Demystifying clinical electrocardiography august, 2013

““DEMYSTIFYING CLINICAL DEMYSTIFYING CLINICAL ELECTROCARDIOGRAPHY”ELECTROCARDIOGRAPHY”

… … HHighlighting ighlighting Myocardial Ischemia, Injury & Infarct

©Kristy Molnar, Partner, Critical Care Consultants, 2013©Kristy Molnar, Partner, Critical Care Consultants, 2013

PHILIPS HEALTHCARE

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© Copyright, 2013

Critical Care Consultants

Kristy Molnar

Partner, Nursing Education Consultant

CRITICAL CARE CONSULTANTS

Demystifying Clinical Demystifying Clinical Electrocardiography …Electrocardiography …

Goals of ECG MonitoringGoals of ECG Monitoring

To detect and document cardiac To detect and document cardiac arrhythmiasarrhythmias

To detect and document ST changes and To detect and document ST changes and evolving ischemiaevolving ischemia

To detect prolonged QT interval syndromeTo detect prolonged QT interval syndromeTo evaluate the effectiveness of treatmentTo evaluate the effectiveness of treatment

We’ve come a LONG Way!We’ve come a LONG Way!

http://www.ecglibrary.com/ecghist.html


In order to meet the goals of ECG monitoring, it should ideally be continuous and should reflect a minimum of 12 leads simultaneously.

Ideally 16 leads


Comprehensive arrhythmia diagnosis often requires a MULTI-LEAD perspective,

Ischemia detection can only occur IF the associated leads are viewed,

Transient events of diagnostic/therapeutic importance may not persist LONG ENOUGH to allow documentation with a standand ECG.

Patient Monitoring Survey-Patient Monitoring Survey-THEN vs NOWTHEN vs NOW

Independent survey at AACN’s Advanced Practice Institute Conference (1998)

N=400 (Acute care Nurses and Clinical Specialists)

69% of respondents did not have the clinical capability

31% had the ability to monitor continuous 12-Lead ECG.

Continuous ECG MonitoringContinuous ECG Monitoring

Those using continuous 12-Lead ECG monitoring indicated that their primary reasons are for: – assessment of cardiac condition – changes in condition– differentiation of abnormal or irregular

rhythms.

Continuous ECG MonitoringContinuous ECG Monitoring

The reasons for infrequent use included lack of training, “not a requirement”, and no perceived need.

66% of participants responded that there were barriers to continuous 12-lead monitoring … number of electrodes … lack of training was the primary barrier

The IdealThe IdealMonitoring Situation:Monitoring Situation:

Continuous, real-timeMulti-lead perspectiveSensitive and specificConvenient and stable electrode positionsEasy to landmark (consistent, quick and

reproducible)Patient comfort and low interference with

clinical procedures.

2004 Practice Standards …2004 Practice Standards …

Practice Standards, Practice Standards, the beginningthe beginning

Source: Drew, BJ et al Circulation, 2004 October 26; 110(17):2721-46.

Full text article: www.circ.ahajournals.orgGuidelines: www.guideline.gov

http://www.circ.ahajournals.org/

http://www.guideline.gov/

2009 AHA, ACC, HRS Practice Standards2009 AHA, ACC, HRS Practice Standards

Recommendations for the Standardization and Interpretation of the Electrocardiogram – Part IV (Feb. 19, 2009)

Learning Needs? … Learning Needs? … it appears so!it appears so!

Ongoing Investigations … Ongoing Investigations … 20132013

Review of Electrocardiographic Review of Electrocardiographic PrinciplesPrinciples

Functional Anatomy

& Physiology

Electrical SystemElectrical System

The heart has an intrinsic electrical system that allows for the origination and transmission of an electrical impulse.– The electrical stimulus (initiating

factor)– Depolarization (proliferating

factor)

Cardiac Cell PropertiesCardiac Cell Properties

AutomaticityExcitabilityConductivityContractility

Electrical Conduction SystemElectrical Conduction System

SA Node“Internodal Pathways”AV JunctionBundle of HisBundle BranchesPurkinje Fibres

Sinoatrial (SA) NodeSinoatrial (SA) Node

Right atrium (superior, right orientation)Close to the superior vena cavaSpecialized piece of conduction tissue with

the property of automaticity.60-100 bpm, fastest rate of automaticity

normally, thereby setting the pace of the heart.

The SA Node -The SA Node -Automaticity & ExcitabiltyAutomaticity & Excitabilty

Innervated by the autonomic nervous system. Sympathetic stimulation can accelerate the SA

node up to a rate of 150-160/min. Parasympathetic stimulation can slow the heart

rate to less than 60/min. If the heart was separated from the body’s nervous

system, the SA node could still initiate its own impulses.

ConductivityConductivity

Once an electrical stimulus is originated, it spreads throughout the remainder of the conduction system and the heart muscle.


When the impulse is released from the SA node, it travels throughout the atria, causing them to depolarize and subsequently, contract.

The depolarization wave arrives at the AV node, which is located on the inferior-right side of the intra-atrial septum.


The wave is delayed there for approximately .10 seconds before arriving at the Bundle of His … allowing for atrial contraction to precede ventricular contraction (contributing to adequate ventricular filling, an additional 20-30% of preload).

AV JunctionAV Junction

Under normal conditions, the AV junctional tissue is not the pacemaker of the heart – since it has a lower rate of automaticity than the SA Node.

The rate of impulse formation in the AV junctional tissue is normally 40-60/min.

A-V ConductionA-V Conduction

The cardiac impulse spreads to the thin bundle of “threads” known as the bundle of His

The bundle of His connects the AV junction to the bundle branches (located in the right side of the intra-atrial septum just above the ventricles)

Intraventricular ConductionIntraventricular Conduction

The conduction structures in the ventricles consist of the conduction structures below the bundle of His, also known as the His-Purkinje network.

The impulse passes down the Left and Right bundle branches in a sequential fashion.

Intraventricular ConductionIntraventricular Conduction

Bundle Branch ConductionBundle Branch Conduction

Repolarization is faster in the Left Bundle Branch, therefore it is ready to conduct earlier than the Right Bundle Branch.

Conduction of the impulse is normally Left before Right.

Left vs. Right Bundle BranchLeft vs. Right Bundle Branch

The Right bundle is a slender fascicle that runs along the right side of the intraventicular septum and supplies the electrical impulses to the Right ventricle.

