Respiration and the ECG: a study using body surface potential maps

Body surface potential maps and an eccentric spheres model of the heart were used to investigate some of the factors that cause the surface ECG to change with respiration. Although the pattern of the surface maps shifted inferiorly with inspiration, the pattern itself did not change significantly, even with deep respiratory movements. However, the temporal ECGs at specific electrodes changed dramatically. The model simulations show that the contribution to the change in amplitude of the surface potential due to lung conductivity and ventricular volume changes is small. It is suggested that the major cause of the surface potential changes with inspiration is due to the change in heart position.