12 Lead Essential
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Transcript of 12 Lead Essential
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Topics
q Anatomy Revisitedq The 12 Lead ECG Deviceq
The 12 Lead ECG Formatq Waveform Componentsq Lead Views
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Anatomy Revisitedq RCA
right ventricle inferior wall of LV posterior wall of LV (75%) SA Node (60%) AV Node (>80%)
q LCA septal wall of LV anterior wall of LV
lateral wall of LV posterior wall of LV (10%)
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Anatomy Revisitedq SA nodeq Intra-atrial pathwaysq AV nodeq
Bundle of Hisq Left and Right bundle
branches left anterior fascicle left posterior fascicle
q Purkinje fibers
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The 12 Lead ECG Device
q Device serves as a voltmeter measures the flow of electricity
q Unipolar vs Bipolar Leads
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Bipolar Leadsq 1 positive and 1 negative
electrode RA always negative LL always positive
q Traditional limb leads areexamples of these Lead I Lead II Lead III
q View from a vertical plane
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Unipolar Leadsq 1 positive electrode & 1
negative reference point calculated by using summation
of 2 negative leadsq Augmented Limb Leads
aVR, aVF, aVL view from a vertical plane
q Precordial or Chest Leads V1-V6 view from a horizontal plane
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The 12-Lead ECG FormatLeads typicallyproduced bydevices usedprehospital
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The 12-Lead ECG Format
Fields nottypicallyproduced bydevices usedprehospital
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The 12-Lead ECG Format
Device prints out 2.5 seceach of Leads I, II, IIIthen switches to aVR,aVL, aVF then switches
to V1, V2, V3 and then toV4, V5, V6 (varies bydevice)
Device computer
analyzes all 10 sec of all12 leads but only prints2.5 sec of each group
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The 12-Lead ECG FormatT h
e c om
p u t er
d i a
gn
o si si s
n o t al w
a y s a c c ur a
t e! ! !
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The 12-lead ECG Format
The computer IS veryaccurate atmeasuringintervals &durations
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Waveform Components:
R WaveFirst positive deflection; Rwave includes thedownstroke returning to
the baseline
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Waveform Components:Q Wave
First negative deflectionbefore R wave; Q wave
includes the negativedownstroke & return tobaseline
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Waveform Components:S Wave
Negative deflectionfollowing the R wave; Swave includes departurefrom & return to baseline
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Waveform Components:QRS
q Q waves Can occur normally in several leads
Normal Q waves called physiologic
Physiologic Q waves < .04 sec (40ms)
Pathologic Q
>.04 sec (40 ms)
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Waveform Components:QRS
q Q wave Measure width
Pathologic if greater than or equal to 0.04 seconds(1 small box)
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Waveform Components:QS Complex
Entire complex isnegatively deflected;No R wave present
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Waveform Components:J-Point
Junction between end of QRS andbeginning of ST segment; WhereQRS stops & makes a sudden
sharp change of direction
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Waveform Components:ST Segment
Segment between J-pointand beginning of T wave
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Waveform Components:ST Segment
q Need reference point Compare to TP segment DO NOT use PR segment as reference!
ST TP
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Waveform Components:Practice
q Find J-points and ST segments
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Waveform Components:Practice
q Find J-points and ST segments
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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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Inferior Wall
q 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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Inferior Wall
Inferior Wall
I
II
III
aVR
aVL
aVF
V1
V2
V3
V4
V5
V6
q Posterior View portion resting on diaphragm ST elevation suspect
inferior injury
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Lateral Wall
q I and aVL View from Left Arm
lateral wall of left ventricle
I
II
III
aVR
aVL
aVF
V1
V2
V3
V4
V5
V6
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Lateral Wall
q V5 and V6 Left lateral chest lateral wall of left ventricle
I
II
III
aVR
aVL
aVF
V1
V2
V3
V4
V5
V6
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Lateral Wall
Lateral Wall
q I, aVL, V5, V6 ST elevation suspect
lateral wall injury
I
II
III
aVR
aVL
aVF
V1
V2
V3
V4
V5
V6
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Anterior Wall
q 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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Anterior Wall
I
II
III
aVR
aVL
aVF
V1
V2
V3
V4
V5
V6
q V3, V4 ST segment elevation
suspect anterior wallinjury
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Septal Wallq V1, V2
Along sternal borders Look through right ventricle & see
septal wall
I
II
III
aVR
aVL
aVF
V1
V2
V3
V4
V5
V6
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Septal
I
II
III
aVR
aVL
aVF
V1
V2
V3
V4
V5
V6
q V1, V2 septum is left
ventricular tissue
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ST Segment Analysis
For each complex, determine whether the ST segment iselevated one millimeter or more above the TP segment
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12-Lead ECG
q AMI recognition Two things to know
What to look for Where you are looking
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AMI Recognition
q What to look for ST segment elevation
One millimeter or more (one small box) Present in two anatomically contiguous
leads