The Left bundle supplies the electrical impulses to the Left ventricle. It runs along the left side of the intraventricular septum and divides almost immediately into an anterior and posterior division (fascicle).

Divisions of the Left BundleDivisions of the Left Bundle

Anterior Fascicle – much longer and thinner of the two and supplies the anterior and superior portions of the Left Ventricle with electrical impulses

Posterior Fascicle – shorter and thicker and supplies the posterior and inferior portions of the Left Ventricle with electrical impulses.

Purkinje Network (Fibers)Purkinje Network (Fibers)

The bundle branches terminate in a network of fibers that are located in both the left and right ventricular walls.

The impulse travels into the Purkinje Fibers and cause ventricular depolarization (and subsequently, contraction)

What is an What is an Electrocardiogram?Electrocardiogram?

Electrocardiogram (ECG)Electrocardiogram (ECG)Depolarization and subsequent

Repolarization spreading throughout the heart can be recorded (on paper or electronically)

Recorded process is called the electrocardiogram.

Changes in cellular polarity (charges) occurring during depolarization and repolarization produces deflections on the recording, forming an “ECG complex”.

ElectrocardiogramElectrocardiogram

““P,Q,R,S,T & U”P,Q,R,S,T & U”

Waves, Complexes, Intervals & Segments

Waves and ComplexesWaves and Complexes

Deviations from isoelectricPositive or Negative?May be Biphasic, Notched or “Flattened”A complex may contain multiple waves

P waveP wave

Atrial depolarizationP wave = Atrial DepolarizationUpright and slightly rounded< 2.5 mm amplitude; 2.5 small squares (.10

sec) duration; not notched or peakedTa wave (Repolarization) normally not seen

– coincides with QRS … opposite polarity to P wave

QRS ComplexQRS Complex

Wave of depolarization reaches the ventricular myocardium via the Purkinje fibres

Ventricular depolarizationRepresented by the “QRS”

complex

Morphology of QRS Morphology of QRS Complexes – “Rules”Complexes – “Rules”

QRS may be composed of a Q wave, R wave and an S wave, or various combinations

Positive versus Negative deflections?R is always positiveQ and S are always negativeQ must precede an RS must follow an R

Morphology of QRS Morphology of QRS Complexes – “Questions”Complexes – “Questions”

R wave?Q wave or a q wave?S wave?QS complex or a pathological Q?RsR1 and other configurations?

Examples of QRS ComplexesExamples of QRS Complexes

Changes in R wave Changes in R wave or a new Q wave?or a new Q wave?

R wave changes can be clinically significant in an acute situation (conduction abnormality or decrease in depolarization forces) … CAUTION – Lead Placement & Filters

What about the development of a new Q wave?

T waveT wave

Ventricular repolarization is represented by the T wave

Normally upright and slightly rounded

Same polarity as mean QRS vector

Should not exceed 1/3-1/4 of the total QRS height

U waveU wave

Sometimes seen after a T waveThought to relate to events of later

repolarization of the ventriclesSame polarity as the T wave

Intervals and SegmentsIntervals and Segments

Intervals contain wavesSegments are between the waves

PR IntervalPR Interval

From the beginning of the P wave to the beginning of the QRS complex.

Represents depolarization of the atria and the spread of the depolarization wave up to and including the Purkinje fibres

His Bundle ElectrocardiogramHis Bundle Electrocardiogram

PR SegmentPR Segment

Represents the period of time between the P wave and the subsequent QRS complex.

This should be isoelectric? PR sagging … atrial

repolarization abnormalities

QRS IntervalQRS Interval

Should be less than .10 sec in duration

Duration of .10 or > should be suspect

R-wave should not be slanted or slurred

No notching of R or S

Intervals and Segments –Intervals and Segments –VATVAT

Ventricular Activation Time (VAT) Beginning of the QRS to the peak of the R wave

(or R1) Time necessary for the depolarization wave to

travel from the endocardium to the epicardium Time longer for LV than RV due to relative

muscle mass Earlier & more sensitive indicator than a global

increase in QRS duration

Ventricular Activation TimeVentricular Activation Time

ST SegmentST Segment

From the end of the QRS complex (at junction point) to the onset of the ascending limb of the T wave

Should be isoelectric … look for depression or elevation

ST SegmentST Segment

Sensitive indicator of myocardial ischemia or injury!!

QT IntervalQT Interval

The time from the beginning of the QRS complex to the end of the T wave

Represents both ventricular depolarization and repolarization

Prolongation increases the risk of significant dysrhythmias

QTc an important calculation and ongoing assessment criteria

QT IntervalQT Interval

QT/QTc Interval MonitoringQT/QTc Interval Monitoring

Who, What, When, Where, Why??

Importance – and challenge – Importance – and challenge – of QT monitoringof QT monitoring

QT prolongation can indicate a risk of severe arrhythmias, torsades de pointes, and sudden cardiac death.

Significance of QTc Significance of QTc MonitoringMonitoring

Importance – and challenge – Importance – and challenge – of QT monitoringof QT monitoring

A growing number of anti-arrhythmic, anti-psychotic, and antibiotic medications can cause QT prolongation

A combination of variables can put your patient at risk.

Increased Risk for Torsades Increased Risk for Torsades de Pointesde Pointes

QT prolonging drugs (this list is LONG)FemalesOlder PatientsBradycardiaImpaired LV function (ischemia, LV

hypertrophy)HypokalemiaHypomagnesemia

QT and QTcQT and QTc

The QT has an inverse relationship to HR.QT = QTc at a HR of 60 bpm onlyHeart rate corrected QT interval is

abbreviated as QTcCorrection formulas, including the Bazett

and Fridericia, are population based & may not be representative for a particular patient

Drugs may also change the relationship between QT and HR

Normal QTc values?Normal QTc values?

Regardless of the 4 correction formulas used, a QTc of < 460 ms in women and < 460 ms in men is considered normal.

Clinical Guidelines suggest that Bazett and Fridericia formulas be included in all drug study submissions. Philips defaults to Bazett, but the configuration supports both.

CompatibilityCompatibility

Continuous QT/QTc measurement is part of the Philips ST/Arrhythmia algorithm

Available on all IntelliVue Patient Monitors, Information Centre and Telemetry Systems.

3-Lead, 5-Lead, 6-Lead, EASI-derived 12-Lead & 12-Lead systems

““Normal” ECG WaveformNormal” ECG Waveform

Understanding Monitoring Understanding Monitoring Principles and ConceptsPrinciples and Concepts

Vectors, Leads, Polarity and Deflections …

How are they all related?

