12 Lead (Introduction) Rev A

PresentationPresentation

This presentation will briefly cover ECG This presentation will briefly cover ECG

basics. basics.

It has been created with the assumption It has been created with the assumption that the reader will have a solid basic that the reader will have a solid basic knowledge of ECG interpretation.knowledge of ECG interpretation.

If you are not comfortable with interpreting If you are not comfortable with interpreting standard three lead ECGs, it is standard three lead ECGs, it is recommended that you review that recommended that you review that material before moving on to 12 lead ECG.material before moving on to 12 lead ECG.

Program OutlineProgram Outline Brief review of cardiac conduction systemBrief review of cardiac conduction system

The basic beatThe basic beat BioelectricityBioelectricity

Action PotentialsAction Potentials Review of four lead placementReview of four lead placement

Limb leads and augmented leadsLimb leads and augmented leads Hexaxial systemHexaxial system

Precordial lead placementPrecordial lead placement Precordial lead localizationPrecordial lead localization Reflecting leadsReflecting leads Reciprocal leadsReciprocal leads Injury & InfarctInjury & Infarct The “12 lead” ECGThe “12 lead” ECG

J pointJ point Right Ventricular InfarctRight Ventricular Infarct Posterior Wall InfarctPosterior Wall Infarct PericarditisPericarditis

Cardiac Conduction SystemCardiac Conduction System

Conduction Anatomy &Conduction Anatomy & Intrinsic RatesIntrinsic Rates

SA nodeSA node 60-100 60-100 BPMBPM

AV nodeAV node 45-50 BPM45-50 BPM

Ventricles Ventricles 30-40 BPM30-40 BPM

The Basic BeatThe Basic Beat

T-P segment: otherwise known as the Isoelectric line

P wave: Upright, rounded and normally present prior to every QRS complex.

P-R interval: <0.20s

QRS Complex: < 0.12s (or <0.10s depending on text book reference)

J-point: location where the ST segment and QRS complex meet.This is the location that will provide the ST elevation / depression criteria.

ST segment: Normally at the same level as the TP segment and PR interval.

T wave: Normally upright and rounded, should be asymmetrical.

J-point

IonsIons

Ions are positively or negatively charged Ions are positively or negatively charged molecules.molecules.

The main positively charged ion in the The main positively charged ion in the body is sodium (Na+).body is sodium (Na+).

The main negatively charged ion in the The main negatively charged ion in the body is chloride (Cl-). body is chloride (Cl-).

Other common ions in the body include:Other common ions in the body include: Potassium (K+)Potassium (K+) Calcium (Ca++)Calcium (Ca++)

BioelectricityBioelectricity

Bioelectricity is created by the movement of Bioelectricity is created by the movement of ions through a semi-permeable membrane.ions through a semi-permeable membrane.

The main extracellular ion is sodium (Na+).The main extracellular ion is sodium (Na+).

The main intracellular ion is Potassium (K+).The main intracellular ion is Potassium (K+).

Movement of sodium and potassium through Movement of sodium and potassium through the cellular membrane generates electricity.the cellular membrane generates electricity.

ACTION POTENTIALSACTION POTENTIALS

Action PotentialAction PotentialPhase 4:Phase 4:

The semi permeable cell membrane has sodium (Na+) leeching in and Potassium (K+) leaking out.

The Sodium / Potassium pumps work to push out two Sodium ions and bring in one Potassium ion.

At this point the cell is considered net negative. The number of positively charged ions outside the cell membrane is larger than the positive ions inside the membrane.

As time passes the Sodium leeching in to the cell offsets the Na+ / K+ pump and the cell becomes more positively charged.


The increasing Na+ entering the cell has caused the cell to become more positively charged. This is the Threshold Potential, which causes the “fast” sodium channels to open.

This is a one way valve. Since the most abundant extracellular ion is Na+ there is a rush of positive ions into the cell creating a more positive charge.

This continues until the cell is no longer polarized. The net charge is isoelectric on both sides of the cell membrane.

Action PotentialAction PotentialPhase 1: Phase 1:

This phase is when the cell is at This phase is when the cell is at its peak positive charge.its peak positive charge.

