Leads, Leads and
More Leads….
The question is..
where does this all “lead” us?
Silver Cross EMS Continuing Education
1st Trimester January 2013
By Laurie Carroll, RN, Adventist Bolingbrook Hospital
Silver Cross EMS Education Staff.
Our Agenda Today
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System announcements
Cardiac anatomy and physiology
EKG review (ALS)
12-lead review (ALS)
Mini-CME: Autism
Silver Cross EMSS announcements
• New 1st Quarter Region 7 QA – 12 lead use.
– Consider 12-leads for:
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Chest/arm/jaw/back pain (non-trauma)
Unexplained diaphoresis
Vomiting w/o fever or diarrhea
SOB/dizzy/syncope/weakness/fatigue
Epigastric pain (non-trauma)
Unexplained fall in elderly
Unexplained brady/tachy
– And document your decision to use/not use
Cardiac Anatomy Review
The Heart
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Four chambers
Hollow
Muscular
Dual Circulation
– feeds the heart muscle itself
– circulates blood outside the
heart
• lungs for oxygenation and
CO2 offload
• peripheral supply to
tissues, organs and organ
systems
Right Heart
• Receives unoxygenated
blood from
– systemic circulation
• vena cavae
– coronary circulation
• coronary sinus
• Blood passes from
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right atrium
through tricuspid valve
right ventricle
pulmonic valve
pulmonary artery
to lungs
Left Heart
• Receives oxygenated blood
from pulmonary vein
• Blood passes from
– left atrium
– mitral valve
– left ventricle
– aortic valve
– aorta
Aorta
• Oxygenated blood in the aortic
root enters the coronary
arteries
• Most myocardial blood supply
occurs during diastole
– the aortic valve leaflets are
closed and do not obstruct the
coronary artery roots
– the subendocardial blood vessels
are not compressed (as they are
during systole) allowing blood to
flow into the myocardium itself
– in the normal cardiac cycle,
diastole is longer than systole
Coronary Artery Disease
• Any narrowing of the
coronary arteries causes
– diminished blood supply
– restriction of delivery of
electrolytes and nutrients
Who Supplies What?
It is often helpful to understand
where the supply of blood is
coming from,
to help us understand which
areas of the heart are affected
by various strictures/occlusions.
LCA
• Left
– Left main divides into two
branches
– Left Anterior Descending (LAD)
• Anterior wall of LV
• RBB and portions of LBB
• Associated with Anterior Wall
MI
– Circumflex (Cx)
• Lateral and Posterior walls of
LV
• Left atrium
• SA node in ~ 30%
• Associated with Lateral Wall MI
RCA
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Right
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Right Atrium (RA)
Right Ventricle (RV)
Inferior and Posterior LV
SA node in ~60%
AV node
Associated with
right ventricular MI
or
dysrhythmias affecting
SA and AV nodes
Area of Injury
• Infarct =
dead or necrosis
• Blockage =
causes ischemia
Collateral Circulation
• If coronary artery disease and
stenosis develop slowly,
collateral circulation can
develop
• When the stenosis is acute,
collateral circulation does not
have time to develop
Cardiac Rhythm Disturbances
• CO (cardiac output) =
HR (heart rate) x SV (stroke volume)
• Rhythm disturbances can hamper delivery of blood
to the myocardium
Normal ECG Review
P wave
Smooth, rounded,
upright
P-R Interval
.12 - .20 seconds
QRS
Symmetrical
< .10 seconds
S-T Segment
Isoelectric
T wave
Upright, rounded
Hook ‘em up:
Where do the stickies go,
and why?
A lead is a record of electrical
activity between two electrodes.
Each lead records the average
current flow at a specific time in a
portion of the heart.
•Skin preparation:
dry, hair-free
•Placing the electrode. Be sure that
the electrode has adequate gel and
is not dry.
Trouble shooting EKG Clarity
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Equipment Grounded?
Cables attached?
Patient in reclining or semi fowler position?
Patient sitting still?
Skin clean and dry?
Limb leads in place or reversed?
There are three kinds of leads:
•Standard Limb Leads
•Augmented Leads
•Precordial Leads
Standard Limb Leads
(Remember: “lead” may refer to a direction, or placement.)
