ONTARIO
BASE HOSPITAL GROUP
Chapter 6
for 12 Lead Training
-Introduction to 12 Lead InterpretationOntario Base Hospital Group
Education Subcommittee
2008
TIME IS
MUSCLE
Introduction to 12 Lead
Interpretation
AUTHOR
REVIEWERS/CONTRIBUTORS
Greg Soto, BEd, BA, ACP
Neil Freckleton, AEMCA, ACP
Hamilton Base Hospital
Niagara Base Hospital
Jim Scott, AEMCA, PCP
Sault Area Hospital
Ed Ouston, AEMCA, ACP
Ottawa Base Hospital
Laura McCleary, AEMCA, ACP
SOCPC
Tim Dodd, AEMCA, ACP
Hamilton Base Hospital
2008 Ontario Base Hospital Group
Dr. Rick Verbeek, Medical Director
SOCPC
OBHG Education Subcommittee
Chapter 6 - Objectives
 Recognize
the usefulness of ECG data provided
by computerized 12 Lead ECG
 Identify important features of ECG such as Q, R,
S, T waves and relate to 12 Lead interpretation
 Find J-points and compare to TP segments
 Recognize ST-elevation and relate to clinical
significance
 Become comfortable with recognizing and
locating AMI on 12 Lead ECG
 Practice a bit of 12 Lead interpretation
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12 Lead Interpretation
Interpretation
vs. STEMI Recognition
 It is important to note that upon
completion of this training, it is not
expected that paramedics will be
“interpreting” a 12 Lead but rather
recognizing STEMI patients
OBHG Education Subcommittee
Learning 12 Lead ECG
Interpretation
Common Paramedic responses prior to
learning 12 Lead ECG Interpretation:
 I can’t interpret a 12 Lead ECG like a
Cardiologist!
 Are you kidding me?
Common Paramedic responses after learning
12 Lead ECG Interpretation:
 Hey – that wasn’t as hard as I thought it
would be!
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Essential Interpretation
Goals
 Recognize
and localize
AMI on the ECG
 Feel comfortable with 12
Lead interpretation
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12 Lead ECG
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12 Lead ECG
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12 Lead ECG
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R Wave
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Q Wave
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S Wave
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J-Point
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ST Segment
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The J Point
J
point - end of QRS complex &
beginning of ST segment
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Practice
 Find
J-points and ST segments
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Practice
 Find
J-points and ST segments
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12-Lead ECG
AMI
recognition
 Two
things to know
 What
to look for
 Where to look
Local medical oversight will determine the criteria used
to identify a STEMI patient. All stakeholders must be
consulted to determine what criteria should be utilized
in a given centre.
OBHG Education Subcommittee
What to look for
Example
- ST segment elevation
 One
millimetre or more (one small
box) in limb leads
 Two millimetres or more (two small
boxes) in chest leads
 Present in two anatomically
contiguous leads
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Contiguous Leads
 Limb
leads that “look” at the same area
of the heart
OR
 Numerically
consecutive chest leads
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Contiguous Leads
 Inferior
wall: II, III, avF
 Lateral wall: I, aVL, V5, V6
 Septum: V1 and V2
 Anterior wall: V3 and V4
 Posterior
wall: V7, V8, V9
(leads placed on the patient’s back 5th
intercostal space creating a 15 lead EKG)
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Where to look
 ST

segment elevation measurement
0.04 seconds after J point
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ST Segment Elevation
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ST Segment Elevation
Presumptive
evidence
of AMI
Indication
for acute
reperfusion therapy
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ST Segment
 Compare
to TP segment
ST
TP
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ST Segment Analysis
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Practice
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Lead “Views”
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Lead Groups
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
Limb Leads
Chest Leads
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Lead “Views”
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Inferior Wall
 II,

III, aVF
Left Leg
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
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Inferior Wall
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
Inferior Wall
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Lateral Wall
I
and aVL
 Left
Arm
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
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Lateral Wall
 V5

and V6
Left lateral chest
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
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Lateral
 I,
aVL, V5, V6
Lateral Wall
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
OBHG Education Subcommittee
Anterior Wall
 V3,

V4
Left anterior chest
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
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Anterior Wall
• V3, V4
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
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Septal Wall
V1,
V2
Along sternal borders
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
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Septal
• V1,V2
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
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AMI Localization
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
Anterior:
Septal:
Inferior:
Lateral:
V3, V4
V1, V2
II, III, AVF
I, AVL, V5, V6
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AMI Recognition
I Lateral
aVR
II Inferior
aVL Lateral
III Inferior
aVF Inferior
V1 Septal
V4 Anterior
V2 Septal
V5 Lateral
V3 Anterior
V6 Lateral
OBHG Education Subcommittee
AMI Recognition
 Know
what to look for

ST elevation

> 1mm in limb leads

> 2mm chest leads

Two contiguous leads
 Know

where you are looking
You will soon have this memorized
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Mnemonic for Location
 Rhyme,
phrase or device for remembering
something
 “LII – LI – ASS (backwards) – ALL”
L = I (Lateral)
I = II (Inferior)
I = III (Inferior)
L = aVL (Lateral)
I = aVF (Inferior)
S = V1 (Septal)
S = V2 (Septal)
A = V3 (Anterior)
A = V4 (Anterior)
L = V5 (Lateral)
L = V6 (Lateral)
OBHG Education Subcommittee
Using mnemonic on ECG
 You
may want to write the Letters in the
corner of each Lead when interpreting
L
S
A
I
L
S
L
I
I
A
L
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Antero Septal
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Extensive Anterior
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Inferior
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Extensive Anterior
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Inferior
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Extensive Anterior
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Normal ECG
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Inferior
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Infero-lateral
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Inferior
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Inverted T-waves = ischemia
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ONTARIO
BASE HOSPITAL GROUP
QUESTIONS?
ONTARIO
BASE HOSPITAL GROUP
Well Done!
Education Subcommittee
START
QUIT