1 lecture notes chapter 18 electrocardiogram and cardiac arrhythmias copyright © 2007, 1998 by...

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Lecture NotesLecture NotesChapter 18Chapter 18

Electrocardiogram and Electrocardiogram and Cardiac ArrhythmiasCardiac Arrhythmias

Copyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

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Helpful HintsHelpful Hints

Depolarize = Depolarize = ContractsDepolarize = Depolarize = Contracts SystolicSystolic AfterloadAfterload

Repolarize = Repolarize = RecoverRepolarize = Repolarize = Recover DiastolicDiastolic PreloadPreload

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Normal Electrocardiogram (ECG)Normal Electrocardiogram (ECG)EKGEKG

ElectrocardiographElectrocardiograph Detects micro-voltage changes as the heart Detects micro-voltage changes as the heart

depolarizes and repolarizesdepolarizes and repolarizes

How? - LeadsHow? - Leads ECG “leads” (electrode configurations)ECG “leads” (electrode configurations)

• Plots electrical activity that creates depolarization and Plots electrical activity that creates depolarization and repolarizationrepolarization

• Leads are placed on chest, arms, and legsLeads are placed on chest, arms, and legs

• Bipolar standard limb leadsBipolar standard limb leads

• Unipolar limb and chest leadsUnipolar limb and chest leads


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ECG ComponentsECG Components

Waves and complexesWaves and complexes P wave = atrial depolarizationP wave = atrial depolarization QRS complex = ventricular depolarizationQRS complex = ventricular depolarization

• 0.08 to 0.10 sec0.08 to 0.10 sec

T wave = ventricular repolarizationT wave = ventricular repolarization Wave height (amplitude) = voltageWave height (amplitude) = voltage


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ConceptQuestion 18-1ConceptQuestion 18-1

A high amplitude P wave may be associated A high amplitude P wave may be associated with what type of abnormality?with what type of abnormality?

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Intervals and segmentsIntervals and segments PR intervalPR interval

• From SA node to ventriclesFrom SA node to ventricles

• 0.12 to 0.20 sec0.12 to 0.20 sec

J pointJ point• QRS _______________________________________QRS _______________________________________

ST segmentST 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 = ________________________________________________________________


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Intervals and segmentsIntervals and segments QT intervalQT interval

• ________________________________________________________________________________

• Usually less than __________ secondsUsually less than __________ seconds

• The ventricle is in the refractory periodThe ventricle is in the refractory period

Refractory PeriodRefractory Period

________________________________________________________________________


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ECG Graph PaperECG Graph Paper

GridGrid 1 mm (smallest square) vertical = 0.1 mV1 mm (smallest square) vertical = 0.1 mV 1 mm horizontal = 0.04 sec1 mm horizontal = 0.04 sec Heavy 5 mm lines (big square) = 0.20 sec & 0.5 Heavy 5 mm lines (big square) = 0.20 sec & 0.5

mVmV 5 large squares = 25 mm (about 1 inch) = 1 sec5 large squares = 25 mm (about 1 inch) = 1 sec

25 mm/sec graph speed25 mm/sec graph speed


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ECG Graph PaperECG Graph Paper

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

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ECG LeadsECG Leads


Fig. 18-9

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Hexaxial Reference FigureHexaxial Reference Figure


Fig. 18-11

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Identifying Common ArrhythmiasIdentifying Common Arrhythmias

Systematic ECG analysisSystematic ECG analysis StepsSteps

1: Identify waves and complexes1: Identify waves and complexes 2: Analyze QRS complexes2: Analyze QRS complexes 3: Analyze P waves3: Analyze P waves 4: Assess AV relationship4: Assess AV relationship


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Identifying Common ArrhythmiasIdentifying Common Arrhythmias


Box 18-2

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Normal Sinus RhythmNormal Sinus Rhythm

Sinus node initiates each depolarizationSinus node initiates each depolarization Rate: 60 to 100 beats/minRate: 60 to 100 beats/min P wave-QRS complex ratio is 1:1P wave-QRS complex ratio is 1:1 Spacing between QRS is constantSpacing between QRS is constant PR interval is <0.16 secPR interval is <0.16 sec


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Normal Sinus RhythmNormal Sinus Rhythm


Fig. 18-16

Heart Rate _______

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Abnormal Sinus RhythmsAbnormal Sinus Rhythms

TachycardiaTachycardia Sinus tachycardiaSinus tachycardia

• HR >100 beats/minHR >100 beats/min

• Regular and rhythmicRegular and rhythmic

• CausesCauses Exercise, fever, anxiety, pain, coffee, smoking, hypoxiaExercise, fever, anxiety, pain, coffee, smoking, hypoxia Beta adrenergic drugsBeta adrenergic drugs

• Treatment: OXYGEN… Then, focus on underlying causeTreatment: OXYGEN… Then, focus on underlying cause

• Additional Treatment: Vagal StimulationAdditional Treatment: Vagal Stimulation

• =_____________________________________=_____________________________________

A rapid heart rate __________________________A rapid heart rate __________________________

