Evaluating the Effects of Respiration, Body orientation and Heart rate on Body Surface Potentials in Healthy Subjects

The challenges in tracking disease progression and early identification of cardiac abnormalities have been researched and improvised by 67-lead Body Surface Potential Mapping (BSPM). The BSPM provides spatial, temporal and magnitude insights into cardiac electrical activity, improving the diagnosis by detecting subtle abnormalities. The signal accuracy of two consecutive body surface measurement during patient follow-up may be affected by body orientation, respiration and both natural and pathological heart rate variability. Lacking the evidence to demonstrate, our experiment aims to investigate these effects on body surface potentials in 67-lead BSPM in ten healthy (sinus rhythm) participants with a median age of 28 years. BSPM was performed during inspiratory and expiratory holds, 45-degree reclined body position and exercise-increased heart rate. The median beats were generated and R, S, T amplitudes from all 67 leads were extracted and compared for all the conditions. The difference maps between resting supine condition and other experimental conditions were generated to visualize the positive (red) and negative (blue) potential differences. A 3D generic torso model was utilized to visualize the location of largest positive and negative potentials along with the frequency of their occurrence among ten subjects. The results showed that inspiratory hold and increased heart rate had the highest influence, expiratory hold with moderate and reclined body with smallest effects on the BSPM. The findings from the difference in potential values and lead location may help to increase specificity by distinguishing normal variations from serious conditions such as ACM, ventricular arrhythmias on body surface potentials. It also offers more sensitivity by detecting even very small changes when they are deviating from normal patterns.