12 lead-lesson 4

12-Lead 12-Lead ElectrocardiographyElectrocardiography

a comprehensive course

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

Lesson

4

ResourcesResources

http://www.ekgclub.com/

http://www.ekgclub.com/

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 FourLesson Four

• STE-MimicsSTE-Mimics– Any cause of ST-Elevation or AMI-like Any cause of ST-Elevation or AMI-like

patterns that is not associated with an patterns that is not associated with an actual MI.actual MI.

ObjectivesObjectives

• Learn what the different STE-Mimics are.Learn what the different STE-Mimics are.• Learn how to identify a STE-Mimic.Learn how to identify a STE-Mimic.• Learn how to differentiate between a STE-Learn how to differentiate between a STE-

Mimic and a STEMI Mimic and a STEMI – (ST-Segment Elevation Myocardial Infarction)(ST-Segment Elevation Myocardial Infarction)

ST-ElevationST-Elevation

• The most common cause of ST-The most common cause of ST-elevation is not myocardial infarction. elevation is not myocardial infarction.

• Less than 50% of STEMI alerts called Less than 50% of STEMI alerts called by paramedics are actually ACS by paramedics are actually ACS patientspatients


• ST-Elevation is elevation of the J-Point which ST-Elevation is elevation of the J-Point which causes elevation of the following ST-causes elevation of the following ST-Segment.Segment.

• Elevation is defined as anything above the Elevation is defined as anything above the isoelectric line.isoelectric line.

• Find the isoelectric line by locating the TP-Find the isoelectric line by locating the TP-Segment.Segment.

T P

TP-Segment


• The J-Point is where the QRS complex The J-Point is where the QRS complex and the ST-Segment meet.and the ST-Segment meet.J-Point

NERD ALERT!NERD ALERT!

The ResearchThe Research

• Electrocardiographic ST-segment elevation: correct Electrocardiographic ST-segment elevation: correct identification of acute myocardial infarction (AMI) and identification of acute myocardial infarction (AMI) and non-AMI syndromes by emergency physiciansnon-AMI syndromes by emergency physicians (Acad (Acad Emerg Med 2001; 8(4):349-360)Emerg Med 2001; 8(4):349-360)

• 902 patients were enrolled in the study. Of those, 902 patients were enrolled in the study. Of those, 202 202 patients (22.4%) had ST segment elevationpatients (22.4%) had ST segment elevation on on their initial 12 lead ECG. Of those, their initial 12 lead ECG. Of those, only 31 patients only 31 patients (15%) had a discharge diagnosis of STEMI(15%) had a discharge diagnosis of STEMI. In . In other words, 171 patients (85%) had a non-AMI cause other words, 171 patients (85%) had a non-AMI cause of ST segment elevation on their initial 12 lead ECGof ST segment elevation on their initial 12 lead ECG

Causes of ST-ElevationCauses of ST-Elevation

Listed from most common to least:Listed from most common to least:• Left ventricular hypertrophy (LVH) Left ventricular hypertrophy (LVH) • Left bundle branch block (LBBB)Left bundle branch block (LBBB)• Benign early repolarization (BER) Benign early repolarization (BER) • Right bundle branch block (RBBB)Right bundle branch block (RBBB)• Nonspecific BBBNonspecific BBB• Ventricular AneurysmVentricular Aneurysm• PericarditisPericarditis• Undefined or unknown causeUndefined or unknown cause

Causes of ST-ElevationCauses of ST-Elevation

Easier way to remember:Easier way to remember:E - Electrolytes (hyperkalemia)E - Electrolytes (hyperkalemia)

L - LBBBL - LBBB

E - Early repolarizationE - Early repolarization

V - Ventricular hypertrophy (LVH)V - Ventricular hypertrophy (LVH)

A - AneurysmA - Aneurysm

T - Treatment (e.i. pericardiocentesis)T - Treatment (e.i. pericardiocentesis)

I - Injury (AMI, contusion)I - Injury (AMI, contusion)

O - Osborne waves (hypothermia)O - Osborne waves (hypothermia)

N - Non-occlusive vasospasmN - Non-occlusive vasospasm

More ResearchMore Research

• ““Paramedics diagnosed over half of Paramedics diagnosed over half of patients as having ST elevation patients as having ST elevation AMI, when in fact they did not. One AMI, when in fact they did not. One reason for this may be that the reason for this may be that the paramedics were concerned about paramedics were concerned about missing patients with this missing patients with this condition.”condition.”

