12 lead-lesson 3

12-Lead 12-Lead ElectrocardiographyElectrocardiography

a comprehensive course

Adam Thompson, EMT-P, A.S.Adam Thompson, EMT-P, A.S.

Lesson

ResourcesResources

www.http://ecgpedia.org

The 6-Step MethodThe 6-Step Method

• 1. Rate & Rhythm1. Rate & Rhythm

• 2. Axis Determination2. Axis Determination

• 3. Intervals3. Intervals

• 4. Morphology4. Morphology

• 5. STE-Mimics5. STE-Mimics

• 6. Ischemia, Injury, & Infarct6. Ischemia, Injury, & Infarct

Lesson ThreeLesson Three

• Examining Intervals and MorphologiesExamining Intervals and Morphologies– Bundle Branch BlocksBundle Branch Blocks– WPWWPW– Chamber EnlargementChamber Enlargement– Hyperkalemia/HypokalemiaHyperkalemia/Hypokalemia– HypothermiaHypothermia– Long QT SyndromeLong QT Syndrome– Digitalis ToxicityDigitalis Toxicity

ObjectivesObjectives

• Review normal intervals & morphologiesReview normal intervals & morphologies• Learn how to identify BBB’s.Learn how to identify BBB’s.• Learn how to identify atrial enlargement or Learn how to identify atrial enlargement or

ventricular hypertrophy.ventricular hypertrophy.• Learn how to identify WPW or LGL.Learn how to identify WPW or LGL.• Learn how to identify electrolyte Learn how to identify electrolyte

derangements.derangements.

PR-IntervalPR-Interval

• PR-IntervalPR-Interval– > 120ms> 120ms– < 200ms< 200ms

P-WaveP-Wave

• Normal height < 2.5mm (2 1/2 small boxes)Normal height < 2.5mm (2 1/2 small boxes)• Normal width < 0.10 seconds (2 1/2 small boxesNormal width < 0.10 seconds (2 1/2 small boxes

P-WaveP-Wave

• P-MitraleP-Mitrale– Indicates left atrial Indicates left atrial

enlargement.enlargement.– A notched P-wave gretaer A notched P-wave gretaer

than 0.12 seconds.than 0.12 seconds.– A biphasic P-wave in V1 that A biphasic P-wave in V1 that

is deeper than it is tall.is deeper than it is tall.

P-Mitrale

P-WaveP-Wave

• P-PulmonaleP-Pulmonale– Indicates right atrial Indicates right atrial

enlargementenlargement– Peaked P-wave in limb leadsPeaked P-wave in limb leads

• Taller than 2.5mm (2 1/2 boxes)Taller than 2.5mm (2 1/2 boxes)

P-WaveP-Wave

• Intra-atrial conduction Intra-atrial conduction delaydelay– In V1In V1– Taller than it is deepTaller than it is deep– Delay in Bacchmann’s Delay in Bacchmann’s

bundlebundle

• < 200 ms< 200 ms

• > 120 ms> 120 ms

• PR-ElevationPR-Elevation– Usually indicates poor Usually indicates poor

baselinebaseline

• PR-DepressionPR-Depression– May indicate pericarditisMay indicate pericarditis– May indicate atrial May indicate atrial

infarctioninfarction

Short PR-IntervalShort PR-Interval

• Accessory PathwayAccessory Pathway– Bypasses AV nodeBypasses AV node– Predisposes patients to significant re-entry Predisposes patients to significant re-entry

tachycardias. tachycardias.

Accessory PathwayAccessory Pathway

• Wolff-Parkinson-White Syndrome (WPW)Wolff-Parkinson-White Syndrome (WPW)– Bundle of KentBundle of Kent– Short PR-IntervalShort PR-Interval– Delta Wave, Wide QRSDelta Wave, Wide QRS

• Lown-Ganong-Levine Syndrome (LGL)Lown-Ganong-Levine Syndrome (LGL)– James FiberJames Fiber– Short PR-IntervalShort PR-Interval– Normal P-wave, Normal QRSNormal P-wave, Normal QRS

WPWWPW

Bundle of KentBundle of Kent

WPWWPW

• Three conduction patternsThree conduction patterns– Physiological - Normal conduction, no changes may Physiological - Normal conduction, no changes may

be noted on 12-Leadbe noted on 12-Lead– Orthodromic - Signal travels down Kent bundle and Orthodromic - Signal travels down Kent bundle and

physiological pathway. physiological pathway. • Causes shortened PR-Interval & Delta Wave.Causes shortened PR-Interval & Delta Wave.

