Common ECG Lead Placement Errors. Part II: Precordial Misplacements

Abstract

Background: Electrocardiography is a very useful diagnostic tool. However, errors in placement of ECG leads can create artifacts, mimic pathologies, and hinder proper ECG interpretation. This is the second of a two-part series discussing how to recognize and avoid these errors.

Methods: 12-lead ECGs were recorded in a single male healthy subject in his mid 20s. Various precordial lead misplacements were compared to ECG recordings from correct lead placement.

Results: Precordial misplacements caused classical changes in ECG patterns. Techniques of differentiating these ECG patterns from true pathological findings were described.

Conclusion: As in Part I of this series, recognition and interpretation of common ECG placement errors is critical in providing optimal patient care.

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Common ECG lead placement errors. Part II: Precordial
Misplacements
Allison V. Rosen,1 Sahil Koppikar,2 Catherine Shaw,3 Adrian Baranchuk.3
Abstract
Background: Electrocardiography is a very useful diagnostic tool. However, errors in placement of ECG leads can create artifacts, mimic
pathologies, and hinder proper ECG interpretation. This is the second of a two-part series discussing how to recognize and avoid these
errors. Methods: 12-lead ECGs were recorded in a single male healthy subject in his mid 20s. Various precordial lead misplacements were
compared to ECG recordings from correct lead placement. Results: Precordial misplacements caused classical changes in ECG patterns.
Techniques of differentiating these ECG patterns from true pathological findings were described. Conclusion: As in Part I of this series,
recognition and interpretation of common ECG placement errors is critical in providing optimal patient care.
Keywords: Cardiology, Electrocardiography, Medical Errors, Precordial Lead Placement, Medical Education (Source: MeSH-NLM).
Introduction
As discussed in Part I of this series, electrocardiography (ECG)
has been established as a useful diagnostic tool.1-3 Accuracy in
ECG recording, whether from trained experts or other medical
professionals, is essential in order to reliably interpret medical
information.4 If ECGs are recorded or interpreted by inexpe-
rienced individuals, results may be incorrectly interpreted, and
patients may be treated according to false information.5-9 There
are characteristic ECG placement errors that can be recognized,
and the REVERSE mnemonic can facilitate recognition of place-
ment errors based on abnormal ECG findings.10
Electrode misplacements have been shown to occur in as many
as 4% of recordings in intensive care units.2,11 When considering
both limb lead reversals and precordial reversals, it is perhaps
easy to imagine how limb leads might be mistakenly applied;
all are long leads, and left and right sides might be confused
on swift application of leads. Contrastingly, precordial leads are
bundled together as a group. This explains the low frequency
of limb and precordial lead reversals.12 Precordial errors iso-
lated to the precordial leads are expanded on more in this
paper, where we discuss complete reversals of leads V1-V6.
Additionally, inaccurate placement of precordial leads poses a
significant problem. Leads V1 and V2 can be placed either too
high or too low, causing characteristic findings in each case.13
This type of error involving V1 and V2 occurs in up to 50% of
ECG recordings.14
The purpose of this study is to review some of the most com-
mon recording errors. For the purpose of clarity, this work has
been divided into two parts. Part I discussed limb lead rever-
sals.2 Part II will deal with precordial placement errors.
Methods
The same subject was analyzed as in Part I of this series, by
the same technician and with the same ECG machine (General
Electric, Mac 5500, United States) set up at 150 Hz, 25.0 mm/s,
and 10.0 mm/V (Figure 1).2 A series of precordial lead mis-
placements were conducted in order to recreate these classic
patterns.
Results
V1-V2 in Third Intercostal Space
RSuperior placement of the V1 and V2 electrodes is a common
error.15 The high position of these electrodes causes the R wave
amplitude to decrease by approximately 0.1mV in leads V1-V2
along with poor R wave progression across the precordial leads
About the Author: Alli-
son Rosen is currently in
her third year of medical
school at Queen’s Univer-
sity, Kingston, Canada. She
is the Editor-in-Chief of the
Queen’s Medical Review
and an active member of
the Class Council.
Submission: Sep 3, 2014
Acceptance: Sep 20, 2014
Process: Peer-reviewed
Correspondence:
Adria n Baranchuk, MD FACC FRCP C. Associate Profe ssor of Medicine, Card iac Electrophysiolog y and Pacing, Kingston General Hospit al, Queen’s University.
Address: Cardiac Elect rophysiolog y and Pacing, Kingston Genera l Hospital K7L 2V7, Queen’s University, Kingston, Canada.
Email: barancha@kgh.kari.net
1Queen’s University School of Medicine, Kingston, Onta rio, Canada.
2Department of Intern al Medicine, Kingston Gener al Hospita l, Queen’s Universit y, Kingston, Ontario, Canada.
3Heart R hythm Service, Kingston General Hospital, Queen’s University, Kingston, Ontario, C anada .
Figure 1. 12 lead ECG depicting correct lead placement. (A)
ECG recording. (B) Correct lead placements on chest and arms.