Recording of Electrical Forces Recording of Electrical Forces – The Lead Concept– The Lead Concept

A lead is an electrical system to record electrical activity

Multiple Leads are used in cardiac monitoring and ECG recording systems

A lead is composed on a negative and a positive pole

Sense the direction and magnitude of electrical forces


Record surface information from different regions (or walls) of the myocardium.

The positive pole on any respective lead is the “sensing electrode”

It records electrical activity according to its perspective only (narrow and limited view)


Electrical forces traveling TOWARD a positive pole, will be recorded as a POSITIVE (upright) deflection.

Forces traveling AWAY FROM the leads positive pole (toward it’s negative pole) will be recorded as a NEGATIVE (downwards) deflection.

The Positive Electrode’s ViewThe Positive Electrode’s ViewTOWARD =POSITIVE

DEFLECTION

AWAY = NEGATIVE

DEFLECTION

Planes of the HeartPlanes of the Heart

FrontalHorizontalSagittal

Frontal PlaneFrontal Plane

Superior

Inferior

LeftRight

The 6 Frontal Plane LeadsThe 6 Frontal Plane Leads

Lead ILead IILead IIIaVRaVLaVF

Horizontal PlaneHorizontal Plane

LeftRight AnteriorPosterior

The Horizontal Plane LeadsThe Horizontal Plane Leads

V1 V2 V3 V4 V5 V6

The Horizontal Plane LeadsThe Horizontal Plane Leads

(V7) (V8) (V9) V1R V2R V3R V4R V5R V6R

(Sagittal Plane)(Sagittal Plane)

RightLeft

Posterior

Anterior

Standard 12 LeadStandard 12 Lead

2D - Frontal and Horizontal Plane Views

Bipolar LeadsBipolar Leads

Each lead has two physical poles, a positive pole and a negative pole

Lead I, II and III(also referred to as limb leads or extremity

leads, because of their placement on the body)

Einthoven’s Triangle

Einthoven’s 1st ECG MachineEinthoven’s 1st ECG Machine

1896 1912

Leads I, II and IIIform the equilateral “Einthoven’s Triangle”

Einthoven’s TriangleEinthoven’s Triangle

Placement of Limb LeadsPlacement of Limb Leads

Formation of the Triaxial SystemFormation of the Triaxial System

Unipolar LeadsUnipolar Leads

Many years following Einthoven’s simple invention, the ECG was improved by adding the unipolar leads (Wilson, 1934)

These leads are unipolar since there is only a designated positive electrode

The negative pole is electrically averaged by the ECG machine and the voltage augmented (Goldberger, 1942)

Unipolar LeadsUnipolar Leads

Augmented (by 50%) Voltage … Right, Left, Foot

aVR, aVL, aVF

aVR, aVL, aVFaVR, aVL, aVF

Unipolar Augmented Leads – Frontal Plane

Frontal Plane LeadsFrontal Plane LeadsThe Hexaxial SystemThe Hexaxial System

Horizontal Plane LeadsHorizontal Plane Leads The horizontal plane is traditionally viewed by six

unipolar leads … additional leads are sometimes applied.

Also referred to as “Precordial Leads”, “Chest Leads” or “V Leads”

Positive pole is determined by the physical placement on the chest

The negative pole is electrically averaged (from all three extremity electrodes) and is situated somewhere in the middle of the chest cavity.

Horizontal Plane LeadsHorizontal Plane LeadsThe “V” or Chest LeadsThe “V” or Chest Leads

Anatomical Landmarking of Anatomical Landmarking of Chest LeadsChest Leads

V1 – 4th ICS immediately to the right of the sternum

V2 – 4th ICS immediately to the left of sternum

V3 – Directly between V2 and V4V4 – 5th ICS, left mid-clavicular lineV5 – 5th ICS, left anterior axillary lineV6 – 5th ICS, left mid-axillary line

Cardiac LandmarksCardiac Landmarks

Placement of Chest LeadsPlacement of Chest Leads

2

3

4

5

The Resultant 12 LeadsThe Resultant 12 Leads

Right-sided Chest LeadsRight-sided Chest Leads

V1R– 4th ICS immediately to the left of the sternum

V2R – 4th ICS immediately to the right of sternum

V3R – Directly between V2R and V4R V4R – 5th ICS, right mid-clavicular lineV5R – 5th ICS, right anterior axillary lineV6R – 5th ICS, right mid-axillary line

MIRROR IMAGE OF LEFT-SIDED CHEST LEADS

Right Ventricular LeadsRight Ventricular Leads

Right Ventricular InfarctRight Ventricular Infarct

Posterior Chest LeadsPosterior Chest Leads

V7 – 5th ICS posterior axillary lineV8 – 5th ICS midscapular lineV9 – 5th ICS midspinal line

EXTENSION OF LEADS TO LATERAL-POSTERIOR

12-Lead Electrocardiogram12-Lead Electrocardiogram

Lead Options for Clinical Monitoring and Diagnostic Purposes

Lead Options for Clinical Lead Options for Clinical Monitoring and DiagnosisMonitoring and Diagnosis

CONVENTIONAL: 10 Leads applied with Standard Limb Lead placement

MODIFIED: 10 Leads applied with Modified Limb Lead placement (Mason-Likar, 1966 - for exercise testing)

EASITM Lead Placement: 5 Leads (derived 12-Lead, using vectorcardiography)

Conventional versus Modified Conventional versus Modified Lead Placement for 12 LeadLead Placement for 12 Lead

CONVENTIONAL (Standard): Limb electrode placement on the limbs (forearms and lower legs)

MODIFIED (Mason-Likar): Limb electrode placement on the torso (in same locations, as used for standard continuous ECG monitoring ... BUT!)

Modified lead placement not to be used for Diagnostic ECG Interpretation

EASIEASI® 12 Lead® 12 Lead

Continuous, Real-time & Trending 12-Lead and ST Segment Monitoring


Provides 12-lead data from 5 electrodes, instead of the standard 10 electrode system.

Uses vectorcardiography, with leads placed in a modified X,Y, Z configuration

When compared to conventional 5-Lead ECG monitoring systems, EASI provides more data and has been shown to be superior at detecting myocardial ischemia and cardiac arrhythmias.