– Antidromic - From SA Node through Kent bundle to Antidromic - From SA Node through Kent bundle to ventricles then back to atrium via AV junction. ventricles then back to atrium via AV junction.

• Causes very fast wide complex tachycardias. Causes very fast wide complex tachycardias. • Looks like V-tach.Looks like V-tach.

WPWWPW Physiological Physiological

ConductionConduction

WPWWPW Orthodromic Orthodromic

WPWWPW

Shortened PR-Interval

Widened QRS

Delta Wave

WPWWPW Antidromic Antidromic

WPWWPW

• Fast, Broad, & Irregular (FBI)Fast, Broad, & Irregular (FBI)– Tachycardic, Wide QRS, Irregular rhythmTachycardic, Wide QRS, Irregular rhythm– Atrial Fibrillation with WPWAtrial Fibrillation with WPW– Atrial Fibrillation with BBBAtrial Fibrillation with BBB

• Always suspect WPW until proven otherwise!Always suspect WPW until proven otherwise!

WPWWPW

Fast, Broad, & IrregularFast, Broad, & Irregular

LGLLGL

Lown-Ganong-Levine Syndrome (LGL)Lown-Ganong-Levine Syndrome (LGL)» James Fiber bypasses the AV node. James Fiber bypasses the AV node. » Shortened PR-Interval.Shortened PR-Interval.

LGLLGL

QuickTime™ and a decompressor

are needed to see this picture.

Shortened PR-IntervalShortened PR-Interval

• The take home message:The take home message:– Recognizing the presence of an accessory Recognizing the presence of an accessory

pathway is much more important than the pathway is much more important than the ability to differentiate between the different ability to differentiate between the different types of accessory pathways. types of accessory pathways.

QRS ComplexQRS Complex

• Height & Morphology Height & Morphology will vary, depending on will vary, depending on the lead.the lead.

• Normal WidthNormal Width– > 0.10 seconds> 0.10 seconds– < 0.12 seconds< 0.12 seconds

• Much of our 12-Lead ECG interpretation Much of our 12-Lead ECG interpretation is going to be directly related to the is going to be directly related to the morphology of the QRS complex. morphology of the QRS complex.

• The morphology of the QRS complex The morphology of the QRS complex will assist us in identifying BBBs, V-will assist us in identifying BBBs, V-tach, LVH, RVH, and infarction.tach, LVH, RVH, and infarction.

QRS Complex

• Wide Complex Tachycardia (WCT)– Ventricular Tachycardia

• Josephson’s Sign– Notching of the downslope of S-Wave

• Brugada’s Sign– From behining of QRS to Nadir of S-Wave > 100ms

• QRS > 140ms

• Supraventricular Tachycardia (SVT)– Must have RBBB or LBBB pattern

QRS Complex

Josephson’s Sign

Bundle BranchesBundle Branches

Bundle Branch BlocksBundle Branch Blocks

• Right Bundle Branch Block (RBBB)Right Bundle Branch Block (RBBB)– The single right fascicle is blocked.The single right fascicle is blocked.

• Left Bundle Branch Block (LBBB)Left Bundle Branch Block (LBBB)– Both left fascicles are blocked.Both left fascicles are blocked.

• Non-Specific Intraventricular conduction delay (IVCD)Non-Specific Intraventricular conduction delay (IVCD)– BBB that doesn’t meet RBBB or LBBB criteria.BBB that doesn’t meet RBBB or LBBB criteria.

• May mimic an MIMay mimic an MI

• The side that is blocked conducts last The side that is blocked conducts last and takes longer.and takes longer.

• Normal Normal conduction conduction without a block.without a block. 1

Mean vector

Cardiac vector

• With a RBBB, the With a RBBB, the right fascicle is right fascicle is blocked, so the left blocked, so the left ventricle is ventricle is conducted first and conducted first and then the impulse then the impulse returns to the right.returns to the right.

• With a LBBB, the With a LBBB, the right ventricle is right ventricle is conducted first, conducted first, and the impulse and the impulse travels back to the travels back to the left.left.

J-Points

The J-point is the exact point where the QRS ends

= RBBB

= LBBB

Right Bundle Branch BlockRight Bundle Branch Block

• RBBB RBBB morphologiesmorphologies

• To properly differentiate between To properly differentiate between bundle branch blocks, you must also bundle branch blocks, you must also assess leads I and V6. assess leads I and V6.

• A slurred S-wave in leads I and V6 A slurred S-wave in leads I and V6 indicate a RBBB. indicate a RBBB.

