12-Lead 12-Lead ElectrocardiographyElectrocardiography

a comprehensive course

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

Morphologi

es

(The “P”)

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

Intervals & MorphologyIntervals & Morphology

• 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 BBBLearn how to identify BBB’’s.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.

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-WaveP-Wave

• Left Atrial EnlargementLeft Atrial Enlargement– P-MitraleP-Mitrale

• 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.

V1

II

LAE

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 BacchmannDelay in Bacchmann’’s s

bundlebundle

PR-IntervalPR-Interval

• < 200 ms< 200 ms

• > 120 ms> 120 ms

PR-IntervalPR-Interval

• 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

ConductionConduction

WPWWPW

Shortened PR-Interval

Widened QRS

Delta Wave

WPWWPW Antidromic Antidromic

ConductionConduction

WPWWPW

WPWWPW

WPWWPW

WPWWPW

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.

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.

The End

Next up – The QRS complex