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ECG

ECG Basics

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Objectives

To recognize the normal rhythm of theheart - Normal Sinus Rhythm.

To recognize the 13 most commonrhythm disturbances.

To recognize an acute myocardialinfarction on a 12-lead ECG.

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Normal Impulse ConductionSinoatrial node

AV node

Bundle of His

Bundle Branches

Purkinje fibers

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The PQRST

P wave - Atrial

depolarization

T wave - Ventricularrepolarization

QRS - Ventriculardepolarization

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The PR Interval

Atrial depolarization+

delay in AV junction(AV node/Bundle of His)

(delay allows time forthe atria to contractbefore the ventricles

contract)

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Pacemakers of the Heart

SA Node - Dominant pacemaker with anintrinsic rate of 60 - 100 beats/minute.

AV Node - Back-up pacemaker with anintrinsic rate of 40 - 60 beats/minute.

Ventricular cells - Back-up pacemakerwith an intrinsic rate of 20 - 45 bpm.

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The ECG Paper

Horizontally One small box - 0.04 s One large box - 0.20 s

Vertically One large box - 0.5 mV

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Every 3 seconds (15 large boxes) ismarked by a vertical line.

This helps when calculating the heart

rate.NOTE: the following strips are not marked

but all are 6 seconds long.

3 sec 3 sec

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Reading 12-Lead ECGs

The best way to read 12-lead ECGs is to develop a step-by-step approach (just as we did for analyzing a rhythmstrip). In these modules we present a 6-step approach:

1. Calculate RATE2. Determine RHYTHM3. Determine QRS AXIS

4. Calculate INTERVALS5. Assess for HYPERTROPHY6. Look for evidence of INFARCTION

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Rhythm Analysis

Step 1: Calculate rate. Step 2: Determine regularity.

Step 3: Assess the P waves. Step 4: Determine PR interval. Step 5: Determine QRS duration.

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Step 1: Calculate Rate

Option 1 Count the # of R waves in a 6 second

rhythm strip, then multiply by 10. Reminder: all rhythm strips in the Modules

are 6 seconds in length.

Interpretation? 9 x 10 = 90 bpm

3 sec 3 sec

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Option 2 Find a R wave that lands on a bold line.

Count the # of large boxes to the next Rwave. If the second R wave is 1 large boxaway the rate is 300, 2 boxes - 150, 3boxes - 100, 4 boxes - 75, etc. (cont)

R wave

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Option 2 (cont) Memorize the sequence:

300 - 150 - 100 - 75 - 60 - 50

Interpretation?

300

150

100

75

60

50

Approx. 1 box less than

100 = 95 bpm

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Step 2: Determine regularity

Look at the R-R distances (using a caliper ormarkings on a pen or paper).

Regular (are they equidistant apart)?

Occasionally irregular? Regularly irregular?Irregularly irregular?

Interpretation? Regular

R R

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Step 3: Assess the P waves

Are there P waves? Do the P waves all look alike?

Do the P waves occur at a regular rate? Is there one P wave before each QRS?

Interpretation? Normal P waves with 1 P

wave for every QRS

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Step 4: Determine PR interval

Normal: 0.12 - 0.20 seconds.(3 - 5 boxes)

Interpretation? 0.12 seconds

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Step 5: QRS duration

Normal: 0.04 - 0.12 seconds.(1 - 3 boxes)

Interpretation? 0.08 seconds

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Normal Sinus Rhythm (NSR)

Etiology: the electrical impulse is formedin the SA node and conducted normally.

This is the normal rhythm of the heart;

other rhythms that do not conduct viathe typical pathway are calledarrhythmias.

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NSR Parameters

Rate 60 - 100 bpm

Regularity regular P waves normal PR interval 0.12 - 0.20 s

QRS duration 0.04 - 0.12 s Any deviation from above is sinus

tachycardia, sinus bradycardia or an

arrhythmia

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Intervals

Intervals refers to the length of the PR and QT intervalsand the width of the QRS complexes. You should havealready determined the PR and QRS during the rhythmstep, but if not, do so in this step.

In the following few slides well review what is a normaland abnormal PR, QRS and QT interval. Also listed are a

few common causes of abnormal intervals.

