Vertical displacement of the precordial leads alters electrocardiographic morphology

The present study was undertaken to assess whether the vertical displacement of electrodes affects the waveforms of precordial leads.

Two hundred forty healthy, adult volunteers had a standard 12-lead electrocardiogram, a 12-lead electrocardiogram with the precordial leads displaced 2 cm cranially, and another with the precordial leads displaced 2 cm caudally from the standard positions. All the three sets of electrocardiograms were visually compared, and changes noted. One hundred twenty male and 120 female volunteers, 20-68 years of age, were analyzed. Fifty-four males (45.0%) and 2 females (1.7%) showed no difference between the 3 sets of electrocardiograms, while 66 males (55.0%) and 118 females (98.3%) had some changes. R wave amplitude changes were noted in 63 male (52.5%) and 111 female (92.5%) volunteers; S wave amplitude changes were seen in 59 males (49.2%) and 99 females (82.5%,); T wave changes in 5 males (4.2%) and 3 females (2.5%); ST segment changes in 1 male (0.8%) and none of the females; and ORS morphologic changes in 1 male (0.8%) and 12 females (10.0%).

Precordial electrocardiographic waveform changes were seen with the vertical displacement of the precordial leads. This will have implications on the interpretation of serial electrocardiograms. Healthcare providers should take into consideration this deviation when interpreting serial ECGs.