I & V6

aVR V4

II aVL V2 V5

III aVF V3

Slurred S-Wave I & V6Slurred S-Wave I & V6

+ A B A

Mean vector moves towards positive electrode = positive QRSMean vector moves towards positive electrode = positive QRSMean vector moves away from positive electrode = negative QRSMean vector moves away from positive electrode = negative QRSMean vector is perpendicular to positive electrode = equiphasic QRSMean vector is perpendicular to positive electrode = equiphasic QRS

3I & V6I & V6

Left Bundle Branch BlockLeft Bundle Branch Block

• Duration greater than 0.12 secDuration greater than 0.12 sec

• Broad monomorphic R-wave in I & V6Broad monomorphic R-wave in I & V6

• Terminal S-wave in V1.Terminal S-wave in V1.

aVR V4

II aVL V2 V5

III aVF V3

Intraventricular Conduction Intraventricular Conduction DelayDelay

• A Non-specific IVCD is less common A Non-specific IVCD is less common than a RBBB or LBBBthan a RBBB or LBBB

• They are wide, atrial rhythms that They are wide, atrial rhythms that usually look like a left or right BBB in usually look like a left or right BBB in V1, but do not match the criteria in I & V1, but do not match the criteria in I & V6.V6.

Non-Specific IVCDNon-Specific IVCD

aVR V4

II aVL V2 V5

III aVF V3

III V1

Non-Specific IVCD

BBB ChartBBB Chart

RBBB LBBB IVCD

V1 TERMINAL

R-WAVE

TERMINAL

S-WAVE

TERMINAL

R/S-WAVE

I & V6 TERMINAL

S-WAVE

TERMINAL

R-WAVE

Anything is possible

Ventricular EnlargementVentricular Enlargement

• Left Ventricular Hypertrophy (LVH)Left Ventricular Hypertrophy (LVH)– The left ventricle is enlargedThe left ventricle is enlarged– Probably due to left-sided heart failureProbably due to left-sided heart failure

• Right Ventricular Hypertrophy (RVH)Right Ventricular Hypertrophy (RVH)– The right ventricle is enlargedThe right ventricle is enlarged– Probably due to right sided heart failureProbably due to right sided heart failure– May be due to pulmonary diseaseMay be due to pulmonary disease

Ventricular EnlargementVentricular Enlargement

• Left Ventricular Hypertrophy (LVH)Left Ventricular Hypertrophy (LVH)– May cause left axis deviationMay cause left axis deviation– May cause a left ventricular strain patternMay cause a left ventricular strain pattern

• Often mimics an anterior MIOften mimics an anterior MI

• Right Ventricular Hypertrophy (RVH)Right Ventricular Hypertrophy (RVH)– May cause right axis deviationMay cause right axis deviation– May cause a right ventrcular strain patternMay cause a right ventrcular strain pattern

• May mimic a inferior or posterior wall MIMay mimic a inferior or posterior wall MI

LVHLVH

RV LV Hypertrophy

Normal LVH

LVHLVH

• LVH CriteriaLVH Criteria– Large QRS complexesLarge QRS complexes

• Deepest S-wave in V1 or V2Deepest S-wave in V1 or V2• Tallest R-wave in V5 or V6Tallest R-wave in V5 or V6

– Add them togetherAdd them together» If the result is > 25mm = LVHIf the result is > 25mm = LVH

• Most texts may read: Most texts may read: – S-wave (V1/V2) + R-wave(V5/V6) > 35mmS-wave (V1/V2) + R-wave(V5/V6) > 35mm– However, tall R-waves and deep S-waves may However, tall R-waves and deep S-waves may

be cut off by the monitor. be cut off by the monitor. – Use the 25mm criteria and examine for “strain”Use the 25mm criteria and examine for “strain”

LVHLVH

V1 or V2V1 or V2

V5 or V6

LVHLVH

Lets take a look at an exampleLets take a look at an example

LVHLVH

14 + 15 = 29mm14 + 15 = 29mm

14mm 15mm

LVHLVH

• Since our total was 29mm, and a total of Since our total was 29mm, and a total of > 25mm meets LVH criteria, we can > 25mm meets LVH criteria, we can assume that this ECG is that of a assume that this ECG is that of a patient with LVH.patient with LVH.

*LVH may look a lot like a narrow LBBB.*LVH may look a lot like a narrow LBBB.