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PR interval

< 0.12 s 0.12-0.20 s > 0.20 s

High catecholaminestates

Wolff-Parkinson-WhiteNormal AV nodal blocks

Wolff-Parkinson-White 1st Degree AV Block

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QRS complex

< 0.10 s 0.10-0.12 s > 0.12 s

Normal Incomplete bundlebranch block

Bundle branch blockPVC

Ventricular rhythm

3 rd degree AV block withventricular escape rhythm

Incomplete bundle branch block

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Axis Axis refers to the mean QRS axis (or vector) during ventriculardepolarization. As you recall when the ventricles depolarize (in anormal heart) the direction of current flows leftward and downwardbecause most of the ventricular mass is in the left ventricle. We liketo know the QRS axis because an abnormal axis can suggestdisease such as pulmonary hypertension from a pulmonaryembolism.

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FRONTAL

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The QRS axis is determined by overlying a circle, in the frontalplane. By convention, the degrees of the circle are as shown.

The normal QRS axis lies between -30 o and +90 o.

0o

30 o

-30 o

60 o

-60 o-90 o

-120 o

90 o 120 o

150 o

180o

-150 o

A QRS axis that falls between -30 o and -90 o is

abnormal and called leftaxis deviation .

A QRS axis that fallsbetween +90 o and +150 o

is abnormal and calledright axis deviation . A QRS axis that fallsbetween +150 o and -90 o isabnormal and calledsuperior right axis deviation .

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We can quickly determine whether the QRS axis isnormal by looking at leads I and II.

If the QRS complex isoverall positive (R > Q+S) in leads I and II, the QRSaxis is normal .

QRS negative (R < Q+S)

In this ECG what leadshave QRS complexesthat are negative?equivocal?

QRS equivocal (R = Q+S)

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How do we know the axis is normal when the QRS

complexes are positive in leads I and II?

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The answer lies in the fact that each frontal leadcorresponds to a location on the circle.

0o

30 o

-30 o

60 o

-60 o-90 o

-120 o

90 o 120 o

150 o

180o

-150 o

I

IIav

avL

avR

Limb leads

I = +0 o

II = +60 o

III = +120 o

Augmented leadsavL = -30 o

avF = +90 o

avR = -150 o

I

IIIII

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0o

30 o

-30 o

60 o

-60 o-90o

-120 o

90 o 120 o

150 o

180 o

-150 o

Since lead I is orientated at 0 o a wave of depolarization directed towardsit will result in a positive QRS axis. Therefore any mean QRS vectorbetween -90 o and +90 o will be positive.

I

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0o

30 o

-30 o

60 o

-60 o-90o

-120 o

90 o 120 o

150 o

180 o

-150 o


Similarly, since lead II isorientated at 60 o a wave ofdepolarization directed towardsit will result in a positive QRS

axis. Therefore any mean QRSvector between -30 o and +150 o will be positive.

I

II

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0o

30 o

-30 o

60 o

-60 o-90o

-120 o

90 o 120 o

150 o

180 o

-150 o


Similarly, since lead II isorientated at 60 o a wave ofdepolarization directed towardsit will result in a positive QRS

axis. Therefore any mean QRSvector between -30 o and +150 o will be positive.

Therefore, if the QRS complex

is positive in both leads I andII the QRS axis must bebetween -30 o and 90 o (whereleads I and II overlap) and, as

a result, the axis must benormal.

I

II

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0o

30 o

-30 o

60 o

-60 o-90o

-120 o

90 o 120 o

150 o

180 o

-150 o

0o

30 o

-30 o

60 o

-60 o-90o

-120 o

90 o 120 o

150 o

180 o

-150 o

Now using what you just learned fill in the following table. For example, ifthe QRS is positive in lead I and negative in lead II what is the QRS axis?(normal, left, right or right superior axis deviation)

QRS Complexes

I

AxisI II+ ++ -

normalleft axis deviation

II

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0o

30 o

-30 o

60 o

-60 o-90o

-120 o

90 o 120 o

150 o

180 o

-150 o

0o

30 o

-30 o

60 o

-60 o-90o

-120 o

90 o 120 o

150 o

180 o

-150 o

if the QRS is negative in lead I and positive in lead II what is the QRSaxis? (normal, left, right or right superior axis deviation)

QRS Complexes

I

AxisI II+ ++ -

- +

normalleft axis deviation

right axis deviation

II

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0o

30 o

-30 o

60 o

-60 o-90o

-120 o

90 o 120 o

150 o

180 o

-150 o

if the QRS is negative in lead I and negative in lead II what is the QRSaxis? (normal, left, right or right superior axis deviation)

QRS Complexes

I

AxisI II+ ++ -

- +

- -

normalleft axis deviationright axis deviation

right superioraxis deviation

0o

30 o

-30 o

60 o

-60 o-90o

-120 o

90 o 120 o

150 o

180 o

-150 o

II

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Is the QRS axis normal in this ECG? No, there is left axisdeviation.

