Electrocardiographic Leads and Techniques in Mass Screening

Electrocardiographic methodology was evaluated during the multiphasic screening of 5,795 volunteers from the Philadelphia area. Approximately 20% of the electrocardiograms were abnormal or borderline. An electrocardiographic screening unit could record 100 twelve-lead tracings or more in eight hours. Each unit consisted of a technician and two volunteer assistants, one machine, and two patient electrode cables. The six limb leads were recorded four times as fast as the 12 leads and the three standard leads were recorded five times as fast. The six leads were in 96% agreement and the three leads in 93% agreement with the 12-lead classifications. The effectiveness was calculated from this agreement and from the recording speed. The six leads were found 3.8 times as effective and the three leads 4.7 times as effective as the 12 leads in mass electrocardiographic screening.