18-lead ECG Information

Vol.2

Words on The Occasionof Publication of Study Reporton Synthesized 18-lead ECG
HiroakiShimokawa,DamingWei,

Department of Cardiovascular Medicine,
Tohoku University Graduate School ofMedicine

Director of Biomedical Information
Technology Lab, The University of Aizu

The mortality rate from ischemic heart disease in Japan has
been reported to be 63.4 and 50.0 per 100,000 in male andfemale, respectively. According to the MONICA Study, it
is estimated that the morbidity rates of myocardial infarction(MI) per year are approximately 38 (20-50) and 12 (10-30) inmale and female, respectively (Guidelines for the Managementof Patients with ST-elevation Myocardial Infarction; Japanese
Circulation Society). Needless to say, diagnosis of ischemic
heart disease and acute MI is very important.

Synthesized ECG on Extended Posterior and Right Precordial
Leads − Principle and Clinical Applications

M.D., Professor

Moreover, these guidelines also refer to the importanceof electrocardiograph (ECG) in the management of thesediseases, especially in recording V4R to evaluate possible rightventricular MI and leads V7, V8 and V9 to evaluate possible
posterior infarction. However, these leads are rarely measured
in routine diagnostic procedure. The synthesized 18-lead
ECG to be introduced shows the measurement of right-sided
precordial leads V3R, V4R and V5R and posterior leads V7,
V8 and V9 calculated from measurement of standard 12-lead
ECG.
I believe that combining these synthesized extended leads withstandard 12-lead ECG will enable easier detection of rightventricular MI and posterior infarction than only standard 12lead ECG.
syn-V3R

V1

V2

V3
V4

syn-V4R

Ph.D., Professor

While 12-lead electrocardiogram (ECG) is a clinical standard,
it is not sensitive enough to detect some diseases like acute
myocardial infarction (AMI) taking place on posterior or rightventricular walls. In such circumstances, ECGs recorded fromextended leads on V7, V8 and V9, or V3R, V4R, V5R and V6R
are usually desired. However, it is not only a very complicatedprocess to attach electrodes on the back of the body, but also
standard 12-lead electrocardiograph is not capable of recording
ECG on extended leads during routine clinical recording.
We present a work that synthesizes ECGs on the extended leadsof V7, V8 and V9, or V3R, V4R and V5R using ECG signals
from standard 12-lead ECG recording. The theoretical principleof synthesis is based on information redundancy, so that theextended leads can be expressed by a linear combination ofthe recorded leads for the 12-lead ECG. We evaluated ourmethod using several hundred of clinical ECG data recorded
from Tohoku University Hospital, Nihon University Hospital,and other medical centers. Satisfied accuracy from clinicalapplication standard was obtained, which included correlationsof waveform, and potentials differences between thesynthesized and measured ECGs. The figure shows an example
where the detected and synthesized ECGs of extended leads
are overlapped. This study provides a computer-aided meansfor diagnosis of posterior and right ventricular AMI without
having to record posterior and right precordial ECGs.

V5

syn-V5R

aVR
1000

1000

1000

1000

500

500

500

500

5000

Amplitude ( μ V )syn-V 9syn-V 80000-500-500-500-500-500-500-1000
0-100010-1000
10-1000
10-1000
10-1000
100.5V1syn-V 7aVF

1000

5000V6aVL

10000.5
V20.5
V30.5
V40.5V5

1000

1000

1000

1000

500

500

500

500

500

000000-500-500-500-500-500-5000.5

1-10000V70.51-10000V80.51-10000V90.51-1000
0V3R

1000
500

0.5

1-1000
0V4R

1000

1000

1000

1000

500

500

500

500

500

000000-500-500-500-500-500-500-10000-1000
10-1000
10-1000
10-1000
10-1000
100.50.5
Time(s)0.50.5

1V5R

10000.5

1V6

1000

-1000
00.51000500

0.50.51

Words on The Occasionof Publication of Study Reporton Synthesized 18-lead ECG

18-lead ECG Information

Vol.2

TakaoKato,

M.D., Professor
Department of Internal Medicine,
Nippon Medical School

Synthesized 18-lead ECG, which I presented as researchfindings at a symposium of the International Society of Holter
and Noninvasive Electrocardiology in 2009, is to be introduced
as a viewer on the PC, and now I have a high expectation for
its future applications at actual site.
This synthesized 18-lead ECG method is to derivemeasurements of right-sided leads V3R, V4R and V5R andposterior leads V7, V8 and V9 using ECG signals fromstandard 12-lead ECG recording. Here I’d like to introduce
one of the cases reported by clinic of Nippon Medical School,
where I found this method to be useful in routine diagnosis.
Figure 1 is an ECG of a patient (60 years old, male) with chest
pain obtained at the initial visit on March 8, 2008.
As shown in Fig.1, ST elevation appears in leads II, III andaVF of standard 12-lead ECG, which indicates the patient has
inferior infarction while diagnosis of right ventricular MI isuncertain since ST change is less recognized in leads aVR, V1and V2.

Case 4IIIIn contrast, derived right-sided precordial leads (V3R, V4R,and V5R; Synthesized) clearly shows ST elevation, whichstrongly indicates the patient has right ventricular MI.
Actual ECG waveform (V3R, V4R, and V5R; Actual) recordedby actually placing electrodes also shows ST elevation, whichindicate good consistency of Synthesized and Actual ECG
waveform.Therefore, it can be said that these derived rightsided precordial leads reflect the status of right ventricular MI
well although it would be difficult to diagnose MI extended tothe right ventricular by only standard 12-lead ECG.
When MI is suspected in clinical settings, it is obviously criticalto determine the infarcted area in an early stage and provide
appropriate treatment promptly.This easy-to-use synthesized18-lead ECG method is clinically useful for evaluating thestatus of right ventricular and posterior of the heart, which isdifficult for standard 12-lead ECG.

60-M; STEMI in V3R-V5R
V1

V2

V3R

V3R

V4R

V4R
ActualIIIV3V5R

V5R

V7V7V8V8V9V9Synthesized

Differences

aVR
V4aVL
V5aVF
V6Fig. 1NIHON KODEN CORPORATION

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