Basic ECGBasic ECG

ObjectivesObjectives

Identify the functions of the electrical Identify the functions of the electrical conduction system of the heart. conduction system of the heart.

Demonstrate accurate ECG rhythm Demonstrate accurate ECG rhythm interpretation.interpretation.

Identify key characteristics of normal Identify key characteristics of normal and abnormal rhythms.and abnormal rhythms.

Sinoatrial NodeSinoatrial Node(SA Node)(SA Node)

Located in RA near SVCLocated in RA near SVC Normal pacemaker of heartNormal pacemaker of heart Initiates an impulseInitiates an impulse Intrinsic rate of 60-100Intrinsic rate of 60-100

Intra-Atrial PathwaysIntra-Atrial Pathways Located in atrial tissue between SA & Located in atrial tissue between SA &

AV nodesAV nodes Conducts impulse from SA Conducts impulse from SA atrial atrial

musculature musculature AV node AV node Anterior, middle, and posterior tractsAnterior, middle, and posterior tracts

Atrioventricular NodeAtrioventricular Node(AV Node)(AV Node)

Located near tricuspid valveLocated near tricuspid valve Delays impulse from atriaDelays impulse from atria Allows for ventricular fillingAllows for ventricular filling Protective mechanism against rapid Protective mechanism against rapid

supraventricular impulsessupraventricular impulses

Junctional TissueJunctional Tissue Tissue in lower AV nodeTissue in lower AV node Back-up pacemakerBack-up pacemaker Intrinsic rate of 40-60Intrinsic rate of 40-60

Bundle of His & R & L Bundle of His & R & L Bundle BranchesBundle Branches

Bundle of His connects AV node to Bundle of His connects AV node to

Right & Left bundle branchesRight & Left bundle branches R bundle carries impulse to RVR bundle carries impulse to RV L bundle carries impulse to LVL bundle carries impulse to LV

Ventricular TissueVentricular Tissue Back-up pacemakerBack-up pacemaker Intrinsic rate 20-40Intrinsic rate 20-40

Purkinje SystemPurkinje System

Distal to the bundle branchesDistal to the bundle branches Rapidly conducts impulses to Rapidly conducts impulses to

ventricular subendocardial ventricular subendocardial layerslayers

ECG PaperECG Paper Horizontal axis represents timeHorizontal axis represents time

small box = 0.04 secondssmall box = 0.04 seconds 5 small boxes = 1 large block = 0.20 5 small boxes = 1 large block = 0.20

secondsseconds 5 large boxes = 1 second5 large boxes = 1 second Normal strip = 30 large boxes = 6 Normal strip = 30 large boxes = 6

secondsseconds

ECG Paper cont...ECG Paper cont... Vertical axis measures:Vertical axis measures:

amplitude in millimeters (mm)amplitude in millimeters (mm) electrical voltage in millivolts (mV)electrical voltage in millivolts (mV) 1 small block = 1 mm or 0.1 mV1 small block = 1 mm or 0.1 mV 1 large block = 5 mm or 0.5 mV1 large block = 5 mm or 0.5 mV

TerminologyTerminology

DepolarizationDepolarization– The electrical activation of a cardiac cellThe electrical activation of a cardiac cell

RepolarizationRepolarizationElectrical recovery of the cardiac cellElectrical recovery of the cardiac cell

The P WaveThe P Wave Atrial depolarization Atrial depolarization Characteristics:Characteristics:

precedes the QRSprecedes the QRS 2-3 mm high2-3 mm high 0.06-0.12 seconds0.06-0.12 seconds round & uprightround & upright

QRS ComplexQRS Complex Ventricular Ventricular

depolarization depolarization Characteristics:Characteristics:

follows PR follows PR intervalinterval

< 0.12 seconds < 0.12 seconds

T WaveT Wave Ventricular Ventricular

repolarization repolarization

Characteristics:Characteristics: follows S wavefollows S wave round & smoothround & smooth

