12-Lead ECG and STEMI Basics

12-Lead ECG and
STEMI Basics

Disclosure Statement
• Tom Bouthillet, NREMT-P
• Captain, Town of Hilton Head Island,
South Carolina, Fire & Rescue Division
• 12-Lead ECG and STEMI Basics
• Speakers Bureau, Physio-Control
• No off-label drug uses
• No relevant financial relationships to
disclose

Time is therapy for
STEMI patients!

N Engl J Med 2007;357:1631-1638
Significant increase in mortality for
every 15 minutes of delay!

Who should get a
12-lead ECG?

All of these complaints warrant a
12-lead ECG!
• Chest pain
• Atypical chest pain
• Epigastric pain
• Back, neck, jaw, or arm pain without chest pain
• Palpitations
• Syncope or near syncope
• Pulmonary edema
• Exertional dyspnea
• Weakness
• Diaphoresis unexplained by ambient temperature
• Feeling of anxiety or impending doom
• Suspected diabetic ketoacidosis

What about cardiac arrest
patients with ROSC?
• Also include patients who are
successfully resuscitated from cardiac
arrest!

This patient was observed to collapse from sudden cardiac arrest. The
initial rhythm was ventricular fibrillation. After 2 shocks and minimally
interrupted chest compressions the patient experienced return of
spontaneous circulation (ROSC)

The post-arrest 12-lead ECG showed acute inferior STEMI. It was
immediately transmitted to the hospital.

How about flu-like symptoms?

For example
• A 66 year old female complains of nausea
and vomiting
• She’s certain that she has the flu!
• When questioned, she admits to having
mild chest discomfort on and off for the
last 2 days

The 3-lead ECG looks good…

The 12-lead ECG can wait until
the patient is loaded in the back
of the ambulance!

Right?

Wrong!

The old concept
“Put the patient on
the monitor.”

The new concept
“Obtain a 12-lead
ECG!”

When?
• With the first set of vital signs and before
oxygen and nitroglycerin (unless the
patient is in respiratory distress or the
room air SpO2 < 94)
• Ideally, the 12-lead ECG should be
captured within 10 minutes of making
patient contact (the “at patient” time)

Where?
• On the scene, prior to relocating the
patient to the ambulance (unless it is
absolutely necessary to protect the
patient’s dignity)

How?
• Whenever possible undress patients from
the waist-up!
• For female patients, this can include the
bra but protect the patient’s modesty and
dignity
• Alert and cooperative patients can remove
their own bra if you hold up a towel or
sheet to give them some privacy
• It’s easier to place electrodes and it’s the
only way to perform a physical exam!

How?
• The proper way to move a patient’s breast
out of the way is with the back of a gloved
hand
• You can also have patients lift up their
own breast
• Tip: Obtain gowns from the emergency
department so that patients can be
covered up after the electrodes are placed

Skin Prep
• The chest hair should be removed with the
electric clippers if possible
• If the patient is diaphoretic, wipe off the
skin!
• Benzoin tincture works great! But it’s also
flammable so don’t defibrillate over it.

Lead Placement
• The limb leads go on the limbs
• The white and black electrodes can be
placed on the center of the muscle
mass of the deltoids (which leaves room
for the BP cuff)
• The red and green electrodes can be
placed on the quadriceps (or a nonbony
and non-hairy part of the leg)

RA
LA
RA = Right Arm
LA = Left Arm
RL = Right Leg
LL = Left Leg
RA
LA
RL
LL
RL
LL
RA - White
LA - Black
RL - Green
LL - Red

Lead Placement
• When placing the precordial leads, keep
the edges of the electrodes lined up! It will
help keep you organized!

