12-Lead 12-Lead ElectrocardiographyElectrocardiography

a comprehensive course

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

Intro

ResourceResource

Course ObjectivesCourse Objectives

•Learn the basic concept behind electrical vectors.Learn the basic concept behind electrical vectors.•Learn the 6 step process to 12-lead ECG interpretation.Learn the 6 step process to 12-lead ECG interpretation.•Learn how to identify chamber enlargement.Learn how to identify chamber enlargement.•Learn how to differentiate between atrial & ventricular Learn how to differentiate between atrial & ventricular rhythms.rhythms.•Learn how to identify bundle branch blocks.Learn how to identify bundle branch blocks.•Learn how to differentiate a STEMI from STE-MimicLearn how to differentiate a STEMI from STE-Mimic•Learn when to perform a right-sided or posterior 12-lead Learn when to perform a right-sided or posterior 12-lead ECG.ECG.

This IntroductionThis Introduction

• Learn the appropriate placement of the 12-Learn the appropriate placement of the 12-lead ECG electrodes.lead ECG electrodes.

• Learn how to eliminate artifact and obtain a Learn how to eliminate artifact and obtain a clean recording.clean recording.

• Learn the components of a 12-lead ECG stripLearn the components of a 12-lead ECG strip• Learn about the 6 step interpretation process.Learn about the 6 step interpretation process.

12-Lead ECG

“In lead II? You’ve got NO clue.” - Bob Page

12-Lead Placement12-Lead Placement

V1V1 - 4th ICS, right of - 4th ICS, right of sternumsternumV2V2 - 4th ICS, left of - 4th ICS, left of sternumsternumV3V3 - Between V2 & V4 - Between V2 & V4V4V4 - 5th ICS, left - 5th ICS, left midclavicular linemidclavicular lineV5V5 - Lateral to V4, left - Lateral to V4, left anterior axillary lineanterior axillary lineV6V6 - Lateral to V5, left - Lateral to V5, left midaxillary linemidaxillary line

V1V1 - 4th ICS, right of - 4th ICS, right of sternumsternumV2V2 - 4th ICS, left of - 4th ICS, left of sternumsternumV3V3 - Between V2 & V4 - Between V2 & V4V4V4 - 5th ICS, left - 5th ICS, left midclavicular linemidclavicular lineV5V5 - Lateral to V4, left - Lateral to V4, left anterior axillary lineanterior axillary lineV6V6 - Lateral to V5, left - Lateral to V5, left midaxillary linemidaxillary line

Eliminate ArtifactEliminate Artifact

• The patient’s chest should be bare.The patient’s chest should be bare.• All hair that inhibits adequate electrode All hair that inhibits adequate electrode

contact should be shaved.contact should be shaved.• Benzoin tincture may be used to Benzoin tincture may be used to

enhance adhesive.enhance adhesive.

The Culprit ElectrodeThe Culprit Electrode

• Precordial leads are easy. V1 has artifact? Precordial leads are easy. V1 has artifact? Check V1 electrode.Check V1 electrode.

• If Leads I & III have artifact, check left If Leads I & III have artifact, check left shoulder.shoulder.

• If Leads I & II have artifact, check right If Leads I & II have artifact, check right shoulder.shoulder.

• Leads II & III? Check left leg electrode.Leads II & III? Check left leg electrode.

12-Lead Basics

• Measurements are usually accurate

12-Lead Basics

• GE-Marquette 12SL Interpretive Algorhythm– Relatively reliable on clean ECG tracing.

12-Lead Basics

• The patient age and gender should always be entered into the 12-lead monitor.

12-Lead Basics

Typical 12-Lead ECG

12-Lead Basics

Typical 12-Lead ECG

12-Lead Basics

Typical 12-Lead ECG

12-Lead Basics

Typical 12-Lead ECG

12-Lead Basics

Typical 12-Lead ECG

Precordial LeadsPrecordial Leads

Precordium - area of chest over heartPrecordium - area of chest over heart

Limb LeadsLimb Leads

• Obtained from Red, White, Black, & Obtained from Red, White, Black, & Green electrodesGreen electrodes

Limb Leads Precordial Leads

Lead I aVR V1 V4

Lead II aVL V2 V5

Lead III aVF V3 V6

12 Leads12 Leads

Lead I aVR V1 V4

Lead II aVL V2 V5

Lead III aVF V3 V6

Contiguous LeadsContiguous Leads

Lead I

high lateral

aVR V1

septal

V4

anterior

Lead II

inferior

aVL

high lateral

V2

septal

V5

low lateral

Lead III

inferior

aVF

inferior

V3

anterior

V6

low lateral

Contiguous LeadsContiguous Leads

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

The 6-Step MethodThe 6-Step Method

Rate & RhythmRate & Rhythm

• What is your initial rhythm What is your initial rhythm interpretation?interpretation?

• Is the rhythm too fast or too slow?Is the rhythm too fast or too slow?• Are we certain it is supraventricular?Are we certain it is supraventricular?• If the QRS complexes are wide, it is If the QRS complexes are wide, it is

ventricular until proven otherwise.ventricular until proven otherwise.

The 6-Step MethodThe 6-Step Method

Axis DeterminationAxis Determination

• Is the axis normal?Is the axis normal?

• Is it left axis deviation? Is it left axis deviation?

• Is it right axis deviation?Is it right axis deviation?

• Extreme right axis deviation?Extreme right axis deviation?

• Consider pathologies!Consider pathologies!

The 6-Step MethodThe 6-Step Method

IntervalsIntervals

• Double check PR-interval and QRS Double check PR-interval and QRS durationduration

• Identify the QT or QTc intervalIdentify the QT or QTc interval

• Consider pathologies for abnormal Consider pathologies for abnormal intervals.intervals.

The 6-Step MethodThe 6-Step Method

MorphologyMorphology

• If QRS is wide, what is morphology in V1?If QRS is wide, what is morphology in V1?• Bundlebranch block?Bundlebranch block?• Bifascicular block?Bifascicular block?• Identify chamber enlargement.Identify chamber enlargement.• Consider T-wave morphologyConsider T-wave morphology• Consider possible pathologies that correlate Consider possible pathologies that correlate

with altered morphologies.with altered morphologies.

The 6-Step MethodThe 6-Step Method

STE-MimicsSTE-Mimics

• Determine if a paced rhythm, LBBB, LVH, Determine if a paced rhythm, LBBB, LVH, Early repol, pericarditis, WPW, or Early repol, pericarditis, WPW, or hyperkalemia is present.hyperkalemia is present.

• By this step, many possible pathologies have By this step, many possible pathologies have already been ruled out or in.already been ruled out or in.

The 6-Step MethodThe 6-Step Method

Ischemia, Injury, & InfarctIschemia, Injury, & Infarct

• Is it an obvious STEMI? ie. Tombstones?Is it an obvious STEMI? ie. Tombstones?• Identify ST-elevation, & ST-depression.Identify ST-elevation, & ST-depression.• Identify hyperacute T-waves or Q-waves.Identify hyperacute T-waves or Q-waves.• Consider reciprocal changes.Consider reciprocal changes.• Do you show changes in contiguous leads?Do you show changes in contiguous leads?• Consider culprit artery, and affected area of the heart.Consider culprit artery, and affected area of the heart.

12-Lead Basics

The End

• See you in the next module!