Erroneous electrocardiogram recordings because of switched electrode leads

Abstract

Most electrocardiogram (ECG) recording errors caused by misplaced electrodes are either because of the technician placing the electrode on the wrong extremity or to mismeasuring the position for the chest leads. However, transposing the leads in the acquisition module can produce similar results. The Heart Station at the Veterans Affairs Medical Center, Durham, NC, provides ECG analyses for a number of remote outpatient clinics. Each of these clinics uses a GE Medical Systems Mac 5000 electrocardiographic instrument (GE Medical Systems Information Technologies, Milwaukee, WI, USA) with the ability to transmit the ECG for computer analysis. Because the number of ECGs recorded in each clinic per day is small, either 1 to 2 technicians per clinic are responsible, among other duties, for all ECG recordings. Periodic training and evaluation of competency are carried out. In spite of this quality oversight, the percentage of recording errors because of misplaced electrodes is several fold greater than in the ECGs recorded by the heart station technicians at the medical center. Recently, significant sequential ECG recording errors were detected from 2 of these clinics because of misplaced leads in the acquisition module. In the first situation, 5 ECGs in a row were recorded in which the left arm and left leg leads had been switched. The cause of this problem was not immediately apparent to the overreading cardiologist, but the technicians were notified and asked to be certain to place the electrodes on the correct extremity. The next day, a similar situation occurred. At this juncture, the technicians were instructed to examine the acquisition module. They found that the left arm and the left leg leads had been transposed. The second similar problem resulted in several sequential abnormal recordings in which the amplitude of the R wave in V6 was markedly less than in V5 (Fig. 1 Panel A). In addition, when compared to previously recorded ECGs,