A 12-lead electrocardiogram (ECG) provides crucial information regarding the heart's electrical system and is commonly used for diagnosing acute coronary syndromes and dysrhythmias. Proper lead placement, preparation of the skin, and the patient's positioning are essential for accurate readings, along with immediate reporting of critical values observed in the ECG. The document highlights guidelines for conducting a 12-lead ECG, including electrode placement and maintenance, as well as the significance of timely and precise recording for patient care.

1. By: Ahmad Amirdash, BSN, CCRN
Clinical Resource Nurse, EC

2. *A 12-lead electrocardiogram (ECG) provides
information about the electrical system of
the heart from 12 different views, or leads.
Common uses of a 12-lead ECG include
diagnosis of acute coronary syndromes,
identification of dysrhythmias, and
determination of the effects of medications
or electrolytes on the electrical system of the
heart.
*There are SIX chest ( precordial ) leads &
FOUR limb leads.

3. *Check cables and lead wires for fraying, broken
wires or discoloration before placement.
*It may be necessary to clip chest hair to ensure
good skin contact with the electrode.
*Respiratory artifact can be common in doing the
chest leads and may require position changes to
ensure a good baseline. If sequential (serial) ECGs
are to be obtained, chest lead sites should be
marked to ensure that the same lead sites are used
in subsequent ECGs. Some pregelled electrodes
can be left in place for repeat ECGs.

4. *The supine position is best, but Fowler or other
positions may be used for comfort. ECGs should be
recorded in the same position each time to ensure
that tracing changes are not caused by changes in
body position. If another position is clinically
required, note the position on the tracing or in the
comments of the LCD input. Do not compromise
lead placement because of a medication patch.
Relocate the medication patch before applying the
leads.
*Expose only the necessary parts of the patients
legs, arms, and chest. This Provides privacy and
warmth, which reduces anxiety, shivering and
resulting artifacts.

5. *Clean the intended sites with alcohol pads,
cleansing pads or soap and water, and dry
thoroughly since moist skin is not conducive to
electrode adherence.
*When applying the electrodes they must be secure
to prevent external influences from affecting the
ECG. The pregelled electrodes must be moist and
adhesive to allow for appropriate conduction of
impulses.
*Ensure that the patient is in the supine position, not
touching the bedrails or footboard which may
increase the chance of distortion of the trace.

6. *The following are the critical values that
require reporting ( depends on your
institution)
1- VT/VF
2- ST elevation, injury pattern
3- High degree AVB ( AV dissociation, 2:1
AV block, 3rd degree block )
4- Severe bradycardia ( HR < 40 bpm )

7. *You can perform an ECG stat in
Extremely Urgent situations.
However, All ECGS need to have:
date of birth, tech initial ASAP
afterwards. You also need to hold
off transmitting the tracing until all
information is complete. So please
make sure you enter this info as
soon as you get it.

8. **NOTE: The leads are listed out of numerical
order, intentionally because it facilitates easier
lead placement.
*Identify the angle of Louis or the sternal notch.
This assists with identifying the second rib for
correct placement of precordial leads in the
appropriate intercostal space ( ICS ).
*Slight alterations in the position of any of the
precordial leads may alter the ECG significantly
and can have impact on diagnosis and treatment.

9.  V1 :
*Palpate the upper sternum to identify where the
clavicle joins the sternum (suprasternal notch).
Slide fingers down the center of the sternum to
the obvious bony prominence. This is the sternal
notch, or angle of Louis which serves as your
landmark. Move directly to the Right(of the
patient ) and you will feel a gap. That gap is the
second intercostal space. Slide your fingers
down over the rib until you feel the next gap.
This is the third intercostal space. Move down
over one more rib and into the next gap, the
fourth intercostal space.
This is where V1 is to be placed.

10.  V2 :
*Lead V2 is to placed directly across from V1 in
the fourth ICS, on the left side of the sternum.
 V4 :
*Lead V4 is placed in the 5th intercostal space,
midclavicular.
 V3 :
*Lead V3 is placed directly horizontally &
equidistant in between Leads V2 and V4.