The QRS is positive in Iand negative

in II.

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To summarize:

The normal QRS axis falls between -30o

and +90o

because ventriculardepolarization is leftward and downward. Left axis deviation occurs when the axis falls between -30 o and -90 o. Right axis deviation occurs when the axis falls between +90 o and +150 o. Right superior axis deviation occurs when the axis falls between between

+150 o and -90 o.

QRS Complexes

AxisI II

+ +

+ -

- +

- -

normal

left axis deviation

right axis deviation

right superioraxis deviation

A quick way todeterminethe QRS axis is to

look at the QRScomplexes in leads Iand II.

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Hypertrophy

In this step of the 12-lead ECG analysis, we use the ECGto determine if any of the 4 chambers of the heart areenlarged or hypertrophied. We want to determine if thereare any of the following:

Right atrial enlargement (RAE) Left atrial enlargement (LAE) Right ventricular hypertrophy (RVH)

Left ventricular hypertrophy (LVH)

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Right atrial enlargement Take a look at this ECG. What do you notice about the P waves?

The P waves are tall, especially in leads

II, III and avF. Ouch! They would hurt to

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Right atrial enlargement To diagnose RAE you can use the following criteria:

II P > 2.5 mm , or

V1 or V2 P > 1.5 mm

Remember 1 smallbox in height = 1 mm

A cause of RAE is RVH from pulmonary hypertension.

> 2 boxes (in height)

> 1 boxes (in height)

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Left atrial enlargement Take a look at this ECG. What do you notice about the P waves?

The P waves in lead II are notched and

in lead V1 they have a deep and wide

Notched

Negative deflection

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Left atrial enlargement To diagnose LAE you can use the following criteria:

II > 0.04 s (1 box) between notched peaks , or

V1 Neg. deflection > 1 box wide x 1 box deep

Normal LAE

A common cause of LAE is LVH from hypertension.

ventricular hypertrophy

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ventricular hypertrophy

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Right ventricular hypertrophy

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RVH

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Right Ventricular Hypertrophy(RVH) & Right AtrialEnlargement (RAE)-KH

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Right ventricular hypertrophy Take a look at this ECG. What do you notice about the axis and QRS

complexes over the right ventricle (V1, V2)?

There is right axis deviation (negative in I,

positive in II) and there are tall R waves in

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Right ventricular hypertrophy Compare the R waves in V1, V2 from a normal ECG and one from

a person with RVH. Notice the R wave is normally small in V1, V2 because the right

ventricle does not have a lot of muscle mass. But in the hypertrophied right ventricle the R wave is tall in V1, V2.

Normal RVH

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Right ventricular hypertrophy To diagnose RVH you can use the following criteria:

Right axis deviation , and

V1 R wave > 7mm tall

A commoncause of RVHis left heart

failure.

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Left Ventricular

Hypertrophy

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Left Ventricular HypertrophyCompare these two 12-lead ECGs. What standsout as different with the second one?

Normal Left Ventricular Hypertrophy

Answer: The QRS complexes are very tall(increased voltage)

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Left Ventricular HypertrophyWhy is left ventricular hypertrophy characterized by tallQRS complexes?

LVH ECHOcardiogramIncreased QRS voltage

As the heart muscle wall thickens there is an increase inelectrical forces moving through the myocardium resultingin increased QRS voltage.

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Left Ventricular Hypertrophy Criteria exists to diagnose LVH using a 12-lead ECG.

For example: The R wave in V5 or V6 plus the S wave in V1 or V2

exceeds 35 mm.

However, for now, allyou need to know isthat the QRS voltage

increases with LVH.

Left ventricular hypertrophy

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Left ventricular hypertrophy Take a look at this ECG. What do you notice about the axis and QRS

complexes over the left ventricle (V5, V6) and right ventricle (V1, V2)?

There is left axis deviation (positive in I, negativein II) and there are tall R waves in V5, V6 and

deep S waves in V1, V2.

The deep S wavesseen in the leads overthe right ventricle arecreated because theheart is depolarizingleft, superior andposterior (away fromleads V1, V2).