At this point negatively charged At this point negatively charged Chloride (Cl-) ions enter the cell Chloride (Cl-) ions enter the cell and cause the fast acting Na+ and cause the fast acting Na+ channels to close.channels to close.


Two different channels open up at Two different channels open up at this point, the “slow” Sodium this point, the “slow” Sodium channels and the Calcium (Ca++) channels and the Calcium (Ca++) channels. channels.

This plateau segment begins. This plateau segment begins.

Calcium is a double positive ion.Calcium is a double positive ion.

CA++ influx with the slowed influx CA++ influx with the slowed influx of Sodium allow the cell to stay in of Sodium allow the cell to stay in a depolarized state for a longer a depolarized state for a longer period.period.

Calcium is crucial for cardiac Calcium is crucial for cardiac muscle contraction, being the key muscle contraction, being the key for Actin / Myosin activation.for Actin / Myosin activation.

Action PotentialAction PotentialPhase 3: Phase 3:

Potassium channels now open Potassium channels now open and allow K+ to leave the cell.and allow K+ to leave the cell.

This exiting of positively charged This exiting of positively charged ions now returns the inside of the ions now returns the inside of the cell to a net negative and the cell cell to a net negative and the cell is repolarized, allowing the whole is repolarized, allowing the whole process to begin again.process to begin again.

Action PotentialsAction Potentials

One thing to remember:One thing to remember: Action Potentials in different myocytes Action Potentials in different myocytes

reach their threshold at different rates.reach their threshold at different rates.

Why is this?Why is this?

Action PotentialsAction Potentials This is part of a protective mechanism.This is part of a protective mechanism.

The SA node reaches action potential The SA node reaches action potential at the fastest rate. This will depolarize at the fastest rate. This will depolarize the other pacemaker sites as electrical the other pacemaker sites as electrical depolarization travels down the heart.depolarization travels down the heart.

If the SA node does not send the If the SA node does not send the impulse then the AV node is the next impulse then the AV node is the next pacemaker to fire, then the pacemaker to fire, then the ventricles……ventricles……

Pacemaker SitesPacemaker Sites

““LIMB” LEAD PLACEMENTLIMB” LEAD PLACEMENT

Four Lead placements, a Four Lead placements, a reviewreview

Starting with the R.A. Starting with the R.A. and L.A. leads being and L.A. leads being placed on the lateral to placed on the lateral to anterior aspects of the anterior aspects of the shoulders. shoulders.

The R.L. and L.L. leads The R.L. and L.L. leads being placed on, or being placed on, or below the waist in the below the waist in the pelvic area. More pelvic area. More commonly on the commonly on the anterior distal tibia.anterior distal tibia.

The only critical criteria The only critical criteria for these leads is that for these leads is that they be a minimum of they be a minimum of 10 cm from the heart. 10 cm from the heart.

Limb Leads and Augmented Limb Leads and Augmented LeadsLeads The Limb electrodes (RA, LA, RL, LL) give us six The Limb electrodes (RA, LA, RL, LL) give us six

actual leads. actual leads.

These are part of the HEXAXIAL system.These are part of the HEXAXIAL system. Hexaxial degrees used in axis calculations, not covered Hexaxial degrees used in axis calculations, not covered

in this presentation.in this presentation.

Leads:Leads: I / II / III / aVR / aVL / aVFI / II / III / aVR / aVL / aVF

Leads are named where the view is from the positive Leads are named where the view is from the positive electrode placement.electrode placement.

The ECG monitor will automatically adjust the polarity of The ECG monitor will automatically adjust the polarity of the leads for different lead view. the leads for different lead view.

These leads look at the heart in two dimensionally (coronal These leads look at the heart in two dimensionally (coronal cut) as if under a plate of glass. cut) as if under a plate of glass.

Hexaxial SystemHexaxial System

PRECORDIALPRECORDIAL LEAD PLACEMENTLEAD PLACEMENT

Precordial LeadsPrecordial Leads

These leads These leads MUSTMUST be placed be placed accurately.accurately.

The placement of precordial leads is The placement of precordial leads is completed as follows. completed as follows.