____________________________________________________________________________________


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Abnormal Sinus RhythmsAbnormal Sinus RhythmsTachycardiaTachycardia


Fig. 18-17

Heart Rate _______

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Abnormal Sinus RhythmsAbnormal Sinus RhythmsBradycardiaBradycardia

BradycardiaBradycardia Sinus bradycardiaSinus bradycardia

• HR <60 beats/minHR <60 beats/min

• Regular and rhythmicRegular and rhythmic

• Normal in sleep, physically conditioned individualsNormal in sleep, physically conditioned individuals

• Carotid sinus syndrome; overly sensitive pressure Carotid sinus syndrome; overly sensitive pressure receptors (vagal) in the neck… If stimulated = syncopereceptors (vagal) in the neck… If stimulated = syncope

• SYNCOPE = _________________SYNCOPE = _________________

• Gagging can also cause bradycardia (Suctioning)Gagging can also cause bradycardia (Suctioning)

• Symptomatic bradycardiaSymptomatic bradycardia hypotension, weakness, sweating, syncopehypotension, weakness, sweating, syncope

• Treatment: atropine; pacemakerTreatment: atropine; pacemaker


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Abnormal Sinus RhythmsAbnormal Sinus RhythmsBradycardiaBradycardia


Fig. 18-18Heart Rate _______

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Sinus arrhythmiaSinus arrhythmia Irregularly generated sinus node impulsesIrregularly generated sinus node impulses Alternate between fast and slow ratesAlternate between fast and slow rates Irregular spacing between QRS complexesIrregular spacing between QRS complexes Follows inspiration & expiration (Follows inspiration & expiration (↑rate insp.; ↓exp.)↑rate insp.; ↓exp.) No clinical significance and do not require No clinical significance and do not require

treatmenttreatment


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Fig. 18-19

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Premature Atrial Contraction (PAC)Premature Atrial Contraction (PAC)

Ectopic focus fires = early atrial contractionEctopic focus fires = early atrial contraction QRS complexes are ____________ but QRS complexes are ____________ but

___________ ________________________ _____________

Stress, alcohol, tobacco, caffeine, electrolyte Stress, alcohol, tobacco, caffeine, electrolyte imbalances, sympathetic stimulationimbalances, sympathetic stimulation

Drugs: sodium & calcium channel inhibitors Drugs: sodium & calcium channel inhibitors may be used: quinidine: verapamilmay be used: quinidine: verapamil


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Premature Atrial Contraction (PAC)Premature Atrial Contraction (PAC)


Fig. 18-20

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Supraventricular ArrhythmiasSupraventricular Arrhythmias“Above the Ventricles”“Above the Ventricles”

Atrial flutterAtrial flutter Single ectopic pacemaker above AV nodeSingle ectopic pacemaker above AV node Ectopic focus produces F waves (saw-toothed)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-wavesAV node normally blocks transmission of many F-waves Atrial rate 200-350 bpm and regular; thus QRS rate is Atrial rate 200-350 bpm and regular; thus QRS rate is

regular, but slower than atrial rateregular, but slower than atrial rate Symptoms: palpitations, nervousness, anxiety, possible Symptoms: palpitations, nervousness, anxiety, possible

syncope if inadequate ventricular filling timesyncope if inadequate ventricular filling time Treatment: CaTreatment: Ca++++ blockers; electrical cardioversion blockers; electrical cardioversion

• Electrical Shock synchronized with heart rateElectrical Shock synchronized with heart rate


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Supraventricular ArrhythmiasSupraventricular ArrhythmiasA-FlutterA-Flutter


Fig. 18-21

Every 4th atrial impulse is transmitted to ventricles, producing a regular QRS rhythm.

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Supraventricular ArrhythmiasSupraventricular Arrhythmias

Atrial fibrillationAtrial fibrillation Multiple randomly firing ectopic atrial fociMultiple randomly firing ectopic atrial foci Atria “quiver” (Atria “quiver” (no pumpingno pumping) at 300-600 impulses/min; completely ) at 300-600 impulses/min; completely

irregularirregular Loss of atrial kickLoss of atrial kick = reduced ventricular filling = reduced ventricular filling→→ reduced stroke reduced stroke

volume & CO; occasional volume & CO; occasional peripheral pulse deficitperipheral pulse deficit Fine fibrillatory waves; slightly wavy baseline (no “Ps”)Fine fibrillatory waves; slightly wavy baseline (no “Ps”) Slower, irregular ventricular rateSlower, irregular ventricular rate Causes: conditions that Causes: conditions that ↑↑ atrial pressure & enlarge atria: longer atrial pressure & enlarge atria: longer

depolarization routedepolarization route May cause hypotension, fainting (syncope)May cause hypotension, fainting (syncope) Pooling of blood in atria: Pooling of blood in atria: thromboembolism risk: thromboembolism risk: anticoagulant anticoagulant

drugsdrugs important preventative treatment important preventative treatment Treatment: CaTreatment: Ca++++ blockers; electrical cardioversion blockers; electrical cardioversion