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(Figure 2).16-19 Furthermore, the key to detecting a high V1-V2
placement is the absence of a positive P wave in V2, accompa-
nied by a biphasic P wave in V1 with a predominantly negative
component. However, the negative P wave in V1 is noted to be
more important for discrimination purposes than V2 findings.5,20
These findings can mimic an anterior or anteroseptal myocar-
dial infarction, however, a negative P wave in V2 in conjunction
with a biphasic P wave in V1 is not common in acute coronary
syndromes. Furthermore, misplacement of V1-V2 electrodes
can be confirmed by recording normal R wave progression from
lower locations on the thorax. If an anterior infarct was the
cause of the poor R wave progression, it would persist in the
lower leads.17 The superior placement of V1-V2 electrodes can
also potentially mimic Brugada syndrome.13 Brugada syndrome
is a potentially lethal cardiac channelopathy that presents with
distinct patterns in the right precordial leads V1, V2, and V3.21,22
The type 1 pattern has high sloping, coved type ST segments
with negative T-waves. The type 2 pattern has high elevated,
saddle back ST segments with variable or flat T-waves in V1 or
V2. Brugada syndrome can be mimicked by a number of cau-
ses, including improper use of high and low-pass filters, and
can be difficult to observe in patients with cardiac abnormali-
ties such as arrhythmias,23-25 r’ waves in leads V1-V2,26 or pec-
tus excavatum.27 As Brugada syndrome is potentially lethal, but
also easily obscured by filters or other errors, it is important
to carefully ensure none of these errors persist if the diagnosis
is suspected.28 Brugada syndrome can be differentiated from
electrode misplacement by noting an absence of the clinical
criteria required for diagnosis along with a normalization of
the ECG upon placing the electrodes on lower locations on the
thorax.29,30
V1-V2 in Fifth Intercostal Space
Inferior placement of the V1-V2 electrodes does not produce a
significantly altered ECG, and can go unrecognized in many ca-
ses (Figure 3). The major change noted is that the low position
of these electrodes can cause the R wave amplitude to increase
by approximately 0.1mV in leads V1-V2 per inferior interspace.17
V1-V6 Reversal
Exchanging two or more precordial leads is another common
error.31 The major finding in these errors is abnormal progres-
sion of the R wave in the affected leads (Figure 4). In a normal
ECG, lead V1 shows an rS-type complex, with a steady increase
in the size of the R wave and decrease in the S wave amplitude
as it moves towards V6. Leads V5 and V6 will predominantly
show a qR-type complex. However, in the case of precordial
lead reversals, one or more electrodes have a marked deviation
from this progression, and this standout area is representative
of the misplaced precordial lead or leads.5,20 In this specific
case, the ECG shows an unexpectedly tall R wave in V1 and a
deep S wave in V6. As these two leads do not follow the ex-
pected pattern, it should raise the suspicion for a V1-V6 lead
reversal.
On a quick examination of the ECG, a V1-V6 reversal can be po-
tentially misinterpreted as a right bundle branch block (RBBB).5
However, a RBBB presents with a RSR’ pattern rather qR-type
complex. Additionally, the lateral leads (I, aVL, V5-V6) may pre-
sent with a wide, slurred S wave along with ST depression and
Figure 2. 12 lead ECG depicting V1 and V2 pla-
ced in the third intercostal space. (A) ECG recording.
(B) Arrows point to reversal of leads on precordium.
Figure 3. 12 lead ECG depicting V1 and V2 pla-
ced in the h intercostal space. (A) ECG recording.
(B) Arrows point to reversal of leads on precordium.
Figure 4. 12 lead ECG depicting reversal of V1 and V6. (A) ECG
recording. (B) Arrows point to reversal of leads on precordium.
Figure 5. 12 lead ECG depicting complete rever-
sal of leads V1-V6. (A) ECG recording. (B) Arrows
point to reversal of leads on precordium.