Precordial Lead placementsPrecordial Lead placements Locate the fourth intercostal space. This is Locate the fourth intercostal space. This is

done by identifying the “Angle of Louis” done by identifying the “Angle of Louis” the small ridge on the top third of the the small ridge on the top third of the sternum, slightly inferior to the sternal sternum, slightly inferior to the sternal notch. This is the location of the second notch. This is the location of the second rib / second intercostal space.rib / second intercostal space.

Locate the second intercostal space and Locate the second intercostal space and count down to the fourth intercostal space. count down to the fourth intercostal space.

On the right lateral aspect of the sternum On the right lateral aspect of the sternum place lead Vplace lead V1 1 on the left lateral aspect of on the left lateral aspect of the sternum place lead Vthe sternum place lead V22. .

Precordial VPrecordial V11 – V – V22

Precordial Lead placementsPrecordial Lead placements

Next slide your Next slide your finger down to finger down to the fifth the fifth intercostal space intercostal space at the left at the left midclavicular midclavicular line. line.

This is where you This is where you will place Vwill place V44. .


Equidistant Equidistant between Vbetween V22 and Vand V44 is the is the landmark landmark placement placement for Vfor V33


Locate the left Locate the left midaxillary midaxillary line at the fifth line at the fifth intercostal intercostal space.space.

This is the This is the placement placement point for Vpoint for V6.6.


VV55 is placed is placed at the fifth at the fifth intercostal intercostal space space between Vbetween V44 and Vand V66 at the at the anterior anterior axillary lineaxillary line

Precordial Lead ViewsPrecordial Lead Views

Limb leads, Augmented leads Limb leads, Augmented leads & & Precordial leads.Precordial leads.

Now that the Now that the precordial leads are precordial leads are in place, we have a in place, we have a three dimensional three dimensional look at the majority look at the majority of the cardiac of the cardiac conduction system.conduction system.

With our leads in place, we With our leads in place, we can now obtain a 12 lead can now obtain a 12 lead

ECGECG.

12 lead ECG12 lead ECG With the 12 lead ECG, practitioners With the 12 lead ECG, practitioners

have the ability to obtain more have the ability to obtain more detailed information in regards to detailed information in regards to cardiac conduction and function. A cardiac conduction and function. A few of these are……few of these are…… Electrical Axis & Axis deviationElectrical Axis & Axis deviation Cardiac HypertrophyCardiac Hypertrophy Ischemia & InjuryIschemia & Injury InfarctionInfarction PericarditisPericarditis Drug toxicityDrug toxicity

12 Lead ECG12 Lead ECG

For this presentation we will focusing For this presentation we will focusing on:on:Location of Injury and InfarctLocation of Injury and Infarct

Including RV + PosteriorIncluding RV + PosteriorFindings for Pericarditis.Findings for Pericarditis.


Contiguous LeadsContiguous Leads

When looking at a 12 lead ECG there are When looking at a 12 lead ECG there are “contiguous” leads. Different leads that look at “contiguous” leads. Different leads that look at the same aspect of the heart.the same aspect of the heart.

Reflecting leads,Reflecting leads, where we are lookingwhere we are looking

Lead ILead I

LateralLateralaVRaVR V1V1

SeptalSeptalV4V4

AnteriorAnterior

Lead IILead II

InferiorInferioraVLaVL

LateralLateralV2V2

SeptalSeptalV5V5

LateralLateral

Lead IIILead III

InferiorInferioraFVaFV

InferiorInferiorV3V3

AnteriorAnteriorV6V6

LateralLateral

Colors reflect contiguous leads.


Reciprocal LeadsReciprocal Leads

These “reciprocal” leads are the These “reciprocal” leads are the electrical opposite of the leads you are electrical opposite of the leads you are viewing.viewing.

Inferior ST depression in II, III, aVF Inferior ST depression in II, III, aVF reciprocal leads (I, aVL V1 – V5) should reciprocal leads (I, aVL V1 – V5) should show ST elevation.show ST elevation.

Reciprocal LeadsReciprocal Leads

Reciprocal LeadsReciprocal LeadsM. I. M. I.