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Left ventricular hypertrophy To diagnose LVH you can use the following criteria *:

R in V5 (or V6) + S in V1 (or V2) > 35 mm , or

avL R > 13 mm

A common cause of LVHis hypertension.

* There are severalother criteria for thediagnosis of LVH.

S = 13 mm

R = 25 mm

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A 63 yo man has longstanding, uncontrolled hypertension. Is there evidenceof heart disease from his hypertension? (Hint: There a 3 abnormalities.)

Yes, there is left axis deviation (positive in I, negative in II), left atrial enlargement(> 1 x 1 boxes in V1) and LVH (R in V5 = 27 + S in V2 = 10 > 35 mm).

ALTERED IMPULSE

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ALTERED IMPULSECONDUCTION

1. Conduction blocks

(bradyarrhythmias)

2. Process of reentry(tachyarrhythmias )

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Bundle Branch Blocks

Turning our attention to bundle branch blocks

Remember normalimpulse conduction is

SA node AV node Bundle of His Bundle Branches Purkinje fibers

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Normal Impulse ConductionSinoatrial node

AV node

Bundle of His

Bundle Branches

Purkinje fibers

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Bundle Branch BlocksSo, depolarization ofthe Bundle Branchesand Purkinje fibers are

seen as the QRScomplex on the ECG.

Therefore, a conductionblock of the BundleBranches would bereflected as a change inthe QRS complex.

RightBBB

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Bundle Branch BlocksWith Bundle Branch Blocks you will see two changeson the ECG.

1. QRS complex widens (> 0.12 sec) .2. QRS morphology changes (varies depending on ECG lead,

and if it is a right vs. left bundle branch block) .

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Bundle Branch BlocksWhy does the QRS complex widen?

When the conduction

pathway is blocked itwill take longer forthe electrical signalto pass throughout

the ventricles.

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Right

BundleBranchBlocks

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Right Bundle Branch BlocksWhat QRS morphology is characteristic?

V1

For RBBB the wide QRS complex assumes aunique, virtually diagnostic shape in thoseleads overlying the right ventricle (V 1 and V 2).

Rabbit Ears

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Left BundleBranch

Blocks

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Left Bundle Branch BlocksWhat QRS morphology is characteristic?

For LBBB the wide QRS complex assumes acharacteristic change in shape in those leadsopposite the left ventricle (right ventricularleads - V 1 and V 2).

Broad,deep Swaves

Normal

3. Axis deviations:

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Right axis

Right axis

Left axis

Right axis

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Right axis

Left axis in frontal leads,and right axis in precordialleads

Asistol

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Arrhythmia Formation

Arrhythmias can arise from problems inthe:

Sinus node Atrial cells AV junction Ventricular cells

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SA Node Problems

The SA Node can: fire too slow fire too fast

Sinus BradycardiaSinus Tachycardia

Sinus Tachycardia may be an appropriateresponse to stress.

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Atrial Cell Problems

Atrial cells can: fire occasionally

from a focus

fire continuouslydue to a loopingre-entrant circuit

Premature AtrialContractions (PACs)

Atrial Flutter

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A re-entrantpathway occurs

when an impulseloops and resultsin self-

perpetuatingimpulseformation.

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Atrial Cell Problems

Atrial cells can also: fire continuously

from multiple fociorfire continuouslydue to multiplemicro re-entrantwavelets

Atrial Fibrillation

Atrial Fibrillation

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Multiple micro re-entrant waveletsrefers to wanderingsmall areas of

activation whichgenerate fine chaoticimpulses. Colliding

wavelets can, in turn,generate new foci ofactivation.

Atrial tissue

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AV Junctional Problems

The AV junction can: fire continuously

due to a loopingre-entrant circuit

block impulses

coming from theSA Node

Paroxysmal

SupraventricularTachycardia

AV Junctional Blocks

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Ventricular Cell Problems

Ventricular cells can: fire occasionally

from 1 or more foci fire continuously

from multiple foci

fire continuouslydue to a loopingre-entrant circuit

Premature Ventricular

Contractions (PVCs)Ventricular Fibrillation

Ventricular Tachycardia

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Arrhythmias

Sinus Rhythms Premature Beats Supraventricular Arrhythmias Ventricular Arrhythmias

AV Junctional Blocks

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Rhythm #1

30 bpm Rate? Regularity? regular

normal

0.10 s

P waves?

PR interval? 0.12 s QRS duration?