LVHLVH

• A wave that is A wave that is too tall or deep too tall or deep may be cut off may be cut off by the monitor by the monitor

• This is a This is a indicator of indicator of hypertrophyhypertrophy

LVHLVH

• A wave that is too tall A wave that is too tall or deep may be cut or deep may be cut off by the monitor off by the monitor

• This is a indicator of This is a indicator of hypertrophyhypertrophy

LVHLVH

Additional LVH CriteriaAdditional LVH Criteria

Any precordial lead

> 45mm

aVL > 11mm

Lead I > 12mm

aVF > 20mm

Ventricular LeadsVentricular Leads

Right Ventricular Left Ventricular

RVHRVH

• Right Ventricular HypertrophyRight Ventricular Hypertrophy– Criteria = R:S ration > 1 in V1/V2Criteria = R:S ration > 1 in V1/V2

• This means that the R-wave is bigger than the This means that the R-wave is bigger than the S-wave in V1 or V2.S-wave in V1 or V2.

• The QRS complex should be narrowThe QRS complex should be narrow• P-Pulmonale may be present.P-Pulmonale may be present.• Right axis deviation is common.Right axis deviation is common.

RVHRVHV1 or V2

V1/V2: R > S = RVH•QRS < 120ms (0.12 sec)

RVHRVH

Let’s take a look…Let’s take a look…

RVHRVH

Let’s take a look…Let’s take a look…

• Low VoltageLow Voltage– Chronic Cor PulmonaleChronic Cor Pulmonale

• Progressive lung disease, leading to right-sided heart Progressive lung disease, leading to right-sided heart failure.failure.

– Pericardial EffusionPericardial Effusion• Fluid in the pericardial sac.Fluid in the pericardial sac.

– Excessive ObesityExcessive Obesity

T WaveT Wave

• Should not be Should not be symmetrical.symmetrical.

• Should be upright in Should be upright in every lead but aVR.every lead but aVR.

• Height should Height should correlate with QRS.correlate with QRS.

• Should have a dull Should have a dull peak.peak.

Symmetrical T-WaveSymmetrical T-Wave

AsymmetricalNormal

SymmetricalAbnormal

HyperkalemiaHyperkalemia

• Hyperkalemia = High Potassium LevelHyperkalemia = High Potassium Level– Peaked T-WavesPeaked T-Waves

• May mimic an acute MIMay mimic an acute MI

– Sine WavesSine Waves• Sign of lethally high potassium levelSign of lethally high potassium level

Sine Wave

Peaked T-Wave

HyperkalemiaHyperkalemia

Hyperkalemia

T-Wave DiscordanceT-Wave Discordance

• Discordance means opposite.Discordance means opposite.– T-Wave discordance means that the T-T-Wave discordance means that the T-

Wave is deflected in the opposite direction Wave is deflected in the opposite direction as the terminal (last) wave of the QRS.as the terminal (last) wave of the QRS.

– T-Wave discordance is normal in every T-Wave discordance is normal in every lead with Left or Right BBBs.lead with Left or Right BBBs.

T-Wave DiscordanceT-Wave Discordance

Digitalis EffectDigitalis Effect

• Shortened QT intervalShortened QT interval• Characteristic down-sloping ST depressionCharacteristic down-sloping ST depression• DysrhythmiasDysrhythmias

– ventricular / atrial premature beatsventricular / atrial premature beats– paroxysmal atrial tachycardia with variable AV blockparoxysmal atrial tachycardia with variable AV block– ventricular tachycardia and fibrillationventricular tachycardia and fibrillation– many othersmany others

Digitalis EffectDigitalis Effect

QT-IntervalQT-Interval

Normal QTc Normal QTc

< 460 ms< 460 ms

Measures the time from when depolarization Measures the time from when depolarization starts to the end of repolarization.starts to the end of repolarization.

QTc = RR

Long QT SyndromeLong QT Syndrome

• QTc > 460msQTc > 460ms– CongenitalCongenital

• Major contributor to sudden unexplained death Major contributor to sudden unexplained death in children and young adults.in children and young adults.

– Drug inducedDrug induced• Caused by many arrhythmia medicationsCaused by many arrhythmia medications

U-WaveU-Wave

• Usually not Usually not visible.visible.

• Should not be Should not be prominent.prominent.

• Should never Should never be bigger than be bigger than T-waveT-wave

Osborn Waves

• Sometimes called “J-Waves”

• Indicates HYPOTHERMIA

• May be associated with bradycardia

• Extra wave at the J-Point of the QRS-complex.

Osborn Waves

Lesson 3

• This concludes lesson 3

• Practice examining different intervals & morphologies.

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