OBJECTIVETo explore the effect of reference point on the potential distribution of normal cardioeleclric field of healthy individuals.

METHODSTwo different reference points including central terminal and right forehead were applied to record electrocardiogram simultaneously from 15 testing points (V(1)-V(6), V(7)-V(9), V(3R)-V(8R)) of Wilson lead (RL) and the same testing points (HV(1)-HV(9), HV(3R)-HV(8R)) of head-chest (HC) lead around the torso of healthy individuals. Chi-square test was performed to observe statistical difference between the HCECGs and RLECGs according to different shapes of QRS and T waves.

RESULTSAmong 120 healthy individuals, deformed ECGs appeared in V(1) and HV(3R)-HV(8R) leads, with 20% (24/120) inverted T wave in V(1) lead, 100% (120/120) in V(3R)-V(8R) leads, wide or deep Q wave 100% (120/120) in V(4R)-V(8R) leads. However, in the corresponding HC-lead system, T waves were all positive, and QRS waves were upright as the pattern of rs, RS or qRs. There was statistical difference in the form of ECG between V(1), V(3R)-V(8R) of Wilson lead and the corresponding HC-lead (P<0.05). The distribution of normal cardioeleclric field related to QRS-T wave was of all-round outward shape by HC-lead, and of roughly bipolar shape by Wilson lead for inverted QRS-T wave on the right thoracic surface.

CONCLUSIONThe normal distribution of electrocardial field is determined by the potential of the reference point. The forehead of HC-lead seems to be better than the central terminal as the reference point of the lead system.