PR IntervalPR Interval Atrial impulse to Atrial impulse to

the AV node-the AV node-bundle of His-R & L bundle of His-R & L bundlesbundles

Characteristics:Characteristics: beginning of P wave to beginning of P wave to

beginning of QRS beginning of QRS complexcomplex

0.12-0.20 seconds0.12-0.20 seconds

ST SegmentST Segment Early Ventricular Early Ventricular

Repolarization Repolarization Characteristics:Characteristics:

from end of QRS from end of QRS complex to complex to beginning of T wavebeginning of T wave

QT IntervalQT Interval Ventricular Ventricular

depolarization & depolarization & repolarizationrepolarization

Characteristics:Characteristics: beginning of QRS beginning of QRS

to end of T waveto end of T wave 0.35 to 0.45 0.35 to 0.45

secondsseconds

MonitoringMonitoringFive leadsFive leads

Electrodes & LeadsElectrodes & Leads Electrodes measure the direction of Electrodes measure the direction of

electrical currentelectrical current The current is transformed into The current is transformed into

waveformswaveforms The ECG records the waveform The ECG records the waveform

information from different views & information from different views & leadsleads

LeadsLeads Provide different views of the Provide different views of the

heart’s electrical activityheart’s electrical activity

LeadLead view between a + pole & a - poleview between a + pole & a - pole the axis refers to the direction of the current the axis refers to the direction of the current

moving through the heartmoving through the heart direction of the waveform on the ECGdirection of the waveform on the ECG

Lead SelectionLead Selection

Based on patient historyBased on patient history

Calculation of Heart Calculation of Heart RatesRates

R-R….. SMALL BOXES….. DIVIDE into 1500R-R….. SMALL BOXES….. DIVIDE into 1500

6 SECOND METHOD6 SECOND METHOD

RATE CHARTRATE CHART

Determine the RateDetermine the Rate 1,500 method1,500 method

use with regular rhythms, most accurateuse with regular rhythms, most accurate 1,500 small squares = 1 minute1,500 small squares = 1 minute count small squares between 2 consecutive P wavescount small squares between 2 consecutive P waves divide into 1,500 to get atrial rate (1500/30 = 50 bpm)divide into 1,500 to get atrial rate (1500/30 = 50 bpm) count small squares between 2 consecutive R wavescount small squares between 2 consecutive R waves divide into 1,500 to get ventricular ratedivide into 1,500 to get ventricular rate

Determine the Rate Determine the Rate cont..cont..

6 Second method6 Second method good method if rhythm is irregulargood method if rhythm is irregular

use a 6 second stripuse a 6 second strip count the number of P waves for the atrial rate and count the number of P waves for the atrial rate and

multiply by 10multiply by 10 count the number of R waves for the ventricular rate count the number of R waves for the ventricular rate

and multiply by 10and multiply by 10

Determine the Rate Determine the Rate cont...cont...

Sequence method-memorization of: Sequence method-memorization of: 300-150-100-75-60-50-43300-150-100-75-60-50-43

for atrial rate, locate a P wave on a heavy black for atrial rate, locate a P wave on a heavy black lineline

assign the next heavy black line 300 & begin assign the next heavy black line 300 & begin counting backwards until you reach the next P counting backwards until you reach the next P wavewave

for ventricular rate, repeat the same sequencefor ventricular rate, repeat the same sequence

ECG - HOW TO READ IT?ECG - HOW TO READ IT?CHECK THE ATRIAL and VENTRICULAR RHYTHMCHECK THE ATRIAL and VENTRICULAR RHYTHM

Is it REGULAR OR IRREGULAR?Is it REGULAR OR IRREGULAR?

CALCULATE THE ATRIAL AND VENTRICULAR RATECALCULATE THE ATRIAL AND VENTRICULAR RATESame or different?Same or different?

LOOK FOR P, Q, R, S, AND TLOOK FOR P, Q, R, S, AND TIs there a P wave for every QRS?Is there a P wave for every QRS?

Is there a QRS for every P?Is there a QRS for every P?

PR Interval? QRS width?PR Interval? QRS width?