•Lead I: The positive lead is above the left breast or on the left arm and
the negative lead is on the right arm.
Records the difference of potential between the Left arm and Right arm.
•Lead II: The postive lead is on the left abdomen or left thigh and the
negative lead is also on the right arm.
Records the difference of potential between the left leg and the right arm.
•Lead III: The postive lead is also on the left abdomen or left lower
lateral leg but the negative lead is on the left arm.
Records the difference of potential between the left leg and the right arm.
Augmented Leads
•The four limb leads go on the four extremities as follows:
The upper extremities need placement of the electrodes
on the area of the lateral humoral aspect of the arms.
The lower extremities need placement of the electrodes
on the lateral lower legs near the lateral mallelous.
•Lead aVR faces the heart from the right shoulder and is
oriented to the cavity of the heart.
•Lead aVL faces the heart from the left shoulder and is oriented
to the Left Ventricle.
•Lead aVF face the heart from the left hip and is oriented to the
inferior surface of the Left Ventricle.
Precordial Lead Placement
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v1 - 4th ICS, R sternal border
v2 - 4th ICS, L sternal border
v3 - midway between v2 & v4
v4 - 5th ICS, L MCL
v5 - 5th ICS, between v4 & v6
v6 - 5th ICS, L mid-axillary line
Tip
Some find it easier to put
the leads on in this order v1, v2,
v4, v6
Then v3 and v5
You Lookin’ at Me?
It is important to look at
contiguous leads to determine
which area of the heart is
affected. Each lead is like a
camera lens that “looks” at an
area of the heart.
And how do I know if I have the leads in the
right place?
If everything in Lead I (P, QRS & T wave) is inverted, RA and RL are reversed.
Watch for the progression of the R wave in the precordial leads.
“R” WAVE PROGRESSION
•The right ventricle depolarizes faster
than the left ventricle because it is
smaller.
•The left ventricle sits to the left and
posterior to the right ventricle.
•As current spreads leftward through the
left ventricle, the height of the R wave in
the precordial leads progressively
increases.
•Normally, in V1 the R wave is more
negative and as it progress to V6 the R
wave becomes more positively deflected.
•“R” wave progression indicates that
current is flowing normally through the
anterior plane of the heart. (Conover)
ECG Patterns
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As contiguous leads look at different
parts of the heart, you may see an
ischemic pattern that covers a large
area or border area between two
regions.
– For example, if there is ST-segment
elevation in leads II/III/aVF/V5/V6, the
ischemia appears to be on both the
inferior and lateral areas, referred to
as inferolateral.
– Likewise, there are anterolateral and
anteroseptal (like the illustration here)
ischemic patterns.
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What is an ischemic pattern? The
AHA cites “typical ST-segment
elevation” as “> 1 mm in 2 or more
contiguous leads”
Injury=Elevated ST segment
•Signifies an acute process; ST returns to baseline with
time
•Location of injury can be determined in same
manner as infarct location
•Usually associated with reciprocal ST depression
in other leads
•If ST elevation is diffuse and unassociated
with Q waves or reciprocal ST depression,
consider pericarditis
Anterior MI
LAD
• Most lethal with highest mortality
• Can suddenly develop CHB, VF, VT
• If present with hemiblocks or BBB,
• Can extend to septum and/or lateral
walls
• Nitrates are desired over fluids
Anterior Infarction
Anterior Infarction
•ST elevation without abnormal Q
wave
•Usually associated with occlusion
of the left anterior descending
branch of the left coronary artery
(LCA)
Lateral or Septal
Wall MI
Rarely seen alone,
usually an extension of
anterior or inferior MI
Septal – Left Anterior Descending
Lateral – Left Circumflex
Pre Intervention
Post Intervention
Lateral Infarction
•ST elevation with/without abnormal Q wave.
•May be a component of a multiple-site
infarction
•Usually associated with obstruction of the left
circumflex artery.
Inferior Wall
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RCA
The most common type of MI
Nausea is common
Frequent re-infarction or extends to lateral wall
SA / AV node
SB, sinus arrest, HB - 1st or 2nd degree AV blocks, PVC’s
Nitrates if BP stable
Medical control may ask crew to hold nitro for inferior wall MI
until right sided infarct is ruled out.
