Optimized Positioning of ECG Electrodes for WSN Applications - Application and Multidisciplinary Aspects of Wireless Sensor Networks - page 186

Table 9.2 Main characteristics of limited lead systems
Lead System Name

Year Leads Evaluation

EASI, Dower at al. 1988 Three bipolar Numerous studies

Wei 2002 I, II, V1, V6 113 Subjects

Drew et al. 2002 I, II, V1, V5 649 Subjects

Robertson et al. 2002 RV2, RV4, RV6, and RV1, RV2, RV4 64 Subjects

Nelwan et al. 2004 I, II, V2, V5 38 Subjects

the 12-lead ECG could be accurately reconstructed when as many as four precor-
dial leads were removed. In another study [ 16 ], 24-h ECG recordings were ana-
lyzed. Reconstruction of up to four leads was shown to be possible. In a further
study [ 17 ], 12-lead ECG reconstructed from a system consisting of leads I, II, V2,
and V5 was compared with the standard 12-lead ECG. This new lead system recon-
structed the traditional ECG even more accurately, in terms of root means square
error, than the EASI lead system.
Wei [ 3 ] also used a subset of a standard set of leads in conventional 12-lead ECG for
reconstructing 12-lead ECG. Leads I, II, V1, and V6 were investigated for their recon-
struction ability. Both waveform shape and diagnostic information were compared
between the reconstructed and original signals. Wei concluded that this system had a
significant advantage over the EASI lead system. One of the advantages was that sev-
eral of the 12-lead signals were measured directly and therefore needed no
reconstruction.
Drew et al. [ 4 ] used a lead set that differed from Wei's lead set in only one lead,
using V5 instead of V6, making it a lead set of: I, II, V1, and V5. This system was
evaluated on 649 subjects. The authors concluded that 12-lead ECG derived from
this set of leads was valuable for diagnosing multiple abnormalities, including
wide-QRS-complexes, tachycardia, and acute myocardial ischemia/infarction.
Robertson et al. [ 18 ] introduced two limited lead sets consisting of bipolar leads.
The first used V2, V4, and V6 precordial leads, which were measured against right-
arm potential. The other bipolar lead system also used right arm as one side of the
bipolar lead, but with V1, V2, and V4 precordial leads.
Most of the listed lead systems have been evaluated in terms of their diagnostic
value. However, because of huge number of possible abnormalities it was not
proven that all abnormalities can be detected with the same accuracy as with the
standard 12-lead ECG. The main characteristics of the limited lead systems are
summarized in Table 9.2 .
The underlying principle of the reconstruction method for all limited lead sys-
tems is the transformation of information recorded from a limited lead system to
the target lead system [ 1 ]. A set of transformation coefficients is defined on the
basis of optimization and statistical approaches. The transformation that is most
often used and proven to be effective and simple is linear transformation:

S LL L L = + +…+ +…+ aa a a (9.5)

11 22 i i pp