LocationLocationReflecting Reflecting

LeadsLeadsReciprocal Reciprocal

LeadsLeadsBlood Blood SupplySupply

InferiorInferior II, III, aVFII, III, aVF I, aVL, V1-I, aVL, V1-V5V5

RCARCA

SeptalSeptal V1, V2V1, V2 II, III, aVFII, III, aVF LCALCA

AnteriorAnterior V3, V4V3, V4 II, III, aVFII, III, aVF LADLAD

LateralLateral I, V5, V6, I, V5, V6, aVLaVL

II, III, aVFII, III, aVF CircumflCircumflexex

PosteriorPosterior V8, V9V8, V9 V1, V2 large V1, V2 large R waves R waves with ST with ST depressiondepression

Posterior Posterior MarginalMarginal

Reflecting and Reciprocal Reflecting and Reciprocal

Note ST elevation in II, III & aVF. There is ST depression in reciprocal leads I, aVL. We do not see Reciprocal depression in V5, V6 leads as this ECG is a high inferolateral and has RV involvement (more on RV later).


Looking again a the lead diagram we can see the views of the heart based on the precordial and Hexaxial system.

12 lead ECG12 lead ECGIschemia, Injury & InfarctIschemia, Injury & Infarct

In 12 lead ECG interpretation, relative to In 12 lead ECG interpretation, relative to Infarct or Ischemia we are hunting for:Infarct or Ischemia we are hunting for: ST elevation myocardial infarctions (STEMI).ST elevation myocardial infarctions (STEMI). Non ST elevation MI (NSTEMI).Non ST elevation MI (NSTEMI). Ischemia (ST depression).Ischemia (ST depression). Pathologic Q waves Pathologic Q waves

Q waves > than ¼ height of R wave Q waves > than ¼ height of R wave Q waves > 0.04s in durationQ waves > 0.04s in duration

Non Q wave AMINon Q wave AMI

J point, ST segment & T wavesJ point, ST segment & T waves

To be able to find ST abnormalities it To be able to find ST abnormalities it is crucial to be able to identify:is crucial to be able to identify:

J-point: the point where the QRS and ST J-point: the point where the QRS and ST segment join.segment join.

ST segment: normal or abnormal….ST segment: normal or abnormal….

T wave: normal or pathologic…T wave: normal or pathologic…

ST segment & T wavesST segment & T waves The ST segment represents the time The ST segment represents the time

between ventricular depolarization between ventricular depolarization and repolarization.and repolarization.

Together the ST segment and the T Together the ST segment and the T wave are the area that best reflects wave are the area that best reflects Infarct and Ischemic insult to the Infarct and Ischemic insult to the Myocardium.Myocardium.

ST changes are measured from the ST changes are measured from the ““J-point”.J-point”.

J PointJ Point

The J point is the point 1mm behind The J point is the point 1mm behind where the QRS joins the ST Segment.where the QRS joins the ST Segment.

This point can be sharp (easy to This point can be sharp (easy to define) or slurred (more difficult to define) or slurred (more difficult to identify).identify).

Locating the J PointLocating the J Point Where is the J-Point in this ECG?Where is the J-Point in this ECG?

Locating the J PointLocating the J Point Use the isoelectric line or the TP segment as a baselineUse the isoelectric line or the TP segment as a baseline

Locating the J PointLocating the J Point After identifying the baseline, extrapolate where the ST After identifying the baseline, extrapolate where the ST

segment would have returned to the isoelectric line.segment would have returned to the isoelectric line.

Locating the J PointLocating the J Point This is the J – PointThis is the J – Point

Locating the J PointLocating the J Point There is ST elevation in this ECG, about 1 – 2 mm. There is ST elevation in this ECG, about 1 – 2 mm.

Locating the J - PointLocating the J - Point

Where is the J – point in this ECG?Where is the J – point in this ECG?

ST SegmentST Segment The main thing to note in looking at The main thing to note in looking at

the ST segment is its relation to the the ST segment is its relation to the baseline.baseline.

In correlation with the baseline and J In correlation with the baseline and J point we will be better able to identify point we will be better able to identify ST elevation or depression.ST elevation or depression.

Aside from depression and elevation Aside from depression and elevation there are some ST segment shapes we there are some ST segment shapes we need to be familiar with.need to be familiar with.