FIND THE ORIGINFIND THE ORIGINSinus, Atrial, Junctional, or Ventricular?Sinus, Atrial, Junctional, or Ventricular?

KNOW THE MECHANISMKNOW THE MECHANISMFast, slow, premature, late, fib, flutter or blocked, pacedFast, slow, premature, late, fib, flutter or blocked, paced

Measure the PR Measure the PR IntervalInterval

Is the duration 0.12-0.20 seconds?Is the duration 0.12-0.20 seconds? Is the interval consistent?Is the interval consistent?

Measure the Duration Measure the Duration of the QRS Complexof the QRS Complex Is the duration < 0.12 seconds?Is the duration < 0.12 seconds? Are all of the complexes the same Are all of the complexes the same

size & shape?size & shape? Is there a QRS after each P wave?Is there a QRS after each P wave?

CheckpointCheckpoint1.1. The ECG provides information about:The ECG provides information about:

a.a. the contractility of the heartthe contractility of the heart

b.b. the electrical activity of the heartthe electrical activity of the heart

c. c. cardiac output and resistancecardiac output and resistance

d.d. all of the aboveall of the above

2.2. In the electrocardiogram, the QRS represents:In the electrocardiogram, the QRS represents:

a. ventricular contractiona. ventricular contraction

b. atrial contractionb. atrial contraction

c. ventricular depolarizationc. ventricular depolarization

d. discharge of impulse from the sinus noded. discharge of impulse from the sinus node

3.3. Indicate the intrinsic rate of the following:Indicate the intrinsic rate of the following:

Sinus node Sinus node

Junctional tissue Junctional tissue ______________

Ventricular tissue Ventricular tissue

Sinus RhythmsSinus Rhythms

Normal Sinus Rhythms (NSR)Normal Sinus Rhythms (NSR) Sinus Tachycardia (ST)Sinus Tachycardia (ST) Sinus Bradycardia (SB)Sinus Bradycardia (SB) Sinus Dysrhythmia (SD)Sinus Dysrhythmia (SD) Sinus Pause (Sinus Arrest)Sinus Pause (Sinus Arrest)

Normal Sinus RhythmNormal Sinus Rhythm

The SA node (normal Pacemaker) of the heart is in The SA node (normal Pacemaker) of the heart is in controlcontrol

RhythmRhythm: Regular: Regular Rate:Rate: 60-100/min 60-100/min

P WaveP Wave Precedes each QRS, normal. Precedes each QRS, normal.

PR:PR: 0.12-0.20Sec 0.12-0.20Sec QRS:QRS: < 0.12 sec & Constant < 0.12 sec & Constant

Sinus TachycardiaSinus TachycardiaSA node fires faster than 100/minSA node fires faster than 100/min

Rhythm:Rhythm: Regular Regular Rate:Rate: 100-160/min 100-160/min

P Wave:P Wave: Normal, precedes each QRS Normal, precedes each QRS

PR:PR: 0.12 - 0.20 sec 0.12 - 0.20 sec QRS:QRS: <0.12 sec <0.12 sec

Sinus TachycardiaSinus TachycardiaCauses:Causes:

* Anemia, Hypoxia, Hypovolemia, * Anemia, Hypoxia, Hypovolemia, HypotensionHypotension

* Exercise, Emotion, Anxiety, Pain* Exercise, Emotion, Anxiety, Pain

* Fever* Fever

* Drug related-Caffeine, Epinephrine, Cocaine* Drug related-Caffeine, Epinephrine, Cocaine

* Early sign of CHF* Early sign of CHF

* Theophylline toxicity* Theophylline toxicity

* Hyperthyroidism* Hyperthyroidism

Management:Management:

* Assess for cause & treat it* Assess for cause & treat it

* Beta Blockers for primary tachycardia* Beta Blockers for primary tachycardia

Sinus BradycardiaSinus Bradycardia

SA Node fires slower than 60/minSA Node fires slower than 60/min

Rhythm:Rhythm: Regular Regular Rate:Rate: < 60/min < 60/min

P Wave:P Wave: normal, precedes each QRS normal, precedes each QRS

PR:PR: 0.12 - 0.20 sec 0.12 - 0.20 sec QRS:QRS: < 0.12 sec < 0.12 sec

Sinus Bradycardia

CausesCauses Normal in healthy, Normal in healthy,

young, athletesyoung, athletes Vagal stimulation… MI, Vagal stimulation… MI,

Vomiting, Straining at Vomiting, Straining at stool, Pharyngeal stool, Pharyngeal suctioningsuctioning

Drug effect… Beta Drug effect… Beta blockersblockers

Increased ICPIncreased ICP HypokalemiaHypokalemia Sick Sinus syndromeSick Sinus syndrome

SignificanceSignificance If severe or prolonged, If severe or prolonged,

may cause decrease in may cause decrease in cardiac output and cardiac output and syncopesyncope

At risk for escape rhythm At risk for escape rhythm and or premature beats and or premature beats to gain control due to to gain control due to long pauseslong pauses

Sinus Bradycardia Interventions

Assess patient

Hold digoxin, if digoxin toxicity

Relieve source of vagal stimulation, if possible (treat nausea, shorten periods of suctioning, no valsalvas)May need to adjust drug regimen

If symptomatic, treat with Atropine

May require temporary pacemaker

Sinus Dysrhythmia Sinus Dysrhythmia (Sinus Arrhythmia)(Sinus Arrhythmia)

Irregular heart rate; Sinus node in charge;Irregular heart rate; Sinus node in charge;

usually varies with respiratory cycleusually varies with respiratory cycle

Rhythm :Rhythm : IrregularIrregular Rate :Rate : 60 - 10060 - 100

P wave :P wave : Normal Normal PR : PR : NormalNormal QRS:QRS: Normal Normal

The longest R-R interval - the shortest R-R intervalThe longest R-R interval - the shortest R-R interval = > 0.12 seconds= > 0.12 seconds

Sinus DysrhythmiaSinus DysrhythmiaSignificance: Usually none

Causes:Common in children & outgrown in teensVariation of Sinus rhythmVagal stimulation

Treatment:Usually noneR/O more serious irregular rhythmMinimize vagal stimulation

Sinus Pause (Arrest)Sinus Pause (Arrest)Sinus node fails to generate an impulse for one or Sinus node fails to generate an impulse for one or

more beats; usually reset by sinus node but more beats; usually reset by sinus node but escape beats/rhythms may occurescape beats/rhythms may occur

Rhythm:Rhythm: Regular except for pause Regular except for pause PR:PR: normal normal

Rate:Rate: depends on underlying rhythm depends on underlying rhythm QRS:QRS: normal normal

No PNo P wave preceding pause wave preceding pause

Sinus PauseSinus PauseCAUSES May decrease

CO Duration of

pause determines the seriousness

of dysrhythmia

SIGNIFICANCEVagal stimulationSick Sinus syndromeDig. ToxicityBeta blockersCa channel blockersIschemia of SA

nodePericarditisHyperkalemaAmiodarone

INTERVENTIONSTreat causeAtropine for acute bradycardiaIf asleep, wake

the patientPause over 3 seconds… Evaluation for a

pacemaker (External or permanent)

CheckpointCheckpoint

True or FalseTrue or False1.1. Sinus dysrhythmia is dangerous and requires immediate Sinus dysrhythmia is dangerous and requires immediate

intervention.intervention.

2.2. The treatment of choice for sinus tachycardia is related to The treatment of choice for sinus tachycardia is related to the cause.the cause.

3.3. Sinus dysrhythmia is characterized by a slowing and Sinus dysrhythmia is characterized by a slowing and speeding of the rate.speeding of the rate.

4.4. The first nursing action in relation to a rhythm disturbance The first nursing action in relation to a rhythm disturbance is to check the patient and assess level of consciousness.is to check the patient and assess level of consciousness.

