ppt

Julio Diaz NREMT-P TEMS

Training Officer

Gwinnett Fire Academy

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review the ECG waveform and intervals Define myocardial ischemia, injury and

infarction Identify the 5 major infarct areas on the

12 lead Name occluded arteries common to the

area Differentiate ECG changes reflecting

ischemia, injury and infarction Identify cardiac enzymes associated with

ACS

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A result of occlusion of arterial flow to the myocardium.

Ischemia, injury and necrosis is result Occlusion occurs via spasm, blood clot or

stenosis

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The Three I’s

Ischemialack of oxygenationST segment depression or T wave inversion

Injuryprolonged ischemiaST segment elevation

Infarctdeath of tissuemay or may not show a Q wave

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Injury/Infarct Recognition

Epicardial Coronary Artery

Lateral Wall of LV

Positive Electrode

Septum

Interior Wall of LV

Well Perfused Myocardium

Injury/Infarct Recognition

Normal ECG

Epicardial Coronary Artery

Lateral Wall of LVSeptum

Interior Wall of LV

Ischemia

Positive Electrode

Left Ventricular

Cavity

Ischemia◦ Inadequate oxygen to tissue◦ Represented by ST depression or T

inversion◦ May or may not result in infarct or Q

waves

ST Segment Depression

Thrombus

Ischemia

InjuryInjury

ST Segment Elevation

Infarcted AreaElectrically Silent

Depolarization

Infarct

Infarct◦ Death of tissue◦ Represented by Q wave◦ Not all infarcts develop Q waves

Inferior: II, III, AVFInferior: II, III, AVFSeptal: V1, V2Septal: V1, V2Anterior: V3, V4Anterior: V3, V4Lateral: I, AVL, V5, V6Lateral: I, AVL, V5, V6

I

II

III

aVR

aVL

aVF

V1

V2

V3

V4

V5

V6

I Lateral

II Inferior

III Inferior

aVR

aVL Lateral

V1 Septal

aVF Inferior

V2 Septal

V3 Anterior

V4 Anterior

V5 Lateral

V6 Lateral

Which coronary arteries are most likely associated with each group of

contiguous leads?

Left Main

Left Circumflex

Lateral Wall

Anterior Wall of Left Ventricle

Septal Wall

Right Ventricle

Right Coronary Artery

Anterior Descending Artery

Localization: Left Coronary Artery (LCA)

Left Main (proximal LCA) occlusion◦ Extensive Anterior injury

Left Circumflex (LCX) occlusion◦ Lateral injury

Left Anterior Descending (LAD) occlusion◦ Anteroseptal injury

Evidence in septal, anterior, and lateral leads

Often from proximal LCA lesion “Widow Maker” Complications common

◦ Left ventricular failure◦ CHF / Pulmonary Edema◦ Cardiogenic Shock

Proximal RCA occlusion◦ Right Ventricle injured◦ Posterior wall of left ventricle injured◦ Inferior wall of left ventricle injured

Posterior descending artery (PDA) occlusion◦ Inferior wall of right ventricle injured

Left Coronary Artery◦ Septal◦ Anterior◦ Lateral◦ Possibly Inferior

Right Coronary Artery◦ Inferior◦ Right Ventricular Infarct◦ Posterior

Hyperacute◦ Early change

suggestive of AMI◦ Tall & Peaked◦ May precede clinical

symptoms◦ Only seen in leads

looking at infarcting area

◦ Not used as a diagnostic finding

Evolution of AMI

Acute◦ ST segment elevation◦ Implies myocardial injury

occurring◦ Elevated ST segment

presumed acute rather than old

Age Undetermined◦ Wide (pathologic) Q

wave◦ No ST segment

elevation◦ Old or “age

undetermined” MI

A normal 12-lead ECG DOES NOT mean the patient is not having

acute ischemia, injury or infarction!!!

II, III, aVFII, III, aVF I, aVL, V leadsI, aVL, V leads

ST segment elevation is presumptive evidence for AMI

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12-Lead ECG AMI recognition

◦ Two things to know What to look for Where you are looking

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I and AVL

II, III and AVF

V3 & v4

V1 & v2

V5 & v6 Where the positive

electrode is positioned, determines what part of the heart is seen!