Innovative, clinically validated approach to ECG monitoring

Derivation of 12 ECG leads using a 5-electrode configuration

Science behind EASI is based on Dr. Gordon Dower’s adaptation of 3-D vectorcardiography (modified Frank vector leads)


Innovative, clinically validated approach to ECG monitoring

Derivation of 12 ECG leads using a 5-electrode configuration

EASI 12-Lead algorithm derives full 12-lead ECG data to detect and document cardiac arrhythmias and ST changes under continuous monitoring conditions across the care continuum.


3 EASI3 EASI® Vectors® Vectors

E = Lower Sternum (Brown)

A = 5th ICS, Right MAL (Red)

S = Upper Sternum (Black)

I = 5th ICS, Left MAL (White)

Lead ES S (-) to E (+) Lead AS S (-) to A (+) Lead AI I (-) to A (+)

3 EASI3 EASI® Vectors® Vectors

Clinical Advantages of Clinical Advantages of EASIEASI® 12 Lead® 12 Lead

Convenient, stable electrode positions on obvious anatomical landmarks enhancing access, accuracy and reproducibility

Need for fewer electrodes increases patient comfort and mobility

Ease of use results in time savings for care givers


Innovative lead configuration achieves superior signal-to-noise ratios

Left precordium is always free … low interference with clinical procedures supports consistent 12-Lead information across the care continuum (physical exam, CXR, echocardiography, emergency resuscitation etc.)


Ability to capture dynamic changes that may be missed using an ECG cart, since transient events of diagnostic/therapeutic importance may not persist long enough to capture.

With EASI, transient events can be documented with full 12-Lead ECG under continuous monitoring conditions.


When compared to standard 12-Lead ECG’s, EASI derived 12-Lead is diagnostically comparable for detection of cardiac arrhythmias, myocardial ischemia, and myocardial infarction (the most common clinical applications for cardiac monitoring)

How Good is EASIHow Good is EASI® 12 Lead® 12 Lead 99% correlation between standard ECG

monitoring and EASI for Ischemia Excellent agreement between 2 methods for Rate,

Rhythm and Intervals Perfect agreement for Arrhythmia recognition 84-99% correlation for Axis determination 90% and above for acute and prior MI

recognition (Undetermined for atrial enlargement and

ventricular hypertrophy … chronic conditions)

Interpreting the Interpreting the EASIEASI® 12 Lead® 12 Lead

The derived EASI 12-lead is approached the same way as a standard 12-lead … all principles remain the same in terms of interpretation.

EASI should be used as a trending tool & as a dynamic clinical assessment tool (Monitoring)

Baseline EASI 12-lead should be compared to any changes, as is done with a conventional 12-lead.

EASI 12-lead is not meant to replace a standard 12-lead in terms of diagnostic value, but used in combination as a clinical assessment tool.

Technical ConsiderationsTechnical Considerations

Lead Placement & Vectors (Thoracic versus Limb)

Millivolt and StandardFilters

Back to the Application Stuff!Back to the Application Stuff!

Clinical Correlation: Clinical Correlation: Arterial Blood Supply & ECGArterial Blood Supply & ECG

Right VentricleRight Ventricle

Right Coronary Artery (RCA)

Inferior Wall of Left VentricleInferior Wall of Left Ventricle

Right Coronary Artery (RCA)

Posterior Wall of Left VentriclePosterior Wall of Left Ventricle

Right Coronary Artery (RCA)(Left Circumflex)

Anterior Wall of Left VentricleAnterior Wall of Left Ventricle

Left Anterior Descending (LAD) branch of Left Coronary Artery

Septal Branch

Lateral Wall of Left VentricleLateral Wall of Left Ventricle

Circumflex branch of Left Coronary Artery

ApexApex

RCA or LAD or Circumflex

A Diagrammatic PerspectiveA Diagrammatic Perspective

It is the LEFT ventricle which contributes the forces when viewing the 12 Lead ECG

Cube ConceptCube Concept

Septal/Anterior

Apical

Lateral

Inferior

Endocardial

(Posterior)

Each “face” of the cube represents a different Left Ventricular wall

Right

Ventri cle

Inferior LeadsInferior Leads

Leads II, III and aVF

Leads III, aVF, II

Anterior or Anteroseptal LeadsAnterior or Anteroseptal Leads

V1 through V6 (septal + anterior + apical)V1-V2 Septal; V3-V4 Anterior or Mid-

Precordial;V5-V6 Apical

V1, V2, V3, V4 and V5, V6

Apical (Low Lateral) LeadsApical (Low Lateral) Leads

V5 and V6(Lead II)

Lateral LeadsLateral Leads

Lead I and aVL

(Posterior Leads)(Posterior Leads)

Viewed as mirror-image changes in V1-V2

Endocardial LeadsEndocardial Leads

aVR!(aVL on occasion)

Right Ventricular LeadsRight Ventricular Leads

V3R and V4R!!(ST > Lead III than in Lead II and aVF)*

The “Cone” PerspectiveThe “Cone” Perspective

L. Schamroth

““OtherOther Fundamentals" Fundamentals"

Polarity

PolarityPolarity

An impulse traveling toward a positive electrode will be recorded as positive … an impulse traveling away from a positive electrode will be recorded as negative

There are, however, varying degrees of positivity and negativity represented by various ECG waveforms

PolarityPolarity

A lead measures electrical activity within an electrical field

The field is divided into a positive half and a negative half

Any impulse that falls within the positive half of the electrical field will result in a positive complex, and any that fall within the negative half will result in a negative complex.

Positive & Negative FieldsPositive & Negative Fields

The more PARALLEL the impulse is to the lead orientation, the TALLER the complex.

As the impulse becomes more PERPENDICULAR to the lead orientation, it becomes more ISOELECTRIC

ExploringExploring the the Electrical Electrical Activation of the HeartActivation of the Heart

Wave of DepolarizationWave of Depolarization

The anatomic position of the heart must also be considered, since it is the actual position of the heart that influences the net direction of electrical activity.

It is this NET direction that is recorded on the ECG


Frontal Plane view of mean wave of depolarization

Left-sided leads will record the activity opposite to Right-sided leads


Even on a single plane, electrical activity can be viewed in several directions at once.

Imagine a “tug-of-war” between the LV and RV

Ventricular DominanceVentricular Dominance

To apply this concept to venticular activation, recall that the right ventricle is a thin-walled chamber with only one conduction pathway.

The left ventricle is a thicker muscle mass and has two branches in it’s conduction system.

Net Direction or VectorNet Direction or Vector

Even though the electrical activity of the heart is travelling in many directions at once, one general direction predominates and can be determined by averaging all of the forces.

