The effect of precordial lead displacement on P-wave morphology in body surface potential mapping

The aim of this study was to investigate the variability of P wave morphology recorded in a close distance to precordial ECG leads. The study consisted of 60 cardiac patients. The ECG signals interpolated at points located at a distance up to 7 cm from the precordial lead location were compared to signals recorded from precordial leads. The 67-channel high-resolution ECG data were used. The distortions in ECG signals was increasing with the distance from precordial lead location, were specific for particular electrode and direction of displacement. Up to 5 cm there were not significant changes in values of correlation coefficient in all studied electrode positions. The P-wave morphology changes were prominent in values of delta parameter computed using the distribution function method and in values of normalized root mean square error beyond 2 cm distance from precordial leads V₁ and V₂. No significant ECG morphology changes up to 5 cm from location of leads V₃, V₄, V₅ and V₆ were observed. VI electrode is more sensitive to vertical than to horizontal displacements in contrary to V₂ electrode where horizontal shift in direction to VI position play a key role.