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Supraventricular ArrhythmiasSupraventricular ArrhythmiasA-FibA-Fib


Fig. 18-22

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Junctional ArrhythmiasJunctional Arrhythmias

AV node assumes role of pacemakerAV node assumes role of pacemaker Junctional escape rhythmJunctional escape rhythm if SA node fails to fire if SA node fails to fire Inherent rate of 40 to 60 bpmInherent rate of 40 to 60 bpm QRS normal shape and durationQRS normal shape and duration Retrograde (backward) atrial conductionRetrograde (backward) atrial conduction

Inverted, hidden, or retrograde P waves (after QRS)Inverted, hidden, or retrograde P waves (after QRS) Irritable junctional fibers cause PJCIrritable junctional fibers cause PJC Junctional tachycardiasJunctional tachycardias

Paroxysmal Paroxysmal (PSVT): up to 240/min (caffeine, nicotine, alcohol, (PSVT): up to 240/min (caffeine, nicotine, alcohol, overexertion, electrolyte imbalance, etc.)overexertion, electrolyte imbalance, etc.)

Nonparoxysmal Nonparoxysmal (150/min): (150/min): ↑junctional excitability (drug toxicity)↑junctional excitability (drug toxicity) Treatment: Treatment: vagal stimulation; IV adenosine; IV Cavagal stimulation; IV adenosine; IV Ca++++ blocker blocker


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ConceptQuestion 18-4ConceptQuestion 18-4

Why do chronic congestive heart failure and Why do chronic congestive heart failure and high atrial pressures predispose a person to high atrial pressures predispose a person to the development of atrial fibrillation?the development of atrial fibrillation?

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Junctional ArrhythmiasJunctional Arrhythmias


Fig. 18-24

Inverted P waves; slow heart rate

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Junctional ArrhythmiasJunctional ArrhythmiasJunctional TachycardiaJunctional Tachycardia


Fig. 18-25

No P waves

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Ventricular ArrhythmiasVentricular Arrhythmias Premature ventricular contraction (PVC)Premature ventricular contraction (PVC)

Ectopic focus/excitability arises from ventriclesEctopic focus/excitability arises from ventricles QRS not preceded by P waveQRS not preceded by P wave Wide (>0.12 sec) and bizarre appearanceWide (>0.12 sec) and bizarre appearance Generate T wave of opposite polarity (downward)Generate T wave of opposite polarity (downward)

Followed by compensatory pauseFollowed by compensatory pause Frequent PVCs signal life-threatening arrhythmia potential; highly Frequent PVCs signal life-threatening arrhythmia potential; highly

irritable ventricular muscle fibersirritable ventricular muscle fibers Unifocal vs. multifocal PVCsUnifocal vs. multifocal PVCs BigeminyBigeminy Treatment: Treatment: antiarrhythmic drug: antiarrhythmic drug: lidocainelidocaine OXYGEN!OXYGEN!


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Ventricular ArrhythmiasVentricular Arrhythmias


Fig. 18-26Unifocal PVCs

Multifocal PVCs: serious ventricular irritability

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Ventricular ArrhythmiasVentricular Arrhythmias Ventricular tachycardia (V-Tach)Ventricular tachycardia (V-Tach)

Successive “runs” of PVCsSuccessive “runs” of PVCs Rate of 110-250/minRate of 110-250/min Treat as emergency: serious sign of ventricular Treat as emergency: serious sign of ventricular

irritabilityirritability QRS complexes bizarre and wideQRS complexes bizarre and wide High potential to progress to ventricular fibrillationHigh potential to progress to ventricular fibrillation Treat with Treat with IV lidocaine or amiodaroneIV lidocaine or amiodarone CardioversionCardioversion


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Ventricular TachycardiaVentricular Tachycardia


Fig. 18-28

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Ventricular ArrhythmiasVentricular Arrhythmias Ventricular fibrillation (VF)Ventricular fibrillation (VF)

Most lethal arrhythmia = Most lethal arrhythmia = cardiac arrest;cardiac arrest; CODE BLUECODE BLUE Ventricles nonfunctional, quivering, no pumping abilityVentricles nonfunctional, quivering, no pumping ability No recognizable waves or complexesNo recognizable waves or complexes Requires electrical defibrillationRequires electrical defibrillation—no drug can convert to —no drug can convert to

normal rhythmnormal rhythm Equivalent to Cardiac Arrest. CPR must be initiatedEquivalent to Cardiac Arrest. CPR must be initiated

SHOCKABLE RHYTHMSHOCKABLE RHYTHM

Along with a shock, use:Along with a shock, use:

• Epinephrine, Amiodarone, LidocaineEpinephrine, Amiodarone, LidocaineCopyright © 2007, 1998 by Mosby, Inc., an affiliate of Elsevier Inc.

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Ventricular FibrillationVentricular Fibrillation


Fig. 18-29

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ASYSTOLEASYSTOLE

1 lecture notes chapter 18 electrocardiogram and cardiac arrhythmias copyright © 2007, 1998 by...

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