Atrial RhythmsAtrial Rhythms

Premature Atrial Complex (PAC)Premature Atrial Complex (PAC) Supraventricular Tachycardia (SVT)Supraventricular Tachycardia (SVT) Atrial FlutterAtrial Flutter Atrial FibrillationAtrial Fibrillation

Premature Atrial ComplexesPremature Atrial Complexes Originates outside the SA nodeOriginates outside the SA node Single or multiple ectopic focusSingle or multiple ectopic focus Various shapes of P wavesVarious shapes of P waves PR - normal; QRS - normalPR - normal; QRS - normal

PACsPACsSignificance Cause Interventions

Usually not serious In pts. with heart disease… more serious In MI … early sign of CHF

Common Emotional stress Alcohol, caffeine, tobacco Electrolyte imbalance Hypoxia Digoxin toxicity Hyperthyroidism CV disease

Drugs

Infrequent … No treatment Eliminate cause Drugs

SVTSVT

ABSOLUTELY REGULAR RHYTHM !ABSOLUTELY REGULAR RHYTHM !

USUALLY OCCURS SUDDENLYUSUALLY OCCURS SUDDENLY

RATE: 160-240/minRATE: 160-240/min

P WAVE: MAY NOT BE SEENP WAVE: MAY NOT BE SEEN

PR : NOT MEASURABLEPR : NOT MEASURABLE

QRS: NORMALQRS: NORMAL

Significance - SVTSignificance - SVT •If rapid, can decrease cardiac If rapid, can decrease cardiac outputoutput

•Can causeCan cause•anxietyanxiety•anginaangina•palpitationspalpitations•shortness of breathshortness of breath•decreased level of consciousnessdecreased level of consciousness•decreased BPdecreased BP•shockshock•pulmonary congestionpulmonary congestion•CHFCHF•acute MIacute MI

Causes - SVTCauses - SVT

NORMAL CARDIAC OTHER

Caffeine Recreational drugs Electrolyte imbalance Hypoxia Physical & psychological Stress

MI Cardiomyopathy WPW syndrome Sick-Sinus syndrome

Corpulmonale (COPD) Hyperthyroidism Dig. Toxicity

INTERVENTI ONS Check Digoxin Level Valsalva Maneuver

Carotid sinus massage – physicians only Drugs – Adenosine (drug of choice)

Drugs – Verapamil, Diltiazem, Oxygen; check ABG if needed

Cardioversion Patient education – stress management

Carotid MassageCarotid Massage

By MDs onlyBy MDs only!!

Both diagnose & terminate PSVTBoth diagnose & terminate PSVT

Auscultate first for bruitAuscultate first for bruit

Never compress Never compress

both carotidsboth carotids

simultaneously!simultaneously!

CardioversionCardioversionSynchronized cardioversion delivers Synchronized cardioversion delivers

electrical stimulus during depolarization - electrical stimulus during depolarization - depolarizes all cells simultaneously, depolarizes all cells simultaneously,

allowing SA node to resume the allowing SA node to resume the pacemaker rolepacemaker role

QRS complex must be present QRS complex must be present

Usually electiveUsually elective

Potassium, digoxin level,emergency Potassium, digoxin level,emergency equipment,O2, NPO, IV, TEE, Sedationequipment,O2, NPO, IV, TEE, Sedation

Supraventricular Tachycardia vs.

Sinus Tachycardia

SVT ST

Begins abruptly with asingle PAC or PJC.

Rate: 160 –240

Can be terminated with avagal maneuver.

Begins more slowly inresponse to a physiologicneed.

Rate usually does notexceed 160.