Pre PCI
Post PCI
Inferior Infarction
•ST elevation with/without abnormal Q wave
Usually associated with right coronary artery
(RCA) occlusion
Right Ventricular MI
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Rare
RCA
LAD or Left circumflex could also cause
Right sided heart failure
Fluids – JVD with hypotension
Watch for inferior wall MI too!
Right Ventricular Infarction
•Usually accompanies inferior MI due to proximal
occlusion of the RCA
•Best diagnosed ST elevation in lead V4R
•An important cause of hypotension in inferior MI recognized by
jugular venous distension with clear lung fields
Aggressive therapy is indicated including:
reperfusion, adequate IV fluids for right heart filling, and
pacing to maintain A-V synchrony
Posterior Wall
• RCA
• Left Circumflex
• Seen with Inferior or lateral wall
Posterior Infarction
•Tall, broad (>0.04 sec) R wave and
ST depression in V1 and V2 (reciprocal changes)
•Frequently associated with inferior MI
•Usually associated with obstruction of
RCA and or left circumflex coronary artery
Reciprocal Changes
Region of ST
Elevation Region of ST Depression
Anterior (leads V1Inferior (true posterior)
V4)
Inferior (leads II, III, Anterior (leads V1-V3 or
aVF) lateral lead 1. aVL)
Lateral ( leads I, aVF,
V5, V6) Inferior ( leads II, III, aVF)
True Posterior
Anterior (leads V1-V3)
Making the accurate Field Diagnosis:
•There are elevations (1 mm) in
two contiguous or connecting leads:
(Leads adjacent to each other)
•There is at least one lead with reciprocal
changes..
Reminder:
•ECG would have changes in the area where the heart is being
affected.
• All other areas would look normal, without elevation or
depression unless there is an "old MI."
•In that case, the prior damage would show up as a depressed
segment.
Treat The Patient…
Not The Monitor
• If the patient’s symptoms do not match the
ECG, you need to do more detective work
• ECG is “nondiagnostic” in ~ 50% of patients
with chest discomfort
12 Lead
Review
#1
#1
Normal 12 Lead / #1
Acute Anterior Lateral Infarct/ #2
#2
#3
Anterolateral Infarct/ #3
#4
Acute Inferior Wall Infarct / #4
#5
Inferior Wall MI / Afib / #5
The EKG reveals an irregularly irregular rhythm
suggestive of atrial fibrillation. The rate is
variable, with a controlled or slow ventricular
response. The axis is physiologic. ST-T
changes suggestive of ischemia/injury are
present in leads II, III, and aVF. ST elevation of
>1mm in limb leads is indicative of a possible
inferior wall myocardial infarction. Reciprocal
changes are seen in leads one and aVL.
#6
Anterio-lateral / #6
A 55 year old man with 4 hours of “crushing” chest pain.
A 55 year old man with 4 hours of “crushing” chest pain.
Acute inferior myocardial infarction (with reciprocal changes)
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ST elevation in the inferior leads II, III and aVF
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reciprocal ST depression in the anterior leads
A 63 Year Old woman with 10 hours of chest
pain and sweating
Can you guess her diagnosis?
A 63 Year Old woman with 10 hours of chest pain and sweating
Can you guess her diagnosis?
Acute anterior-lateral myocardial infarction
ST elevation in the anterior leads V1 - 6, I and aVL
reciprocal ST depression in the inferior leads
Conduction Abnormalities
Bundle Branch Blocks
Right Bundle Branch Block
Right Bundle Branch Block
Pre PCI
Post PCI
Mini-CME: Autism
• Many patients we encounter in EMS have some form
of autism or fall somewhere on the autism spectrum
of disorders.
• This month, please register for and complete the
course Autism 101, found at: http://www.autismsociety.org/living-with-autism/how-we-canhelp/online-courses.html#autism101
• Submit the completion certificate to your EMS
coordinator (or Silver Cross EMSS Operations if you
are an independent provider).
•Thank you!
•Any further questions? If you are viewing the live
presentation, please feel free to type them in the
message box now.
•Otherwise, feel free to call or email the EMS
office or visit our website, ww.silvercrossems.com.