Also From The ResearchAlso From The Research

• The incidence of poor quality ECGs recorded The incidence of poor quality ECGs recorded by the paramedics was calculated to by the paramedics was calculated to determine the paramedics performance in determine the paramedics performance in electrocardiographic acquisition. electrocardiographic acquisition.

• In 13 of 124 patients (10.5%), the ECGs In 13 of 124 patients (10.5%), the ECGs were characterized as poor quality...were characterized as poor quality...""

Lead PlacementLead Placement

• Poor ECG captures Poor ECG captures were noted as a were noted as a common problem.common problem.

• V3 is most commonly V3 is most commonly misplaced leadmisplaced lead

Which Electrode is Causing Which Electrode is Causing Artifact?Artifact?

• Precordial leads are easy. V1 has Precordial leads are easy. V1 has artifact? Check V1 electrode.artifact? 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 If Leads I & II have artifact, check right shoulder.right shoulder.

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

What are Contiguous Leads?What are Contiguous Leads?

• Contiguous leads are leads that look at Contiguous leads are leads that look at the same area of the heart. the same area of the heart.

• They show up on the 12-lead proximal They show up on the 12-lead proximal to each other.to each other.

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

Reciprocal ChangesReciprocal Changes

• Reciprocal changes are changes like Reciprocal changes are changes like ST-depression or T-Wave inversion in ST-depression or T-Wave inversion in leads opposite to the site of injury.leads opposite to the site of injury.

Site Facing ReciprocalSeptal V1, V2 V7, V8, V9

Anterior V3, V4 None

Anteroseptal V1, V2, V3, V4 V7, V8, V9

Lateral I, aVL, V5, V6 II, III, aVF

Anterolateral I, aVL, V3, V4, V5, V6 II, III, aVF

Inferior II, III, aVF I, aVL

Posterior V7, V8, V9 V1, V2, V3, V4

Left Ventricular HypertrophyLeft Ventricular Hypertrophy

• The “Strain Pattern” is a The “Strain Pattern” is a repolarization abnormality repolarization abnormality associated with LVH and may associated with LVH and may cause ST-Segment changes.cause ST-Segment changes.

• STEMI is more difficult, but still STEMI is more difficult, but still possible to identify in the presence possible to identify in the presence of LVH.of LVH.

LV StrainLV Strain

• "Strain""Strain" is a pattern of asymmetric ST is a pattern of asymmetric ST segment depression and T wave segment depression and T wave inversion. LV strain is most commonly seen in inversion. LV strain is most commonly seen in one or more leads that look at the left one or more leads that look at the left ventricle (leads I, aVL, V4, V5, V6); less ventricle (leads I, aVL, V4, V5, V6); less commonly it can be seen in inferior leads.commonly it can be seen in inferior leads.

LV Strain PatternLV Strain PatternLeft Precordial Leads Right Precordial LeadsLeft Precordial Leads Right Precordial Leads

V4, V5, V6 V1, V2, V3V4, V5, V6 V1, V2, V3

Normal Complex

LV StrainLV Strain

• 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 Discordance

LVH CluesLVH Clues

• QRS Duration < 120 ms (Not BBB)QRS Duration < 120 ms (Not BBB)• T wave Discordance (widened QRS/T angle)T wave Discordance (widened QRS/T angle)• Concave ST-Segments with asymmetrical T wavesConcave ST-Segments with asymmetrical T waves• The height of STE and T waves are directly proportionate The height of STE and T waves are directly proportionate

to the depth of the S waves.to the depth of the S waves.• The taller the R wave the deeper the ST depression.The taller the R wave the deeper the ST depression.• STE in right precordial leads with depression in left STE in right precordial leads with depression in left

precordial leads due to “strain pattern”. precordial leads due to “strain pattern”.

• Deep narrow dagger-like Q waves have been Deep narrow dagger-like Q waves have been noted in lateral leads with hypertrophic noted in lateral leads with hypertrophic cardiomyopathy.cardiomyopathy.