Normal Components Normal Components && Vectors Vectors

Introducing the 12 Lead Introducing the 12 Lead ElectrocardiogramElectrocardiogram

“Mapping the Heart’s Spark”

"The Traditional 12 Leads""The Traditional 12 Leads"

FRONTAL PLANE:

I

II

III

aVR

aVL

aVF

Lead I (Lateral)Lead I (Lateral)0 degrees (LCx)0 degrees (LCx)

RA- …. LA+P uprightQ small or noneR dominantS < R or noneST Isoelectric (+1 to –0.5)T upright

Lead II (Inferior/Left)Lead II (Inferior/Left)+ 60 degrees (RCA)+ 60 degrees (RCA)

RA- …. LL+P uprightQ small or noneR dominantS < R or noneST Isoelectric (+1 to –0.5)T upright

Lead III (Inferior/Right)Lead III (Inferior/Right)+120 (RCA)+120 (RCA)

LA- … LL+P upright, flat, diphasic, invertedQ small or noneR none, diphasic to dominantS none to dominantST Isoelectric (+1 to –0.5)T upright, flat, diphasis, inverted

Lead aVR (Endocardial)Lead aVR (Endocardial)- 150 degrees (global)- 150 degrees (global)

RA+P invertedQ small, none, largeR small or noneS dominantST Isoelectric (+1 to –0.5)T inverted

Lead aVL (Lateral)Lead aVL (Lateral)- 30 degrees (LCx)- 30 degrees (LCx)

LL+P upright, flat, diphasic, invertedQ small, none, largeR small, none, dominantS small, none, dominantST Isoelectric (+1 to –0.5)T upright, flat, diphasic, inverted

Lead aVF (Inferior)Lead aVF (Inferior)+90 degrees (RCA)+90 degrees (RCA)

LL+P upright, flat, diphasic, invertedQ small or noneR small, none, dominantS small, none, dominantST Isoelectric (+1 to –0.5)T upright

"The Traditional 12 Leads""The Traditional 12 Leads"

HORIZONTAL PLANE:

V1

V2

V3

V4

V5

V6

Lead V1 (Septal)Lead V1 (Septal)LAD-Septal branchLAD-Septal branch

4 ICS RSBP upright, flat, diphasicQ none, may be QSR < S or noneS dominantST 0 to +3T upright, flat, diphasic, inverted

Lead V2 (Septal)Lead V2 (Septal)LAD-Septal branchLAD-Septal branch

4 ICS LSBP uprightQ noneR < SS dominantST 0 to +3T upright, diphasic, inverted

Lead V3 (Anterior)Lead V3 (Anterior)LADLAD

Between V2 and V4P uprightQ small or noneR ~ SS ~ RST 0 to +3T upright

Lead V4 (Anterior)Lead V4 (Anterior)LADLAD

5ICS LMCLP uprightQ small or noneR > SS < RST +1 to 0.5T upright

Lead V5 (Apical)Lead V5 (Apical)VariableVariable

5ICS LAALP uprightQ smallR DominantS small (< V4)ST +1 to 0.5T upright

Lead V6 (Apical)Lead V6 (Apical)VariableVariable

5ICS MALP uprightQ smallR DominantS noneST +1 to 0.5T upright

“Putting the Leads Together”

Frontal Plane

Horizontal Plane

““AdditionalAdditional Leads" Leads"

HORIZONTAL PLANE: Right-Sided Leads

V1R

V2R

V3R

V4R

V5R

V6R

““AdditionalAdditional Leads" Leads"

HORIZONTAL PLANE: Posterior Leads

V7

V8

V9

"Systematic Approach" "Systematic Approach" to the Electrocardiogramto the Electrocardiogram

A Systematic ApproachA Systematic Approach

Establish underlying rhythm (atrial & ventricular rates, PR interval, AV conduction)

Measure the QRS (including VAT) and QT interval

Determine the Mean Frontal Plane Axis


Screen For: Conduction Delays (based on prior assessment)

– Atrioventricular and/or Intraventricular Presence of Ischemia, Injury & Infarction Endocardial or Epicardial abnormalities Chamber Enlargement

– Atrial and/or Ventricular Other

– Electrolyte Abnormalities– Drug Effects


Interpretation and Documentation:Primary RhythmConduction DisturbancesSecondary Rhythm (e.g. junctional escape)Other abnormalities (ST, T, QT)

Significance?

Management?

The Electrical AxisThe Electrical Axis

Axis … No Problem!Axis … No Problem!


Intensity and direction that the electrical impulse takes during depolarization & repolarization

The general, mean or dominant direction of the various vectors is known as the MEAN VECTOR, and electrocardiographically as the MEAN QRS AXIS


The electrical axis is determined by:MagnitudeDirectionPolarity

It’s direction is determined from the frontal plane (“rotation” on the horizontal plane)

Significance of the Significance of the Electrical AxisElectrical Axis

“The use of the Electrical axis in the clinical interpretation of the electrocardiogram constitutes a most important diagnostic procedure and elevates electrocardiographic interpretation from the empirical to the deductive.”

Leo Schamroth. The Electrical Axis. It’s determination and significance.

Application of QRS AxisApplication of QRS Axis

Differentiation of different types of MI’sVentricular DominanceVentricular Ectopy vs AberrancyHemiblocksPacemaker FunctionW-P-W SyndromeDextrocardia

(Application of P Wave Axis)(Application of P Wave Axis)

P pulmonaleP congenitaleRetrograde activation of the atrium

(Application of T Wave Axis)(Application of T Wave Axis)

Ventricular hypertrophyCoronary insufficiencyFully evolved phase of acute myocardial

infarction

(Application of ST Axis)(Application of ST Axis)

InfarctionSubendocardial vs. Subepicardial injury

Calculating the Mean Calculating the Mean QRS AxisQRS Axis

Determination of the AxisDetermination of the Axis

There are several methods for estimation of the frontal plane axis.

Ideal method would be both the most simplistic and accurate, thus lending itself to efficient clinical application.

Steps for Calculation of AxisSteps for Calculation of Axis

1. Most equiphasic or smallest complex on frontal plane?

2. Which lead is 900 (perpendicular) to this lead?

3. Is this lead mostly positive or negative? If positive, go to the positive pole … if negative, go to the negative pole

4. Axis?

Lead AssociationsLead Associations

For any lead, there is another lead that is always perpendicular to it, and visa versa

Perpendicular to a bipolar lead is always an associated unipolar lead, and visa versa

Example: look at Lead II … what lead is perpendicular to Lead II? (Lead II also then must divide that lead into a positive and a negative field)

Quick AssociationQuick Association

Memory TrickMemory Trick

I … aVF

II … aVL

III … aVR

Determination of AxisDetermination of Axis

Abnormal Axis or Abnormal Axis or Reversed Reversed Arm ElectrodesArm Electrodes?!??!?