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Lead “Views”

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Limb Leads Chest Leads

I aVR V1 V4

II aVL V2 V5

III aVF V3 V6

Lead Groups

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T-wave inversion ( flipped T) ST segment depression T wave flattening Biphasic T-waves

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Baseline

ST segment elevation of greater than 1mm in at least 2 contiguous leads

Heightened or peaked T waves Directly related to portions of myocardium

rendered electrically inactive

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Baseline

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Inferior Wall

II, III, aVF◦ View from Left Leg ◦ inferior wall of left ventricle

I

II

III

aVR

aVL

aVF

V1

V2

V3

V4

V5

V6

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Lateral Wall I and aVL

◦ View from Left Arm ◦ lateral wall of left ventricle

I

II

III

aVR

aVL

aVF

V1

V2

V3

V4

V5

V6

Lateral Wall

V5 and V6◦ Left lateral chest◦ lateral wall of left ventricle

I

II

III

aVR

aVL

aVF

V1

V2

V3

V4

V5

V6

Lateral Wall

I, aVL, V5, V6◦ST elevation suspect lateral

wall injury

V3, V4◦ Left anterior chest◦ electrode on anterior

chest

I

II

III

aVR

aVL

aVF

V1

V2

V3

V4

V5

V6

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I

II

III

aVR

aVL

aVF

V1

V2

V3

V4

V5

V6

V3, V4◦ ST segment elevation

suspect anterior wall injury

Septal Wall V1, V2

◦ Along sternal borders◦ Look through right ventricle & see

septal wall

I

II

III

aVR

aVL

aVF

V1

V2

V3

V4

V5

V6

Septal

I

II

III

aVR

aVL

aVF

V1

V2

V3

V4

V5

V6

V1, V2◦ septum is left

ventricular tissue

RVI occurs around 40% in inferior MI’s

Significance◦ Larger area of infarct◦ Both ventricles ◦ Different treatment

Right leads “look” directly at Right Ventricle and can show ST elevations in leads II. III. AVF, V4R , V5R and V6R

Occlusion in RCA and proximal enough to involve the RV

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The single most accurate tool used in measuring RVI.

90% sensitive and specific

Posterior leads V1, V2◦Posterior Infarct with ST Depressions and/ tall R

wave ◦RCA and/or LCX Artery

Understand Reciprocal changes◦The posterior aspect of

the heart is viewed as a mirror image and therefore depressions versus elevations indicate MI

◦Rarely by itself usually in combo

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Anterior MI with lateral involvement

ST elevations V2, V3, V4

ST elevations II, AVL, V5

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Anteroseptal MI

ST elevations V1, V2, V3, V4

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Inferior MI

ST elevation 2,3 AVF

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Inferior lateral MI

ST elevations 2, 3, AVF

ST elevations V5

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•Acute inferior MI

•Lateral ischemia

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Normals◦ CPK- 10-155u/liter

begin rise 3-6 hours and peaks 12-24 with return to norm 3-5 days

◦ CPK-MB < than 5% IU/liter◦ LDH 85-200 IU/liter

Begin rise 12 hours, peaks 36-72 and normal around 10 days

◦ LDH 1- 18.1% - 29% of total◦ LDH 2- 27.4% to 37.5% of total

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Troponins- Now the Gold Standard!◦ Rises after 3-6 hours◦ Negative Troponin

within 6 hours of onset of S&S rules out the MI

◦ Peaks at about 20 hours

◦ May be raised for 14 days

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Troponin T◦ 84% sensitivity for MI 8 hours after onset of

symptoms◦ 22% for unstable angina

Advantages Highly sensitive for detecting myocardial ischemia Levels may help to stratify risks

Disadvantages Less specific than Troponin I Increased in angina Increased in chronic renal failure

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Troponin I◦ 90% sensitivity for MI 8 hours after onset of S&S

and 95% specificity◦ Level greater than 1.2 suggest MI◦ Negative rules out MI◦ Obtain two negative troponin values 4 hours

apart◦ Normally exceedingly low

◦Even a small elevation indicates myocardial damage

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Twelve Lead Electrocardiography for ACLS Providers, D. Bruce Foster, D.O.W.B. Saunders Company

Rapid Interpretation of EKG’s , Dale Dubin, M.D., Cover Publishing Co. 1998

ECG’s Made Easy, Barbara Aehlert, RN, Mosby, 1995 The 12 Lead ECG in Acute Myocardial Infarction, Tim Phalen,

Mosby, 1996 Color Coding EKG’s , Tim Carrick, RN, H &H Publishing, 1994 www.ecglibrary.com/ecghome.html www.urbanhealth.udmercy.edu/ekg/read.html www.ecglibrary.com/ecghome.html www.nyerrn.com/h/ekg.htm

Drawings by Jill Gregory, Medical Illustrator, CGEY

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