LV-StrainLV-Strain

LV-Strain

RV-StrainRV-Strain

• Indicates a pathology of the right Indicates a pathology of the right ventricle.ventricle.– R:S ratio > 1 in V1 or V2R:S ratio > 1 in V1 or V2– S1Q3T3 PatternS1Q3T3 Pattern

• S-Wave in Lead I, Q-wave & Inverted T-wave in S-Wave in Lead I, Q-wave & Inverted T-wave in Lead IIILead III

• This indicates acute cor pumonale or This indicates acute cor pumonale or pulmonary embolism.pulmonary embolism.S-Wave Q-Wave

InvertedT-Wave

I III

RV-StrainRV-Strain

• An R:S ratio of > 1 in V1 or V2 An R:S ratio of > 1 in V1 or V2 indicates RVH.indicates RVH.– This means that the R-Wave is This means that the R-Wave is

bigger than the S-Wave in V1 or bigger than the S-Wave in V1 or V2.V2.

• May cause ST-Segment May cause ST-Segment Elevation due to T-Wave Elevation due to T-Wave discordance.discordance.

• P-Pulmonale is also a common P-Pulmonale is also a common finding with RV-Strainfinding with RV-Strain

V1/V2

Left Bundle Branch BlockLeft Bundle Branch Block

• LBBB may also mimic a STEMILBBB may also mimic a STEMI– Delayed conduction due to a block of both the Left Delayed conduction due to a block of both the Left

Anterior Fascicle & Left Posterior Fascicle.Anterior Fascicle & Left Posterior Fascicle.– Atrial rhythm with QRS duration > 120 ms and Atrial rhythm with QRS duration > 120 ms and

negatively deflected QRS complex in V1.negatively deflected QRS complex in V1.– May cause ST-elevation due to T-Wave May cause ST-elevation due to T-Wave

discordance. discordance.

LBBB ResearchLBBB Research

• The evidence shows that there is no correlation between a new LBBB and ACS despite what was previously believed. – Am J Emerg Med 2009;27:916-921.

STE due to LBBBSTE due to LBBB

• Like LVH, STE may be caused by the T wave Like LVH, STE may be caused by the T wave discordance normally found with a LBBB.discordance normally found with a LBBB.

• Acute Myocardial Infarction can still be Acute Myocardial Infarction can still be diagnosed in the presence of LBBB.diagnosed in the presence of LBBB.– This is not a commonly known fact, and many This is not a commonly known fact, and many

texts teach that an AMI can not be identified in the texts teach that an AMI can not be identified in the presence of LBBBpresence of LBBB

T-Wave Discordance

Benign Early Repolarization Benign Early Repolarization (BER)(BER)

• BER may present with an appearance of ST-BER may present with an appearance of ST-elevation. elevation.

• Notched J points are the most commonly taught Notched J points are the most commonly taught indicator of “early repol”.indicator of “early repol”.

• The ST-segment morphology is the easiest way to The ST-segment morphology is the easiest way to determine malignancy of the finding.determine malignancy of the finding.

• LOOK for reciprocal changes!!!LOOK for reciprocal changes!!!

Early RepolarizationEarly Repolarization

• If mean amplitude of R wave in V2-V4 > 5mm If mean amplitude of R wave in V2-V4 > 5mm than BER is more likely.than BER is more likely.

• Consequently if the mean amplitude of V2-V4 Consequently if the mean amplitude of V2-V4 is < 5 mm, the probability the patient is is < 5 mm, the probability the patient is suffering from an MI is almost 99%.suffering from an MI is almost 99%.

• An MI is still possible even if the above An MI is still possible even if the above criteria does not indicate so. criteria does not indicate so.

ST-Segment MorphologyST-Segment Morphology

• Concave ST-Elevation is generally more Concave ST-Elevation is generally more benign.benign.– However, an MI may present with concave However, an MI may present with concave

ST-Elevation.ST-Elevation.

• Convex ST-Elevation is almost always Convex ST-Elevation is almost always an indication of an MI.an indication of an MI.

Concave Convex

J-Point J-Point

Benign Early RepolarizationBenign Early Repolarization

• Notched J-Points are Notched J-Points are sure indicators of sure indicators of benign early benign early repolarizationrepolarization

Right Bundle Branch BlockRight Bundle Branch Block

• A conduction delay due to blockage of A conduction delay due to blockage of the only right fascicle. the only right fascicle.