11. V6 :
*Lead V6 is placed in the 5th intercostal
space, midaxillary horizontally level with V4 .
V5 :
*Lead V5 is placed horizontally & equidistant in
between leads V4 and V6 (anterior axillary line )
 please see the following illustration

12. Diagram showing the correct placement for a 12-LEAD ECG.
Source: University of Nottingham

13.  Limb leads should be placed in fleshy areas, and
bony prominences should be avoided. The limb
leads should be positioned in approximately the
same place on each limb.
*Note : I have noticed the technicians in the
Cardiopulmonary Care Center place the lower limb
leads on the lower abdomen.
*please see the following illustration

14. Limb lead placement in 12-lead ECG
Source : Mosby’s Nursing procedures & skills

15. *The ECG must be marked accurately and have a
clear baseline without artifact for correct
interpretation. Three to six seconds are all that are
needed for a permanent record; a longer strip may
be obtained if a rhythm strip is needed. A rhythm
strip is a long recording of a lead; lead II is
commonly used.
*When connecting the wires to the Leads please
double check the right wire to the matching lead.
You will notice that the sequence is :
RA, V1, V2, V3, V4, V5, V6, LA on one side &
RL, LL on the other side.

16. *If you forget any of the steps or the sequence, a
quick reference with 2 diagrams is printed on
the ECG machine surface (most machines). In
summary, you will enter the patient information
first, then place the leads, connect them, then
record a trace.
*Remember to plug the ECG machine after use
please.
*Anyone in the health field setting can learn how
to do a 12-Lead ECG. It just takes practice.

17. *Here is a link for a short video ( 4
minutes 25 sec. ) that demonstrates
the whole procedure. Copy this link &
paste it in your window please.
http://elscontent.webinservice.com/NursingSkills
/Animations/CC_057/AnimationPlayer.html

18. *ECG stands for Electrocardiogram, which originally
came from the German word elektrokardiogramm.
*this is where the acronym EKG comes from. The
German elektrisch means “electrical,” kardio means
“heart,” and the Hungarian gramm means “measure
of mass.” The two acronyms ECG and EKG are used
interchangeably; however, ECG tends to sound like
another common medical acronym, EEG, or
Electroencephalogram. For this reason some medical
professionals prefer to say EKG.
*-LEAD EKGs are similar to standard EKGs ( monitor )
except that they are more accurate & look at the
heart through more angles.

19. *According to recent estimates by the American Heart
Coronary heart disease caused approximately 1 of every
6 deaths in the United States in 2006. Coronary heart
disease mortality in 2006 was 425 425. In 2010, an
estimated 785 000 Americans will have a new coronary
attack, and approximately 470 000 will have a recurrent
attack. It is estimated that an additional 195 000 silent
first myocardial infarctions occur each year.
Approximately every 25 seconds, an American will have
a coronary event, and approximately every minute,
someone will die of one. Prehospital 12-LEAD EKGs are
allowing patients to reach definitive care immediately
upon arrival at their local emergency department.

20. * Jacobson, C. (1996). Bedside cardiac monitoring. In: AACN Research
Based Practice Protocol, Technology Series. Aliso Viejo, CA:
American Association of Critical Care Publications, 1-32.
* Drew, B.J. (2002). Celebrating the 100th birthday of the
electrocardiogram: Lessons learned from research in cardiac
monitoring. Am J Crit Care, 11, 378-86.
* Circulation 2010, 121:e46-e215: Heart Disease and Stroke Statistics-
-2010 Update : A Report From the American Heart Association
originally published online December 17, 2009.
* Excerpted and adapted from AACN Procedure Manual for Critical
Care, Fifth Edition, American Association of Critical-Care Nurses,
edited by Debra J. Lynn-McHale Wiegand, PhD, RN, CCRN, FAAN,
and Karen K. Carlson, MN, RN, CCNS, St. Louis: Elsevier/Saunders,
2005.

22. Ahmad Amirdash BBA, BSN, CCRN
Clinical Resource Nurse
Emergency center, M.D Anderson Cancer Center
1515 Holcombe Blvd, Houston TX 77030
aamirdash@mdanderson.org
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