18-lead ECG Information
Vol.4
Synthesized 18-lead ECG:
A New Technology for More Informative
ECG Exam
What is Synthesized 18-lead ECG?
The most common ECG exam is the standard 12-lead ECG. It is simple to measure, has low burden on the
body, and observing the heart from these 12 directions provides a lot of information which has a wide range
of clinical applications.
However, some areas, especially pathological change in the right ventricle and the posterior wall cannot be
observed from the 12-lead ECG.
In order to actually measure the right chest (V3R, V4R, V5R) and back (V7, V8, V9) areas, it is necessary
to use different electrode positions than the standard 12-lead ECG. In particular, electrodes must also be
attached to the patient’s back so that normal suction cup electrodes cannot be used. Also, the patient must be
turned over in some cases and in an emergency it is often difficult to use back electrodes. This complicates
the exam procedure.
Synthesized 18-lead ECG uses the 12-lead ECG waveforms to mathematically derive the waveforms of the
right chest leads (V3R, V4R, V5R) and back leads (V7, V8, V9).
The measurement procedure is the same as the standard 12-lead ECG but more information can be obtained.
V1
V2
V3
syn-V3R
V4
V1
V2
V3
V4
syn-V4R
V5
V5
syn-V5R
V6
V6
syn-V 7
syn-V 9
Standard 12-lead ECG
syn-V 8
Synthesized 18-lead ECG
Synthesized right side leads (V3R – V5R) and
synthesized back leads (V7 – V9) are added
Left midclavicular line
Left anterior axillary line
Left midaxillary line
aVR
aVL
V1
V2
V1
V5R V3R
V4R
V6
V2
V3 V5
V4 V6
V3 V4 V5
Waveforms at
additional positions ( )
were calculated by
electrocardiograph
aVF
Measure 12-lead ECG
Calculate instantaneous
vector continuously
V7 V8 V9
Project the instantaneous
vector on synthesized lead
Make synthesized lead
Synthesized 18-lead ECG:
A New Technology for More Informative
ECG Exam
18-lead ECG Information
Vol.4
Discover Origins of Arrhythmia
There have been many reports about ECG characteristics of idiopathic outflow tract ventricular arrhythmias
(OT-VAs). However, differentiating near regions using the 12-lead ECG still remains complicated and these
methods do not have good results.
Then the usefulness of additional 6 lead ECG (V7, V8, V9, V3R, V4R, and V5R) was evaluated for
differentiating the origin of OT-VAs by synthesized 18-lead ECG which is calculated from standard 12-lead
ECG. (Please see the back side of this paper for detailed information about synthesized 18-lead ECG.)
The patients were divided into 4 groups depending on the successful radiofrequency catheter ablation site:
anterior and posterior of right ventricular OT (RVOT-ant-group, RVOT-post-group), right coronary cusp or
junction of these two cusps (RCC-RLJ-group), and left coronary cusp (LCC-group) The QRS morphology
patterns in synthesized V5R at each site were categorized into 4 types: Rs, rS, q and R.
As shown in Table 1, high sensitivity and specificity indicates the utility o f synthesized 18-lead ECG as a
parameter and the QRS morphology pattern in synthesized V5R is useful to precisely differentiate the origins
of OT-VAs.
Table 1
n=9
n=9
n=16
15 (94%)
2 (22%)
1 (11%)
0 (0%)
1 (6%)
7 (78%)
1 (11%)
1 (6%)
0 (0%)
0 (0%)
5 (56%)
0 (0%)
0 (0%)
0 (0%)
2 (22%)
15 (94%)
p
V5R
V5R
TVA
<0.001
V5R
RCC
ant
n=16
RLJ
septum
OT
LCC
RV
R
RCC-RLJ
t
QRS
Rs
In
V5R qR, QS
RVOT-ant
pos
rS
RVOT-post
Figure 1
Representative synthesized
V5R ECGs
V5R
NCC
LCC
V5R
MVA
Reference
The QRS morphology pattern in V5R is novel and simple parameter for differentiating the origin of idiopathic outflow tract
ventricular arrhythmias
Igarashi M, Kuroki K, Adachi T, Yui Y, Ito Y, Ogawa K, Talib A, Sekiguchi Y, Nogami A, Aonuma K, ESC congress 2014
August 30 - September 3; Fira Gran Via, Barcelona, Spain
8029
SP64-045 ’14.08. SE. C