Examples of proper ECG lead placement are available through EMTResource.com and the Eccles Health Sciences Library of the University of Utah. Both websites provide diagrams, while the former also provides information about electrode reversal and misplacement.
ECG leads are placed according to two electrical planes, notes EMTResource.com. Frontal leads such as the Lead I, Lead II, Lead III, aVR, aVL and aVF leads observe the heart from a vertical plane, while the remaining transverse leads observe the heart from a horizontal plane, constructing a complete view of cardiac activity.
Leads I, II and III are bipolar limb leads, according to the Eccles Health Sciences Library of the University of Utah. Lead I is a right left or lateral lead, while leads II and II are superior inferior leads. Leads aVR, aVL and aVF are augmented unipolar limb leads to be placed in rightward, leftward and inferior positions, respectively. Leads V1, V2 and V3 are unipolar chest leads to be placed in posterior anterior positions, while leads V4, V5 and V6 must be placed in right left or lateral positions.
Of the 12 leads used to produce an ECG image, only 10 are electrodes, notes EMTResource.com. The nature of the technology used to produce an image of cardiac activity allows 12 different images to be produced from these 10 electrodes.