Session S63.3

Effects of Electrode Misplacement on the Reconstruction of the 12-Lead ECG

DD Finlay*, SP Nelwan, CD Nugent

University of Ulster
Belfast, UK

Several limited lead systems have been proposed that allow the reconstruction of the 12-lead ECG. One particular system uses standard limb leads along with V2 and V5 to reconstruct the remaining precordial leads. However, without a reference to the other electrode positions, the V2 and V5 electrodes can be slightly misplaced. In this study, we assess the impact, on reconstruction accuracy, of these vertical misplacements. The study population consisted of 117 lead body surface potential maps (BSPMs) recorded from 559 subjects (approximately one third normal, one third MI and one third LVH). The BSPMs were interpolated to increase the number of recording sites in the vicinity of V2 and V5. This facilitated the ability to simulate vertical misplacement of V2 and V5, in 0.5 cm increments up to +5cm and -5cm, away from their actual location. V2 and v5 were moved simultaneously and at each simulated location the missing precordial leads were reconstructed. The RMS error was calculated between the reconstructed and actual leads for the QRS complex and STT segment of each reconstructed precordial lead. For QRS segments the median RMS error across all reconstructed leads was 220.4 microvolts, 171.4 microvolts, 277.8 microvolts at -5cm, 0cm, and +5cm respectively. For STT segments these values were 66.8 microvolts, 54.3 microvolts and 76.9 microvolts respectively. We observed that during the QRS segment the most accurate reconstruction was at -1.5 cm (RMS error: 154.4 microvolts). During the STT segment the reconstruction error was at its minimum at -2cm (RMS error: 48.5 microvolts). A similar increase in performance for STT reconstruction was observed at +1.5cm (RMS error: 48.6 microvolts). When the reconstruction accuracies of individual leads were considered it was found the pattern was similar to that for the median. Namely, the greatest error was apparent at + 5cm and -5cm, but the most accurate reconstruction did not always occur at 0cm. This study has shown that this limited lead system has some tolerance to vertical misplacement (-/+1.5 cm). In future work we intend to also study the effects of horizontal misplacement.

(Abstract Control Number: 61)