ST segment shapesST segment shapes

T wavesT waves In speaking to T waves in ischemia In speaking to T waves in ischemia

and infarct what we are looking for and infarct what we are looking for are “pathologic” T waves.are “pathologic” T waves.

Normal T waves are Asymmetrical. Normal T waves are Asymmetrical.

T WavesT Waves Symmetrical T waves are found in Symmetrical T waves are found in

pathologic states, including:pathologic states, including: Ischemia Ischemia Electrolyte Abnormalities Electrolyte Abnormalities CNS issuesCNS issues

However, these symmetrical T waves However, these symmetrical T waves may be a normal electrical variant may be a normal electrical variant within a small segment of the within a small segment of the population.population.

T wavesT waves

T WavesT Waves

Symmetrical T waves should be Symmetrical T waves should be considered pathological until ruled out. considered pathological until ruled out.

Always consider patient presentation. Always consider patient presentation.

ST Depression & ElevationST Depression & Elevation

When evaluating the ST segment and T When evaluating the ST segment and T wave we are looking for Elevation or wave we are looking for Elevation or Depression.Depression.

We are also looking for a regional We are also looking for a regional distribution (contiguous leads) distribution (contiguous leads) Inferior, anterior, septal…etc.Inferior, anterior, septal…etc.

The Following slides will show examples, The Following slides will show examples, which are pathological ST changes and which are pathological ST changes and which are normal variants….which are normal variants….

Progression of Ischemia, Injury Progression of Ischemia, Injury & Infarct& Infarct

ST changes, Good or Bad?ST changes, Good or Bad?

While this is not “normal” this is a tracing of LV strain. Note that the T waves are asymmetrical. While the T’s are inverted there is no real ST depression.

This tracing is indicative of an inferior MI. Note the ST elevation in II / III / aVF with reciprocal depression in I / aVL. Also, in III this may be considered a “pathological” Q wave

ST changes, what do we note?ST changes, what do we note?

As these progress through the transition zone note the notching and slurred j point, as well as high, peaked T’s. This may be a Minimal pericarditis or early repolarization.

Note the ST depression in V1- V3 with reciprocal changes in II, V4 V5 & V6. this may be an inferolateral infarct with some posterior involvement.

ST changes, what do we note?ST changes, what do we note?

This is another example of LV strain. There is a bit of ST elevation in V1-V2. Note however that the T waves are still asymmetrical.

This ECG is showing marked ST depression in V1 – V6 as well as II. This, with the elevation in V1 may be an indicator of diffuse subendocardial ischemia, injury or infarction.

ST ChangesST Changes

This is an example of a left bundle branch block. Wide QRS, Monomorphic S in V1 Monomorphic R in V6. Diagnosing ST in LBB is problematic.

Note the diffuse ST elevation and flipped T’s in V1- V5. This tracing is indicative of an anteroseptal MI with lateral involvement.

Right Ventricular (RV) Right Ventricular (RV) InvolvementInvolvement

Right Ventricular Right Ventricular InvolvementInvolvement

Right Ventricular Involvement can Right Ventricular Involvement can certainly complicate STEMI or AMI certainly complicate STEMI or AMI treatment…….this presentation will treatment…….this presentation will not cover the specific treatment not cover the specific treatment modalities, only recognition of the RV modalities, only recognition of the RV Involvement.Involvement.

Please follow local guidelines or Please follow local guidelines or protocols for all Patient care.protocols for all Patient care.

Right Ventricular and Posterior Right Ventricular and Posterior WallWall

Lead placements Lead placements When placing Right sided leads or posterior When placing Right sided leads or posterior

leads, please follow manufacturer leads, please follow manufacturer instructions, guidelines or your local instructions, guidelines or your local institutional practices.institutional practices.

Certain machines have all the leads available, Certain machines have all the leads available, others require alternate placements of others require alternate placements of standard leads and documentation on the standard leads and documentation on the tracing of lead changestracing of lead changes

RV InvolvementRV Involvement

Lets look at right sided electrode Lets look at right sided electrode placement!!.placement!!.