Interpretation? Sinus Bradycardia

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Sinus Bradycardia

Etiology: SA node is depolarizing slower

than normal, impulse is conductednormally (i.e. normal PR and QRSinterval).

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Rhythm #2


normal

0.08 s

P waves? PR interval?

0.16 s QRS duration?

Interpretation? Sinus Tachycardia

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Sinus Tachycardia

Deviation from NSR - Rate > 100 bpm

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Sinus Tachycardia

Etiology: SA node is depolarizing faster

than normal, impulse is conductednormally.

Remember: sinus tachycardia is a

response to physical or psychologicalstress, not a primary arrhythmia.

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Premature Beats

Premature Atrial Contractions (PACs)

Premature Ventricular Contractions (PVCs)

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Rhythm #3

70 bpm Rate? Regularity? occasionally irreg.

2/7 different contour

0.08 s


0.14 s (except 2/7) QRS duration?

Interpretation? NSR with Premature Atrial

Contractions

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Premature Atrial Contractions

Deviation from NSR These ectopic beats originate in the

atria (but not in the SA node),therefore the contour of the P wave,the PR interval, and the timing aredifferent than a normally generatedpulse from the SA node.

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Premature Atrial Contractions

Etiology: Excitation of an atrial cell

forms an impulse that is then conductednormally through the AV node andventricles.

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When an impulse originates anywhere inthe atria (SA node, atrial cells, AV node,

Bundle of His) and then is conductednormally through the ventricles, the QRSwill be narrow (0.04 - 0.12 s).

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Rhythm #4

60 bpm Rate? Regularity? occasionally irreg.

none for 7 th QRS

0.08 s (7th wide)



Interpretation? Sinus Rhythm with 1 PVC

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PVCs

Deviation from NSR Ectopic beats originate in the ventricles

resulting in wide and bizarre QRScomplexes.

When there are more than 1 prematurebeats and look alike, they are calleduniform. When they look different, they arecalled multiform.

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PVCs

Etiology: One or more ventricular cellsare depolarizing and the impulses areabnormally conducting through theventricles.

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When an impulse originates in aventricle, conduction through the

ventricles will be inefficient and the QRSwill be wide and bizarre.

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Ventricular Conduction

Normal Signal moves rapidlythrough the ventricles

Abnormal Signal moves slowlythrough the ventricles

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Supraventricular Arrhythmias

Atrial Fibrillation

Atrial Flutter Paroxysmal Supraventricular

Tachycardia

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Rhythm #5

100 bpm Rate? Regularity? irregularly irregular

none

0.06 s


none QRS duration?

Interpretation? Atrial Fibrillation

Atrial Fibrillation

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Atrial Fibrillation

Deviation from NSR No organized atrial depolarization, so

no normal P waves (impulses are notoriginating from the sinus node).

Atrial activity is chaotic (resulting in an

irregularly irregular rate). Common, affects 2-4%, up to 5-10% if

> 80 years old

Atrial Fibrillation

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Etiology: Recent theories suggest that itis due to multiple re-entrant wavelets

conducted between the R & L atria.Either way, impulses are formed in atotally unpredictable fashion. The AVnode allows some of the impulses topass through at variable intervals (sorhythm is irregularly irregular).

h h

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Rhythm #6


flutter waves

0.06 s


none QRS duration?

Interpretation? Atrial Flutter

l l

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Atrial Flutter

Deviation from NSR No P waves. Instead flutter waves (note

sawtooth pattern) are formed at a rateof 250 - 350 bpm.

Only some impulses conduct throughthe AV node (usually every otherimpulse).

A i l Fl

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Atrial Flutter

Etiology: Reentrant pathway in the right

atrium with every 2nd, 3rd or 4thimpulse generating a QRS (others areblocked in the AV node as the node

repolarizes).

Rh h #7

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Rhythm #7

74 148 bpm Rate? Regularity? Regular regular

Normal none

0.08 s


0.16 s none QRS duration?

Interpretation? Paroxysmal Supraventricular

Tachycardia (PSVT)

PSVT

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PSVT

Deviation from NSR The heart rate suddenly speeds up,

often triggered by a PAC (not seenhere) and the P waves are lost.

PSVT

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PSVT

Etiology: There are several types of

PSVT but all originate above theventricles (therefore the QRS is narrow).

Most common: abnormal conduction inthe AV node (reentrant circuit looping inthe AV node).