V6
V5
V1
V2
V3
V4

Common Mistakes
• The limb leads are placed on the chest!
• Leads V1 and V2 are placed one or two
intercostal space too high on the chest (or
even higher)
• Leads V1 and V2 are placed too far apart
(if you make a “peace sign” you should be
able to touch both electrodes)
• Lead V3 is placed directly beneath lead V2
• Lead V4 is under the nipple instead of the
midclavicular line

Tips for achieving excellent
data quality
• Strand each lead out individually!
• When the ECG leads are wrapped around
each other, or wrapped around the IV line,
the O2 tubing, or the BP tubing, it can
increase artifact!
• Make sure the patient isn’t “twiddling” the
leads

Tips for achieving excellent
data quality
• Make sure the patient is resting in a semi-
Fowler’s position and breathing normally
• The patient should not be propping him or
herself up with his or her arms
• This can be transmitted into the 12-lead
ECG is muscle tremor artifact

Tips for achieving excellent
data quality
• If the patient is shivering, lay a sheet,
towel, or blanket over the patient prior to
capturing the 12-lead ECG
• This can also help minimize
Parkinsonian muscle tremors

This 12-lead ECG was obtained from a firefighter during
training at the fire station. It was cold at the station (they don’t
call it the “Ice House” for nothing) and you can see muscle
tremor artifact in the ECG.

The second 12-lead ECG was captured after placing a single
towel over the firefighter. What a difference!

Tips for achieving excellent
data quality
• For some patients, it’s very difficult to get a
clean tracing (e.g., acute respiratory
distress, very diaphoretic patients)
• However, in most cases it’s possible to
obtain a 12-lead ECG with excellent, or at
least acceptable data quality
• It takes the desire to obtain a clean 12-
lead ECG and the knowledge to
troubleshoot problems

Okay, I’ve got my 12-lead ECG…

Now what?

Sample STEMI Alert Protocol
• Hilton Head Island Fire & Rescue
• This protocol does an excellent job
identifying patients with acute STEMI
• All protocols must have buy-in from the
stakeholders in the system of care!
• “If you’ve seen one EMS system, you’ve
seen one EMS system”
• There is more than one way to do this!

Patient has signs and symptoms of ACS
12 lead ECG shows excellent data quality
Computer reads ***ACUTE MI SUSPECTED***
QRS duration is < 120 ms (0.12 s)
Paramedic agrees with computer interpretation
ECG shows 1 mm of ST-segment elevation in 2 or
more contiguous leads (2 mm in leads V2 or V3)
Reciprocal changes are present
Contact dispatch and announce “STEMI Alert”
Transmit the ECG to the emergency department

Step 1
• Is the patient showing signs and symptoms
of an acute coronary syndrome (ACS)?
• This is usually (but not always) chest pain
• If yes, then move on to Step 2

Step 2
• Have I obtained a 12-lead ECG with
excellent data quality?
• This is an extremely important step!
• Poor data quality confounds computer
measurements and causes interpretive
algorithm to give inaccurate readings!
• Poor data quality makes subtle
interpretation of ST-segments difficult or
sometimes impossible

Step 2
• If you’re having trouble obtaining a high
quality 12-lead ECG, stop and correct the
problem!
• Don’t just say, “We’ve got to go!”
• Troubleshooting the problem is time well
spent!
• I have seen reperfusion delayed because
of poor data quality
• I have seen patients cathed because of
poor data quality!

Here poor data quality is triggering the ***ACUTE MI SUSPECTED***
message. This message has a high specificity for acute STEMI, but only
when the patient has signs and symptoms of ACS and the data quality is
excellent! The STEMI Alert should not be called from the field based on
this 12-lead ECG.

Here the data quality is good, but flutter waves are triggering the
***ACUTE MI SUSPECTED*** message. A STEMI Alert should not be
called from the field. Note: False positive messages are more common
with tachycardias.

Here the data quality is good, but it’s a wide complex tachycardia (paced
rhythm as evidenced by pacer spikes in leads V4, V5, and V6). This ECG
was captured on an interfacility transport. The patient was unconscious
and intubated, en route to neurosurgery. Question: Were “signs and
symptoms of ACS” present?

