The position of the electrodes allows the operator to inspect a particular view of the heart’s electrical pattern (imagine taking pictures from different angles of the heart). Each view corresponds to a specific lead. It is good practice to identify the waves, complexes, and intervals of different leads and to be familiar with the normal findings at each given lead (see Figure 2.4).

Figure 2.5 ECG Patterns at Different Limb Leads

12-Lead ECG

When analyzing arrhythmias, a single lead that most likely represents all the basic waveforms is selected for use. This lead becomes the monitoring lead. Lead II is the most frequently used monitoring lead.

Figure 2.6 ECG lead placements

Varying ECG Lead Placements on the Body