V i l A h h i

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Ventricular Arrhythmias


Ventricular Fibrillation

Rh h #8

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Rhythm #8


none

wide (> 0.12 sec)


none QRS duration?

Interpretation? Ventricular Tachycardia

V t i l T h di

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Deviation from NSR Impulse is originating in the ventricles

(no P waves, wide QRS).

V t i l T h di

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Etiology: There is a re-entrant pathway

looping in a ventricle (most commoncause).

Ventricular tachycardia can sometimes

generate enough cardiac output toproduce a pulse; at other times no pulsecan be felt.

Rh th #9

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Rhythm #9

none Rate? Regularity? irregularly irreg.

none

wide, if recognizable


none QRS duration?

Interpretation? Ventricular Fibrillation

V t i l Fib ill ti

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Deviation from NSR Completely abnormal.

V t i l Fib ill ti

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Etiology: The ventricular cells are

excitable and depolarizing randomly.

Rapid drop in cardiac output and death

occurs if not quickly reversed

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AV Nodal Blocks

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AV Nodal Blocks

1st Degree AV Block

2nd Degree AV Block, Type I 2nd Degree AV Block, Type II

3rd Degree AV Block

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BAV Gr. II, Mobitz II

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Rhythm #10

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Rhythm #10


normal

0.08 s



Interpretation? 1st Degree AV Block

Rhythm #11

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Rhythm #11

50 bpm Rate? Regularity? regularly irregular

nl, but 4th no QRS

0.08 s


lengthens QRS duration?

Interpretation? 2nd Degree AV Block, Type I

Rhythm #12

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Rhythm #12


nl, 2 of 3 no QRS

0.08 s

P waves? PR interval? 0.14 s QRS duration?

Interpretation? 2nd Degree AV Block, Type II

Rhythm #13

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Rhythm #13


no relation to QRS

wide (> 0.12 s)

P waves? PR interval? none QRS duration?

Interpretation? 3rd Degree AV Block

Remember

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Remember When an impulse originates in a ventricle,

conduction through the ventricles will beinefficient and the QRS will be wide and

bizarre.

IHD

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IHD

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ST Elevation Infarction

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ST Elevation InfarctionHeres a diagram depicting an evolving infarction: A. Normal ECG prior to MI

B. Ischemia from coronary artery occlusionresults in ST depression (not shown) andpeaked T-waves

C. Infarction from ongoing ischemia results inmarked ST elevation

D/E. Ongoing infarction with appearance ofpathologic Q-waves and T-wave inversion

F. Fibrosis (months later) with persistent Q-waves, but normal ST segment and T-waves

Non-ST Elevation Infarction

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Non-ST Elevation Infarction

ST depression & T-wave inversion

The ECG changes seen with a non-ST elevation infarction are:

Before injury Normal ECG

ST depression & T-wave inversion

ST returns to baseline, but T-waveinversion persists

Ischemia

Infarction

Fibrosis

Diagnosing a MI

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Diagnosing a MITo diagnose a myocardial infarction youneed to go beyond looking at a rhythmstrip and obtain a 12-Lead ECG.

RhythmStrip

12-LeadECG

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Anterior MI

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Anterior MI

Remember the anterior portion of the heart isbest viewed using leads V 1- V4.

Limb Leads Augmented Leads Precordial Leads

Lateral MI

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Lateral MISo what leads do you thinkthe lateral portion of theheart is best viewed?


Leads I, aVL, and V 5- V6

Inferior MI

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Inferior MINow how about theinferior portion of theheart?


Leads II, III and aVF

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What is the rate? Approx. 132 bpm (22 R waves x 6)

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A 16 yo young man ran into a guardrail while riding a motorcycle.In the ED he is comatose and dyspneic. This is his ECG.

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What is the rhythm? Sinus tachycardia

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What is the QRS axis? Right axis deviation (- in I, + in II)

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Is there evidence ofatrial enlargement?

No (no peaked, notched or negativelydeflected P waves)

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Is there evidence ofventricular hypertrophy?

No (no tall R waves in V1/V2 or V5/V6)

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Infarct: Are there abnormalQ waves?

Yes! In leads V1-V6 and I, avL

Any

Any

Any

20

30

30

30

3030

30

R40

R50

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Infarct: Is the ST elevationor depression?

Yes! Elevation in V2-V6, I and avL.Depression in II, III and avF.

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Infarct: Are there T wavechanges?

No

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lab 6-7 ecg 2014

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