Junctional Arrhythmias Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc. Fig. 18-24 Inverted P waves; slow heart rate

34. 34 Junctional Arrhythmias Junctional Tachycardia Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc. Fig. 18-25 No P waves

35. 35 Ventricular Arrhythmias  Premature ventricular contraction (PVC)  Ectopic focus/excitability arises from ventricles  QRS not preceded by P wave  Wide (>0.12 sec) and bizarre appearance  Generate T wave of opposite polarity (downward)  Followed by compensatory pause  Frequent PVCs signal life-threatening arrhythmia potential; highly irritable ventricular muscle fibers  Unifocal vs. multifocal PVCs  Bigeminy  Treatment: antiarrhythmic drug: lidocaine  OXYGEN! Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

36. 36 Ventricular Arrhythmias Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc. Fig. 18-26 Unifocal PVCs Multifocal PVCs: serious ventricular irritability

37. 37 Ventricular Arrhythmias  Ventricular tachycardia (V-Tach)  Successive “runs” of PVCs  Rate of 110-250/min  Treat as emergency: serious sign of ventricular irritability  QRS complexes bizarre and wide  High potential to progress to ventricular fibrillation  Treat with IV lidocaine or amiodarone  Cardioversion Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

38. 38 Ventricular Tachycardia Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc. Fig. 18-28

39. 39 Ventricular Arrhythmias  Ventricular fibrillation (VF)  Most lethal arrhythmia = cardiac arrest; CODE BLUE  Ventricles nonfunctional, quivering, no pumping ability  No recognizable waves or complexes  Requires electrical defibrillation—no drug can convert to normal rhythm  Equivalent to Cardiac Arrest. CPR must be initiated SHOCKABLE RHYTHM  Along with a shock, use: Epinephrine, Amiodarone, Lidocaine Epinephrine, Amiodarone, Lidocaine Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

40. 40 Ventricular Fibrillation Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc. Fig. 18-29

41. 41 ASYSTOLE