1

2


3

4


5

6


7

8


9

10

Determination of the Determination of the Electrical AxisElectrical Axis

Axis DeviationAxis Deviation

ECG Patterns of Ischemia, ECG Patterns of Ischemia, Injury Injury && Infarct Infarct

Clinical Recognition

Ischemia, Injury & InfarctIschemia, Injury & Infarct

Myocardial Oxygenation– Supply– Demand

Regional versus Global deficits


Myocardial ischemia is often missed in cases of silent ischemia

ST segment monitoring, though not the most specific or sensitive, is the only technology that can be applied continuously (it is also non-invasive)

Silent Ischemia is as clinically significant as that associated with chest pain … Total!


One must also correlate the coronary arterial blood supply to the various structures to the regions on the ECG and other clinical considerations …

Without making this correlation, clinical significance of ECG changes is questionable.

Right Coronary ArteryRight Coronary ArteryRight AtriumRight VentricleInferior wall of Left VentriclePosterior wall of Left VentriclePosterior 1/3 of Intra-Ventricular SeptumSA node in 65% of populationAV node in 90% of populationPosteroinferior Division of Left Bundle

Branch

Left Anterior Descending Left Anterior Descending Branch of Left Coronary ArteryBranch of Left Coronary ArteryAnterior wall of Left VentricleAnterior 2/3 of Intra-Ventricular Septum(Apex of the Left Ventricle)Bundle of HisRight Bundle BranchBoth Divisions of Left Bundle Branch

Left Circumflex Branch of Left Left Circumflex Branch of Left Coronary ArteryCoronary Artery

Left AtriumLateral wall of Left Ventricle(Posterior wall of Left Ventricle)(Posterior 1/3 of Intra-Ventricular Septum)SA node in 45% of populationAV node in 10% of population

Coronary CirculationCoronary Circulation

One must remember that this is a general description of coronary circulation, and applies to the majority of the population.

Individual variations in the coronary vasculature are infinite, which explains the varying ECG manifestations that may be seen!

ECG ManifestationsECG Manifestations

The surface electrocardiogram (ECG) is the most common noninvasive diagnostic technique utilized to determine the presence and location of myocardial infarction.

The limitations include not having enough leads to view all regions, being an intermittent assessment, and non-specific findings.

The ECG as a Diagnostic ToolThe ECG as a Diagnostic Tool

The ECG is but one clinical assessment tool used in the diagnosis of Acute Myocardial Ischemia, Injury and Infarction.

Used in combination with History, Clinical Assessment and Biochemical Markers, it becomes an invaluable tool.

ZonesZonesInfarct, Injury & IschmiaInfarct, Injury & Ischmia

Note: Degree of involvement between Endocardium and Epicardium

Continuous ST-Segment Continuous ST-Segment Monitoring: Monitoring:

Protocol for PracticeProtocol for Practice

Repolarization the Key!Repolarization the Key!

Repolarization requires sufficient energy in the form of ATP …

The Ventricular repolarization process is normally reflected by the T wave (and U wave)

Early repolarization abnormalities will manifest itself in the ST segment … resulting in ST segment changes (repolarization wave shifts leftward)

What is Isoelectric?What is Isoelectric?

T-P Segment is preferable

What is ST Deviation?What is ST Deviation?

ST Segment MonitoringST Segment Monitoring

Ideally, ST segment monitoring should also be done on a continuous basis in order to continuously monitor & evaluate patient progress.

Continuous computerized ST segment monitoring is available for all 12 Leads using “EASI 12 Lead” (5 Electrodes) or via a Modified 12 Lead (10 Electrodes) using specific algorithms.


ST Index: avF, V2 and V5 (common lead combination for detection of acute ischemia or injury)

Offers 98.4% sensitivity for acute ischemic events Increased sensitivity (99.3%) using Leads

III/V2/V5 or III/V2/V4 Lead III is more sensitive for RV changes than

avF!


If an alarm is triggered due to an ST segment change, only a clinician, not the monitor, can determine the seriousness of the event.

To ensure peak performance, the staff should be aware of the interventions and adjustments they can implement to enhance the ST algorithm’s performance & accuracy!

CAUTION …CAUTION …ECG Settings!ECG Settings!

Sometimes it Hard to Tell Sometimes it Hard to Tell What’s What … They Look What’s What … They Look

Similar!Similar!

Epicardial versus Epicardial versus Endocardial?Endocardial?

Ischemia & Injury Ischemia & Injury PatternsPatterns

ST’s up or down?ST’s up or down?

ST depression … endocardial involvementST elevation … epicardial involvement

From Who’s Perspective?From Who’s Perspective?aVR = Endocardial Lead

(sometimes aVL also)

All other Leads = Epicardial Leads

ST changes Transient or ST changes Transient or Persistent?Persistent?

Transient ST changes … Anginal syndromes

Persistent ST changes … Infarction process (Rule out Aneurysm, Pericarditis)

Regional or Global Regional or Global ST Changes?ST Changes?

Isolated to a specific region (remember correlation to coronary arterial supply)

Widespread ST segment and/or T wave changes may be seen in such conditions as Pericarditis and Coronary Insufficiency.

Persistent ST Elevation Persistent ST Elevation Concave or Convex?Concave or Convex?

Pericarditis-concave … Infarction-convex

QT Short? QT Long?

Acute PericarditisAcute Pericarditis

Indicative versus Reciprocal Indicative versus Reciprocal ST ChangesST Changes

Remember the cube concept … opposite walls can show the opposite changes. Remember also, associated leads (I/aVF, II/aVL, III/aVR) will

ST elevation in one wall will show ST depression in the opposite wall

If you can turn the ST “upside down” from one set of leads and match it to the ST in the opposing wall, it’s most likely reciprocal … rather than a separate process associated with a different coronary artery.

Reciprocal LeadsReciprocal LeadsThink “Inside the Box”Think “Inside the Box”

Apex

Reciprocal PatternsReciprocal Patterns

Question: If a transmural infarct is on in the inferior wall, which leads will show a reciprocal ST depression?