V4R, V5R, V6R….same criteria for V4R, V5R, V6R….same criteria for placing V4, V5, V6 only on the right placing V4, V5, V6 only on the right side instead of the left side.side instead of the left side.

RV Lead PlacementRV Lead Placement


Can you see the RV criteria? Other than the obvious V4R lead…….lets break it down.


There are several criteria for There are several criteria for identification of RV involvement, lets identification of RV involvement, lets cover these, remembering that not cover these, remembering that not all of these are a requirement for RV all of these are a requirement for RV involvement. involvement.

We will rarely see all of these in a We will rarely see all of these in a tracing, only a couple will usually be tracing, only a couple will usually be identifiable. identifiable.

RV Involvement CriteriaRV Involvement Criteria1.1. Inferior Wall MIInferior Wall MI

2.2. ST Elevation greater in lead III than ST Elevation greater in lead III than IIII

3.3. ST elevation in V1 ST elevation in V1 (with possible extension to V5 – V6)(with possible extension to V5 – V6)

4.4. ST depression in V2 ST depression in V2 (unless elevation extends as in #3)(unless elevation extends as in #3)

5.5. ST depression in V2 can not be more ST depression in V2 can not be more than half the ST elevation in aVFthan half the ST elevation in aVF

6.6. More than one mm elevation in More than one mm elevation in Right sided leads (V4R – V6R)Right sided leads (V4R – V6R)


1.1. IWMI: Inferior wall MIIWMI: Inferior wall MI Approximately 97% of RVI occur with Approximately 97% of RVI occur with

IWMI due to the involvement of the IWMI due to the involvement of the Right Coronary Artery. Whenever you Right Coronary Artery. Whenever you see an inferior MI, check for RVI.see an inferior MI, check for RVI.

These can also occur from a blockage These can also occur from a blockage in the circumflex, but this is rare at in the circumflex, but this is rare at approximately 3% approximately 3%


2.2. ST elevation greater in III than IIST elevation greater in III than II This energy (vector) is directed This energy (vector) is directed

anteriorly and inferior to the right, and anteriorly and inferior to the right, and lead III is directly in its path.lead III is directly in its path.

As this is lead is closer to the vector it As this is lead is closer to the vector it shows a higher ST elevation.shows a higher ST elevation.

The infarct here allows for the energy to The infarct here allows for the energy to travel unopposed through the travel unopposed through the interventricular septum.interventricular septum.

RV InvolvementRV Involvement3.3. ST elevation in V1ST elevation in V1

The ST segment will be elevated in V1, The ST segment will be elevated in V1, this is as mention previously as the this is as mention previously as the energy is travelling unopposed through energy is travelling unopposed through the interventricular septum.the interventricular septum.

This will most often elevate V1 and This will most often elevate V1 and depress V2 as it passes these lead areas.depress V2 as it passes these lead areas.

Remember, although uncommon that Remember, although uncommon that this can cause elevation through V5 – V6.this can cause elevation through V5 – V6.

If you see ST elevation in II / III / aVF and If you see ST elevation in II / III / aVF and V1 this is most likely an MI with RVI.V1 this is most likely an MI with RVI.


4.4. ST depression in V2 ST depression in V2 (Unless elevation as in (Unless elevation as in #3)#3)

This is due to the vector (energy) This is due to the vector (energy) passing away from V2. passing away from V2.

As previously mentioned, the energy is As previously mentioned, the energy is directed more closely to V1, and away directed more closely to V1, and away from V2, therefore creating ST from V2, therefore creating ST depression.depression.

RV InvolvementRV Involvement5.5. ST depression in V2 can not be more ST depression in V2 can not be more

than half the elevation is aVFthan half the elevation is aVF This one is a critical criteria as it points This one is a critical criteria as it points

to either a “simple” RVI or a massive to either a “simple” RVI or a massive amount of myocardium at risk.amount of myocardium at risk.

If the depression is more than half the If the depression is more than half the height of the elevation in aVF then this height of the elevation in aVF then this points to a possible Inferior-posterior-points to a possible Inferior-posterior-RV infarct. This is a massive amount of RV infarct. This is a massive amount of at risk myocaridum.at risk myocaridum.