• ST-segment usually not altered by the ST-segment usually not altered by the normal T wave discordance of RBBB. normal T wave discordance of RBBB.

• QRS duration > 120 ms with positive QRS duration > 120 ms with positive terminal QRS deflection in V1.terminal QRS deflection in V1.


• Identify your J pointIdentify your J point• Compare J point to leads above and below to Compare J point to leads above and below to

make certain you have the correct spot.make certain you have the correct spot.• Identify Isoelectric lineIdentify Isoelectric line• Compare J point to isoelectric line.Compare J point to isoelectric line.• STE > 1mm in limb leads or 2mm in STE > 1mm in limb leads or 2mm in

precordial leads = STEMIprecordial leads = STEMI

Left Ventricular AneurysmLeft Ventricular Aneurysm

• Localized area of infarcted myocardium Localized area of infarcted myocardium that bulges outward during both systole that bulges outward during both systole and diastole.and diastole.

• Due to old infarctionDue to old infarction• May cause varying degrees of persistent May cause varying degrees of persistent

STE < 4mm.STE < 4mm.• No reciprocal changes present.No reciprocal changes present.• Deep Q waves in leads with STE.Deep Q waves in leads with STE.• Most common in V1-V3. Most common in V1-V3.

Acute PericarditisAcute Pericarditis

• Inflammation of the pericardium (pericardial sac).Inflammation of the pericardium (pericardial sac).• May present with global STEMay present with global STE• STE may appear pronounced due to PR-STE may appear pronounced due to PR-

depression. depression. • Tip - STE will be present in leads I & II, even Tip - STE will be present in leads I & II, even

though these leads are reciprocal to each other in though these leads are reciprocal to each other in most patients.most patients.

• aVR will present with ST-depressionaVR will present with ST-depression

QuickTime™ and a decompressor

are needed to see this picture.


• Stage IStage Ieverything is UP everything is UP – ST elevation in almost all leadsST elevation in almost all leads

• Stage IIStage IITransition Transition – "pseudonormalization""pseudonormalization"

• Stage IIIStage IIIEverything is DOWN Everything is DOWN – inverted T wavesinverted T waves

• Stage IVStage IV Normalization. Normalization.


Stage 1 Stage 2 Stage 3Stage 1 Stage 2 Stage 3

HyperkalemiaHyperkalemia

• Peaked, usually narrow, symmetrical T Peaked, usually narrow, symmetrical T waveswaves

• Severe hyperkalemia may present with Severe hyperkalemia may present with straight line from tip of S wave (nadir) to peak straight line from tip of S wave (nadir) to peak of T wave, AKA Sine wave. of T wave, AKA Sine wave.

• Sometimes presents with wide complexes, Sometimes presents with wide complexes, possibly lacking P waves. Z-Fold pattern is possibly lacking P waves. Z-Fold pattern is common with severe hyperkalemia. common with severe hyperkalemia.

• Use medical history to help determine cause.Use medical history to help determine cause.


• 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

Hyperkalemia

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

Osborn Waves

Other STE-MimicsOther STE-Mimics

• Brugada SyndromeBrugada Syndrome - AKA Sudden Unexpected - AKA Sudden Unexpected Death Syndrome. RBBB morphology in V1.Death Syndrome. RBBB morphology in V1.

• Takotsubo CardiomyopathyTakotsubo Cardiomyopathy - non-ischemic - non-ischemic cardiomyopathy in which there is a sudden temporary cardiomyopathy in which there is a sudden temporary weakening of the myocardium. Because this weakening of the myocardium. Because this weakening can be triggered by emotional stress, weakening can be triggered by emotional stress, such as the death of a loved one, the condition is such as the death of a loved one, the condition is also known as also known as broken heart syndromebroken heart syndrome

STE-Mimics

• Take a big look at the entire clinical picture.

• Often, a pathology has not read up on what it is suppose to look like on an ECG, and breaks all the rules.

Lesson 4Lesson 4

• This is the end of Lesson 4This is the end of Lesson 4

• In Lesson 5 we will discuss ischemia, In Lesson 5 we will discuss ischemia, injury, and infarct.injury, and infarct.

12 lead-lesson 4

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Transcript of 12 lead-lesson 4