Intra- and interpersonal variation in body surface potentials of healthy subjects

Background: Body surface potential mapping (BSPM) can provide a detailed assessment of cardiac electrical activity and might be of potential added benefit in multiple cardiac diseases. Normal intra- and interpersonal variation in BSPM is not clearly described and could be of use in the distinction between normal variation and cardiac disease development. Objective: The purpose of this study was to describe the effects of normal respiration, changes in body position, repeated electrode placement, and heart rate differences on BSPM signals in a healthy population. Methods: Sixty-seven–lead BSPM was performed in healthy individuals during the resting supine position, a reclined position of 45°, an exercise-increased heart rate, and a follow-up measurement in the resting supine position after 1 week to determine the effect of repeated electrode placement. R-, S- and T-wave amplitudes in all leads were compared between the baseline supine position and the aforementioned conditions. Results: Ten subjects were included {5 (50%) male; median age 28 years (interquartile range [IQR] 26–30 years)}. The R-wave showed the greatest amplitude variation across all conditions, with the largest changes caused by repeated electrode placement (maximum decrease –0.63 mV [IQR −0.69 to −0.22 mV]) and normal respiration (maximum increase 0.32 mV [IQR 0.08–0.55 mV]) and the smallest changes due to reclined position (maximum decrease −0.23 mV [IQR −0.28 to −0.15 mV]). Electrodes near standard precordial positions were most affected. The exercise-increased heart rate reduced the R-wave amplitude in left-sided electrodes and increased the S-wave amplitude in middle superior electrodes. T-wave amplitude generally increased after exercise. Conclusion: Normal intrapersonal variation in BSPM signals was analyzed. Repeated electrode placement and normal respiration caused the largest amplitude changes. These findings may help differentiate normal variation from pathological changes in BSPM.