Can ST’s look abnormal in the Can ST’s look abnormal in the Healthy Heart?Healthy Heart?

Early repolarization can often be found as a normal variant, especially in the young, blacks and athletes … this can mimic pericarditis

Can also occur in rapid heart ratesLook at baselines and trends!Be aware of normal variants

Manifestations of Myocardial Manifestations of Myocardial IschemiaIschemia

Subendocardial Myocardial Ischemia (Classic Angina):– Transient ST segment depression in the leads

facing the area– T wave changes

Physiologic vs. Pathologic S-T Physiologic vs. Pathologic S-T Segment DepressionSegment Depression

Myocardial Ischemia – Myocardial Ischemia – Coronary InsufficiencyCoronary Insufficiency

Pathological junctional ST segment depression

Hyperacute T-wave (tall, peaked & symmetrical)

U-wave inversion

Exercise-Induced IschemiaExercise-Induced Ischemia

Manifestations of Myocardial Manifestations of Myocardial IschemiaIschemia

Prinzmetal’s (Variant) Angina:– Transient ST segment elevation in the leads

facing the area– ST elevation (injury pattern involving full

thickness of myocardium up to and including the epicardium)

– Convex ST shape– (R wave often increases in amplitude in an

injury pattern)

Variant Angina (Prinzmetal’s)Variant Angina (Prinzmetal’s)

A. During pain B. A few minutes after pain resolved

Infarction with or without Infarction with or without ST elevation?ST elevation?

STEMI … ST-Elevated (Acute) MINSTEMI …. Non-ST-Elevated (Acute) MI

IIdentifying the dentifying the “Non-“Non-TransmuralTransmural” or ” or

Non-ST-ElevatedNon-ST-ElevatedMMyocardial Infarctionyocardial Infarction

Non-ST-Elevated MI Non-ST-Elevated MI (NSTEMI)(NSTEMI)

Persistent ST depressions and/orPersistent T wave inversionNo Q waveLoss of R wave amplitude

Non-ST-Elevated MINon-ST-Elevated MI

NSTEMINSTEMI

IIdentifying the dentifying the ““TransmuralTransmural” or ” or ST-ElevatedST-Elevated

Myocardial InfarctionMyocardial Infarction

ST-Elevated MI (STEMI)ST-Elevated MI (STEMI)

Persistent ST elevation and/orHyperacute T-wave changes … progressing

to T-wave inversionDevelopment of a pathological Q wave (if

untreated)Loss of R wave amplitude

Evolving Inferior Wall STEMIEvolving Inferior Wall STEMI

Why a Q wave?Why a Q wave?

The “Electrical Window” Concept

Why Not a Q wave?Why Not a Q wave?

Loss of R wave amplitude is just as significant!

Locating the Area of InfarctionLocating the Area of Infarction

ECG Manifestations and

Clinical Implications

I Should Be Able to do This … I Should Be Able to do This … Right!?!Right!?!

ST SegmentsST Segments

ST Trending and Mapping – Expanding our Clinical

Monitoring for ACS

Acknowledgement: Philips Medical Systems – ST MapTM

Continuous ST Segment Continuous ST Segment MonitoringMonitoring

(2009)

ST Segment Monitoring – ST Segment Monitoring – Widely Underused!Widely Underused!

CLASS I:Acute Coronary SyndromesChest Pain or Anginal Equivalent

SyndromesPTCA with suboptimal Angiographic

resultsVariant Angina (Coronary Vasospasm)

ST Segment Monitoring – ST Segment Monitoring – Widely Underused!Widely Underused!

CLASS II:Postacute MINon-urgent Percutaneous Coronary

InterventionHigh Risk for Ischemia after Cardiac or

Noncardiac SurgeryHigh Risk for Ischemia resulting from

Congential or Acquired Conditions (eg. Trauma, Cardiotoxic drugs, Myocarditis …)

ST Segment Monitoring – ST Segment Monitoring – Technically more difficult …Technically more difficult …

CLASS III:LBBB, or intermittent RBBBVentricular Paced RhythmRhythms that Obscure the ST segment

(coarse atrial fibrillation or flutter)

Remember that ST segment deviation is not always an indication of ischemia/infarction…

ST elevation Myocardial injury Pericarditis Dyskinetic ventricle Ventricular aneurysm

(persistent V1-V4) J-point elevation (normal young

patients)

ST depression Ischemia Tachycardia Subendocardial infarction Posterior wall MI (reciprocal) Carbon monoxide poisoning Antiarrythmic drugs (eg.

Lanoxin) Mitral valve prolapse Wolf-Parkison-White syndrome Hypokalemia

Who is using ST segment Who is using ST segment monitoring?monitoring?

Nursing survey in 2001 found… Only 50% units are using ST segment monitoring consistently

Attributed to: – staff skill level; lack of expertise for interpretation; “trickle” down effect (from

research to bedside implementation); Too many false alarms; Cost prohibitive; Clinician appreciation of measurement

“We hypothesized that ST segment monitoring, although clearly sensitive for detecting myocardial ischemia, may not provide

clinically useful information in a user-friendly manner”

Survey of use of ST-segment monitoring in patients with acute coronary syndromesPatton et al, AJCC Vol 10, No1, Pg 23-34

ST Segment displays…ST Segment displays…

A nice overview but what about…

Assistance with pattern recognition.

The location of the ST changes.

The evolution of the ST changes.

12-Lead Display screen

ST Baseline Window

ST Segment Display Screen

Cardiologists & Continuous Cardiologists & Continuous ST-Segment MonitoringST-Segment Monitoring

“ST Map” offers a solution…

ST “Map” = ST “Multivariate Axis Plotting”

““ST Map”ST Map”™™

ENHANCED CLINICAL RECOGNITION!Assists with Pattern Recognition (more

intuitive)Assists with Locating the area of

involvement (diagrammatic representation)Assists with trending, showing evolutionary

changes

Eindhoven’s Triangle

Frontal Plane LeadsFrontal Plane Leads

Limb Leads

Augmented Limb Leads

Inferior

Superior

Lef

tRight

Horizontal Plane LeadsHorizontal Plane Leads

Precordial (Chest) Leads

Posterior

Anterior

Lef

t

Rig

ht

Creating the Multivariate Axis Creating the Multivariate Axis Plot (Map)Plot (Map)

Creating the Multivariate PlotCreating the Multivariate Plot

…the complete picture (Frontal & Horizontal)

Limb Leads Chest Leads

(Must have minimum of 3 leads active for the ST Map to be displayed - i.e 3 chest leads for chest map, 3 limb leads for limb map)

Inferior

Apical

Septal

Lateral

Anterior

Clinical and ECG Correlation…Clinical and ECG Correlation…

Anterior view

Location Leads Reciprocal Artery involved

ST elevation ST depression

Inferior II, III, aVF I, aVL Right Coronary Artery

Lateral I, aVL, (V5, V6) V1, V2 Circumflex

Large Anterior V1, V2, V3, V4, I, aVL II, III, aVF Left Coronary Artery

Anterolateral I, aVL, V4, V5, V6 II, III, aVF Left Anterior Descending

Anteroseptal V1, V2, V3 None Left Anterior Descending

ST Map on the 12-lead DisplayST Map on the 12-lead Display

ST Map (Current) WindowST Map (Current) Window

To hide baseline

ST Map (Trend) WindowST Map (Trend) Window

Sends the content of the ST Map window to the configured printer.