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T wave inversion in V1-V3, neither of which are observed in a
V1-V6 reversal. A V1-V6 reversal can also be mistaken for right
ventricular hypertrophy (RVH).5 While RVH has a dominant R
wave in V1 and a dominant S wave in V5 or V6, there is also
a right axis deviation, which is not observed in a V1-V6 lead
reversal.
It is important to note that swapping of precordial leads with
limb leads may occur, but is rarely noticed, since the physical
bonds between the six precordial leads makes this misplace-
ment difficult.31
V1-V6 Complete Reversal
A complete reversal of all the precordial electrodes results in
the reversal of the R wave progression. The R wave will decrea-
se its amplitude from V1 to V6 and the S wave will increase its
amplitude (Figure 5). This is similar to findings in dextrocardia
or a posterolateral myocardial infarction.31 Dextrocardia would
present with inversion of P waves and QRS complexes in leads
I and aVL, along with poor R wave progression. Precordial lead
reversal can be differentiated from dextrocardia since limb ab-
normalities would not be found in the case of a reversal.5,20,31 A
posterolateral infarction would present with tall broad R waves
in V1-V3, upright T waves and horizontal ST depression. While
tall R waves and upright T waves can be seen in the case of a
V1-V6 complete reversal, the ST depressions are not present,
and can help rule out a posterior infarct.
Discussion
Precordial electrode misplacements can lead to morphological
changes on ECG that could potentially be interpreted as pa-
thologic. Common misinterpretations of precordial lead mis-
placements can be myocardial infarction, genetic channelo-
pathies such as Brugada syndrome, bundle branch blocks or
pathologies such as dextrocardia. Electrode misplacements are
common in outpatient clinics and intensive care units.5 Interes-
tingly, incorrect placement of specifically V1 and V2 has been
estimated to occur in 50% of ECG recordings.15 The REVERSE
mnemonic is a tool that outlines the most frequent abnormal
findings on ECG.2,5 Of note to our cases, reversal of precordial
electrodes V1-V6 is identified in the mnemonic. Careful use of
mnemonics such as REVERSE can eliminate errors in ECG recor-
ding and interpretation, leading to a reduction in false findings
and an increase in diagnostic accuracy.

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Acknowledgments
None.
Conflict of Interest Statement & Funding
The Authors have no funding, financial relationships or conflicts of interest to disclose.
Author Contributions
Conception and design the work/idea: AR AB. Collect data/obtaining results: AR SK CS. Analysis and interpretation of data: AR SK CS AB.
Write the manuscript: AR SK. Critical revision of the manuscript: AR SK AB. Approval of the final version: AB. Contribution of patients or
study material: SK CS AB. Administrative or technical advice: CS.
Cite as:
Rosen AV, Koppikar S, Shaw C, Baranchuk A. Common ECG lead placement errors. Part I: Precordial Misplacements. Int J Med Students.
2014 Jul-Oct;2(3):Forthcoming.