Unaffected or onlymomentarily slowed downby a vagal maneuver

Atrial FlutterAtrial Flutter Atrial rate of 250 - 350 beats / minAtrial rate of 250 - 350 beats / min Originating from a single ectopic Originating from a single ectopic

focusfocus Saw toothed F wavesSaw toothed F waves AV node delays the impulses at AV node delays the impulses at

various ratiosvarious ratios

Atrial FlutterAtrial FlutterCAUSE SIGNIFICANCE INTERVENTION

Conditions that enlarge atrium and elevate atrial pressures

- mitral valve disease - hyperthyroidism - primary myocardial

disease - pericardial disease

Seen in pts with MI, COPD, & hypoxia Occasionally Digoxin toxicity Rare in healthy people

- peripheral & apical pulses are normal

- s/s low cardiac out put if

ventricular rate is high (loss of atrial kick)

- Less stable than A.Fib

- Take a second look at

sinus tachycardia > 150/mt – may be 2:1 conduction!

- More clinical attention

needed in pts with ischemic heart disease

- Assess the pt. - Carotid massage by

MD only (temporary) - Cardioversion

- Drug therapy –

Digoxin, Verapamil, Ibutilide, Diltiazem, beta blockers

- Anticoagulation

Atrial FibrillationAtrial Fibrillation Chaotic, asynchronous electrical activity of Chaotic, asynchronous electrical activity of

atrial tissue atrial tissue

Irregularly irregular rhythmIrregularly irregular rhythm

Rate - 400/min or moreRate - 400/min or more

No distinct P waves - wavy deflection - f No distinct P waves - wavy deflection - f waveswaves

No PR intervalNo PR interval

QRS - normal: ventricular response can be QRS - normal: ventricular response can be rapid, controlled or slowrapid, controlled or slow

Radial & Apical pulse rates may varyRadial & Apical pulse rates may vary

Significance of Atrial Significance of Atrial FibrillationFibrillation

SymptomsSymptomsPalpitation, Pulse deficit, Irregular pulsePalpitation, Pulse deficit, Irregular pulse

Hemodynamic compromiseHemodynamic compromiseLoss of atrial kick ; less ventricular fillingLoss of atrial kick ; less ventricular filling

Low CO - hypotension, syncope, low outputLow CO - hypotension, syncope, low output

S/S heart failureS/S heart failure

Increased risk of Increased risk of thromboembolismthromboembolism

Atrial Fibrillation-CausesAtrial Fibrillation-Causes

HypertensionHypertension

Valvular heart diseaseValvular heart disease

HyperthyroidismHyperthyroidism

CADCAD

Acute MIAcute MI

PericarditisPericarditis

HypoxiaHypoxia

ASDASD

A FIB – InterventionsA FIB – InterventionsControl ventricular responseControl ventricular response

Anticoagulation to prevent embolusAnticoagulation to prevent embolusreturn to sinus rhythmreturn to sinus rhythm

Acute– Medications

Beta Blockers Ca Channel Blockers

– Cardioversion– Anti-coagulation

Subacute– Treat Reversible Causes– Cardioversion– Anticoagulation

ChronicChronic– MedicationsMedications– AnticoagulationAnticoagulation– AblationAblation

CheckpointCheckpoint

1.1. Vagal stimulation which may alter the atrial rhythm Vagal stimulation which may alter the atrial rhythm includes which of the following:includes which of the following:

a.a. Rapid breathingRapid breathing

b.b. Lying downLying down

c.c. Carotid Sinus MassageCarotid Sinus Massage

d.d. Valsalva ManeuverValsalva Maneuver

2.2. Atrial fibrillation decreases cardiac output by which of the Atrial fibrillation decreases cardiac output by which of the following:following:

a.a. Decreasing filling timeDecreasing filling time

b.b. Loss of atrial kickLoss of atrial kick

c.c. Slowing ventricular rateSlowing ventricular rate

d.d. Causing Palpitations. Causing Palpitations.

Atrial Arrhythmias Atrial Arrhythmias Exercise #1Exercise #1

Atrial Arrhythmias

Exercise #2

Atrial Arrhythmias

EXERCISE #3

Atrial Arrhythmias Atrial Arrhythmias EXERCISE #4EXERCISE #4

Atrial Arrhythmia Atrial Arrhythmia Exercise #5Exercise #5

Atrial Arrhythmia Atrial Arrhythmia Exercise #6Exercise #6