Step 3
• Either the computerized interpretation
reads ***ACUTE MI SUSPECTED *** and
the paramedic agrees with the
computerized interpretation….
• Or the QRS duration is < 0.12 s, STsegment
elevation is present in 2 or more
contiguous leads, and reciprocal changes
are present

Patient has signs and symptoms of ACS
12 lead ECG shows excellent data quality
Computer reads ***ACUTE MI SUSPECTED***
QRS duration is < 120 ms (0.12 s)
Paramedic agrees with computer interpretation
ECG shows 1 mm of ST-segment elevation in 2 or
more contiguous leads (2 mm in leads V2 or V3)
Reciprocal changes are present
Contact dispatch and announce “STEMI Alert”
Transmit the ECG to the emergency department

In this example the interpretive algorithm is giving the ***ACUTE MI
SUSPECTED*** message but the ECG is showing no signs of acute injury.
The STEMI Alert should not be called from the field. Note: The inverted P-
waves in the inferior leads artificially depressed the baseline which made the
computer think the ST-segments were elevated.

In this example, the 12-lead ECG shows an obvious STEMI, but for some
reason the data quality prohibits a computerized interpretation and no
reciprocal changes are present. What should you do?

Answer: Correct the problem and obtain an additional 12-lead ECG. Now
the data quality is acceptable, the interpretive algorithm says ***ACUTE
MI SUSPECTED*** and the paramedic agrees with the computerized
interpretation. This is the ECG that should be transmitted to the
emergency department.

For this borderline case found on the LIFENET it is questionable as to
whether or not 2 mm of ST-segment elevation are present in leads V2
and V3. However, reciprocal changes appear to be present in leads III
and aVF. What should the treating paramedic do?

Answer: Perform serial ECGs! Less than 5 minutes later, this evolving STEMI
triggers the ***ACUTE MI SUSPECTED*** message.

In this example, the interpretive algorithm isn’t giving the ***ACUTE MI
SUSPECTED*** message even though hyperacute T-waves are evident in
leads V2 and V3 and reciprocal changes are present in leads III and aVF.
Remember, it’s just a computer! It doesn’t know when to ignore the rules. So
what should the treating paramedic do?

Answer: Either call the STEMI Alert based on the hyperacute T-waves and
reciprocal changes or perform serial ECGs! Less than 5 minutes later the
interpretive algorithm is giving the ***ACUTE MI SUSPECTED*** message.

The vast majority of the time,
calling a Code STEMI should
be a simple decision!

Interpretive statement says ***ACUTE MI SUSPECTED***
Reciprocal changes
ST-segment elevation suggestive of
acute injury

STEMI Recognition
• Check out the free webinar “STEMI
Recognition: Beyond the Basics” online
at EMS World

Normal ECG

V6
V5
V4
V1
V2
V3

V9
V8
V7
V6
V5
V4R
V4
V1
V2
V3

What is a Reciprocal Change?

II
I

Upwardly Concave
Upwardly Convex
(or “straight” or “non-concave”)

Inferior STEMI

Inferior STEMI

Inferior STEMI

Inferior STEMI

HR 68
PR 188
QRS 104
P-R-T 84 84 106

V6
V4R
V1
V2
V3
V5

HR 65
PR 190
QRS 102
P-R-T 84 76 107 V4R

HR 80
PR 204
QRS 113
P-R-T 69 84 111

Anterior STEMI

Anterior STEMI

Anterior STEMI

Anterior STEMI

Lateral STEMI

Lateral STEMI

Lateral STEMI

Lateral STEMI

Posterior STEMI

Posterior STEMI

BMJ 2002; 324:831-834

Posterior STEMI

Posterior STEMI

Posterior STEMI

Tom Bouthillet
• Email: ems12lead@gmail.com
• Phone: 843-247-3453 (cell)
• Website: ems12lead.com
• Facebook: facebook.com/ems12lead
• Twitter: @tbouthillet / @EMS12Lead