6.6. More than one mm of elevation in More than one mm of elevation in right sided leads (V4R – V6R)right sided leads (V4R – V6R)

Well, since these are directly looking at Well, since these are directly looking at the RV it is the most specific sign of an the RV it is the most specific sign of an RVI.RVI.

Most cases will show ST elevation in Most cases will show ST elevation in V4R, but some only show in V6R. V4R, but some only show in V6R.

Make it a habit to collect all three Right Make it a habit to collect all three Right sided leads.sided leads.


Rarely do we have isolated RV infarcts, so many of these will have other MI areas associated. What do you note?

Here we see ST elevation in II / III / aFV with lateral reciprocation making this an inferior AMI. What do you see for RV involvement if any?

15-25

RV InvolvementRV Involvement Along with the IWMI, RV involvement Along with the IWMI, RV involvement

criteria here arecriteria here are ST elevation in III greater than IIST elevation in III greater than II ST elevation in V1ST elevation in V1 Elevation greater than 1mm in V4R.Elevation greater than 1mm in V4R.

Three RV criteria, well defined RVIThree RV criteria, well defined RVI


ST elevation in II less than IIIST elevation in II less than III

Elevation in V1Elevation in V1

> 1mm elevation in V4R> 1mm elevation in V4R


What do we see in this 12 lead?

15-26


In the tracing, we see Inferior ST In the tracing, we see Inferior ST elevation and lateral depression elevation and lateral depression making this an IWMI.making this an IWMI.

Looking at our RV Criteria we noteLooking at our RV Criteria we note Elevation in III > II Elevation in III > II Elevation in V1, slight depression in V2Elevation in V1, slight depression in V2 Elevation in V4RElevation in V4R V2 depression < half height of aVF V2 depression < half height of aVF


ST elevation in II less than III

Elevation in V1

ST depression in V2 < half of elevation in aVF

> 1mm elevation in V4R


What do we see in this 12 Lead

15-27


In this 12 Lead we note ST elevation In this 12 Lead we note ST elevation in III / aVF with reciprocal depression in III / aVF with reciprocal depression in I / aVLin I / aVL

Looking at RV criteria we seeLooking at RV criteria we see ST elevation > in III than IIST elevation > in III than II Elevation in V1Elevation in V1 Elevation in V4RElevation in V4R


ST elevation in II less than III

Elevation in V1

> 1mm elevation in V4R

RV InvolvementRV InvolvementWhy is it critical to diagnose the RVI?Why is it critical to diagnose the RVI?

How does the RV fill?How does the RV fill? Mainly through passive venous pressure.Mainly through passive venous pressure.

How does blood get into the lungs? How does blood get into the lungs? Through RV pumping pressure. Through RV pumping pressure.

Where does the oxygenated blood travel?Where does the oxygenated blood travel? To the LV for delivery to the body.To the LV for delivery to the body.

RV InvolvementRV Involvement Most AMI treatments affect preload, and the RV Most AMI treatments affect preload, and the RV

is filled mainly through venous pressure, is filled mainly through venous pressure, passive filling. passive filling.

If we drop preload with standard treatments If we drop preload with standard treatments

(nitrates, beta blockers) we effectively drop BP (nitrates, beta blockers) we effectively drop BP through increasing venous system capacitance through increasing venous system capacitance (venodilation) and cause a decrease in RV (venodilation) and cause a decrease in RV filling.filling.

In-turn, this decreases flow to the lungs for In-turn, this decreases flow to the lungs for exchange, then decreased return to the LV, exchange, then decreased return to the LV, most likely causing a sub-optimal outcome.most likely causing a sub-optimal outcome.

Posterior Wall MIPosterior Wall MI

Posterior MIPosterior MI A posterior wall myocardial infarction A posterior wall myocardial infarction

(PWMI) is not directly visualized on the (PWMI) is not directly visualized on the standard 12 lead.standard 12 lead.

We can see posterior MI through reciprocal We can see posterior MI through reciprocal leads, but require additional leads to view leads, but require additional leads to view the posterior wall.the posterior wall.