ST (Current) PrintoutST (Current) Printout

ST (Trend) PrintoutST (Trend) Printout

ST Map report for ST Map report for documentation…documentation…

Application of ST MapApplication of ST Map

A Case StudyA Case Study

Clinical Application of ST Segment Trending using “ST Map”

Case StudyCase StudyA 62-year-old male presents to the Emergency Room with a

two-hour history of developing chest pain while gardening.

On arrival, patient is anxious, pale and sweating. He is also nauseated and states he feels dizzy, complaining of chest & jaw pain (pain score 4 out 5) associated

with left arm numbness.

The patient is connected to the monitor & the following vital signs are recorded:

HR 62

RR 28 (SpO2 97%)

BP 90/50

T 369

ST Map shows the following localization…

ST Map current view in acute ST Map current view in acute phase…phase…

ST ElevationST Depression

ST ElevationST Depression

12 lead ECG on arrival in the 12 lead ECG on arrival in the Emergency RoomEmergency Room

Location of ST changes on the Location of ST changes on the ECG…ECG…

Location Leads Reciprocal Artery involved

ST elevation ST depression

Inferior II, III, aVF I, aVL Right Coronary Artery

Lateral I, aVL, V5, V6 V1, V2 Circumflex

Anterior V1, V2, V3, V4, I, aVL II, III, aVF Left Coronary Artery

Anterolateral I, aVL, V4, V5, V6 II, III, aVF Left Anterior Descending

Anteroseptal V1, V2, V3 None Left Anterior Descending

After evaluating the presenting symptoms, strong family history, & 12 lead ECG changes

a diagnosis of acute inferior myocardial infarction is made.

The patient is prepared for an emergency angiography with possible angioplasty.

ST Map current view using ST Map current view using reference baseline to monitor for reference baseline to monitor for

changes during angioplasty…changes during angioplasty…

Reference baseline

ST Elevation

Angiogram showed a 85% occlusion of proximal right coronary artery and a coronary stent was successfully deployed. ReoPro™ was given as

per hospital guidelines.

The patient’s condition is stable and he is transferred to the Coronary Care Unit for close

observation.

Three hours post angioplasty…Three hours post angioplasty…

ST Elevation

Using ST Map trends for Using ST Map trends for continued management…continued management…

12 hours post angioplasty, the patient had a brief episode of central non-radiating chest pain at rest not

associated with any other signs and symptoms.

The trending feature on the ST Map was set for 12 second snapshots to observe closely the changes in

the ST segments.

The pain resolved spontaneously.

ST Map trends using 12 second ST Map trends using 12 second snapshots to observe closely ST snapshots to observe closely ST

changes…changes…

This episode of chest pain resolved spontaneously and the patient remained pain-

free.

The ST Map at 24hrs post angioplasty, showed that the inferior ST segments, were nearly

back to normal and that the lateral changes had resolved completely.

ST Map at 24 hours shows the ST Map at 24 hours shows the ST changes nearly back to ST changes nearly back to

normal…normal…

12 lead serial ECG confirms ST 12 lead serial ECG confirms ST Map findings…Map findings…

Residual Q wave & T wave inversion

The patient remained pain-free for the remainder of his stay in the CCU. After spending time on the telemetry floor, the patient was discharged

home 7 days post angioplasty.

“Using ST MapTM for monitoring ST segment monitoring, provides clinically useful information in a user-friendly manner”

Survey of use of ST-segment monitoring in patients with acute coronary syndromesPatton et al, AJCC Vol 10, No1, Pg 23-34

TM Philips Medical Systems

Identifying Intraventricular Identifying Intraventricular Conduction DefectsConduction Defects

RBBB, LBBB, LAH, LPH, Bifascicular & Trifascicular Blocks

Remember the Basics!Remember the Basics!


Normally Left before Right!



Right Bundle Branch BlockRight Bundle Branch Block

Right Bundle Branch BlockRight Bundle Branch Block

Normal variant Ischemic heart disease Acute myocardial infarction Acute coronary insufficiency Trauma Acute heart failure Intracardiac catheter (PA catheter) Right heart catheterization

Causes of RBBBCauses of RBBB

CardiomyopathyDegenerative disease of the conduction

systemAcute Infective processesParasitesRheumatic heart, Syphilis, Tumors,

Congenital lesionsSurgery (Tetralogy of Fallot, VSD)

Salient Features of RBBBSalient Features of RBBB

Wide QRS (> .10 sec)Increased VAT (> 0.04 sec) in RV leadsrsR’ or qR in V1T opposite polarity to QRS in RV leadsWide S wave in left-sided leads (V6, I, II)

Left Bundle Branch BlockLeft Bundle Branch Block

Causes of LBBBCauses of LBBB

Not as common as Right Bundle Branch Block due to two separate fascicles (posterior fascicle has a dual blood supply and is much thicker)

Causes are the same as for Right Bundle Branch Block, but involving the Left Ventricle or Surgery to the Aortic Valve.

Salient Features of LBBBSalient Features of LBBB

Wide QRS (> .10 sec)Increased VAT (> 0.04 sec) in LV leadsWide R or notched “M-shaped R” in Left-

sided leads (V5, V6, I, aVL, II)T opposite polarity to QRS in LV leadsWide S or QS wave in right-sided leads

(V1)

The Ultimate Test!The Ultimate Test!

To be continued …To be continued …

I’m 100% saturated!I’m 100% saturated!

Thank you!Thank you!

Health & Medicine

Demystifying clinical electrocardiography august, 2013