V6, V7, V8, V9, V10V6, V7, V8, V9, V10 Most often you will see V8, V9 placedMost often you will see V8, V9 placed

Posterior MIPosterior MI


PWMI, as mentioned are initially observed PWMI, as mentioned are initially observed on a standard 12 lead through reciprocal on a standard 12 lead through reciprocal leads.leads.

These are leads V1, V2These are leads V1, V2


What we see on this ECG is V1, V2 What we see on this ECG is V1, V2 flattened ST depression, this should flattened ST depression, this should prompt you to place the Posterior leads.prompt you to place the Posterior leads.


Again, we see ST depression in V1, V2 which should prompt Posterior lead placement.

PWMI are not usually isolated events and often occur with IWMI and RVI. This is due to these areas being commonly perfused by the same arteries.

•RCA, Posterior Descending, or the LCX

PericarditisPericarditis

ST Changes (Pericarditis)ST Changes (Pericarditis) Full Criteria for Pericarditis in ECG:Full Criteria for Pericarditis in ECG:

PR depressionPR depression Diffuse ST elevationDiffuse ST elevation Scooping, upwardly concave ST Scooping, upwardly concave ST

segmentssegments Notching at the end of the QRSNotching at the end of the QRS

ST Changes (Pericarditis)ST Changes (Pericarditis)

ST elevation can be as high as 4mm ST elevation can be as high as 4mm to 5mm.to 5mm.

ST segment elevation is diffuse, not ST segment elevation is diffuse, not localized to contiguous leads as in localized to contiguous leads as in AMI. Why is this?AMI. Why is this? The entire pericardium is irritated, this The entire pericardium is irritated, this

irritation causes a net positivity of the irritation causes a net positivity of the epicardium.epicardium.

This is electrically displayed as diffuse This is electrically displayed as diffuse ST elevation.ST elevation.



Note the PR depression in II, III as well as ST elevation in II / III / aVF / V2 –V6. The ST elevation is diffuse and not limited to contiguous leads. Also, note there is no reciprocal depression as with AMI. Lastly, there is notching post QRS in V4 – V5.


The PR depression in this example is not very deep, but note the The PR depression in this example is not very deep, but note the marked ST elevation in I, II, aVF and all precordial leads. Vmarked ST elevation in I, II, aVF and all precordial leads. V33 has a has a great look at notching after the QRS complex. great look at notching after the QRS complex.


During care of the patient, you may During care of the patient, you may note the amplitude of the ECG note the amplitude of the ECG diminishing.diminishing.

Fluid build up in the pericardial sac Fluid build up in the pericardial sac may cause amplitude drops.may cause amplitude drops.

Now that we have covered the basics Now that we have covered the basics of 12 lead ECG in consideration of ACS of 12 lead ECG in consideration of ACS and pericarditis, interpret the following and pericarditis, interpret the following ECGs.ECGs.

Practice Interpretation 1Practice Interpretation 1

Anteroseptal AMIAnteroseptal AMI


Inferolateral MI Inferolateral MI (with some RV criteria)(with some RV criteria)


Lateral MILateral MI


Anteroseptal MIAnteroseptal MI


Inferior, Posterior and RV involvementInferior, Posterior and RV involvement


Anteroseptal MIAnteroseptal MI


Inferior – lateral – posterior Inferior – lateral – posterior MI MI


Inferoposterior with RV involvementInferoposterior with RV involvement


PericarditisPericarditis


Inferolateral MI with RV involvementInferolateral MI with RV involvement

12 lead ECG12 lead ECG 12 lead ECG’s are an important diagnostic tool. 12 lead ECG’s are an important diagnostic tool.

Remember that this is only a tool to assist your Remember that this is only a tool to assist your clinical assessment. clinical assessment.

Provide treatment as per local protocols and Provide treatment as per local protocols and with sound medical judgement.with sound medical judgement.

Questions, Comments or Concerns? Questions, Comments or Concerns?

Please contact me at [email protected] contact me at [email protected]

12 lead ECG’s provided by Jones and 12 lead ECG’s provided by Jones and Barlett publishing Barlett publishing 12 lead ECG, the art of interpretation 12 lead ECG, the art of interpretation

Instructor tool kit.Instructor tool kit.

http://www.jblearning.com/catalog/9780763712846/

12 Lead (Introduction) Rev A

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