Limb Electrodes

The 12-lead ECGThe 12-lead ECG provides 12 views of the heart. The 12 views are generated through only 10 electrodes. Four limb electrodes attach to the inner forearms and calves. The remaining 6 electrodes, labelled successively from V1 to V6, are attached... provides 12 views of the heart. The 12 views are generated through only 10 electrodes. Four limb electrodes attach to the inner forearms and calves. The remaining 6 electrodes, labelled successively from V1 to V6, are attached to the chest to provide precordial views.

The precordial leads are attached to the chest beginning with V1, placed at the 4th intercostal space (ICS) to the right of the sternum. Lead V2 mirrors V1, but to the left of the sternum. Lead V4 is placed along the mid-clavicular line at the 5th ICS. Lead V3 is placed between V2 and V4. Lead V6 is placed on the 5th ICS along the mid-axillary line. For females, precordial leads V3-V5 should be placed under the left breast.

Lead V1 is situated close to the right ventricleThe right ventricle ejects blood through the main branches of the left and right pulmonary arteries to the lungs. The chambers of the heart are the main drivers within an intricate pathway, delivering blood to the lungs for gas exchange.... While technically a septal lead, lead V1 is a precordial chest lead used to differentiate right from left bundle branch blockA bundle branch block must satisfy two criteria - a wide QRS complex and a notch in the QRS complex. To distinguish between a RBBB and a LBBB, first make certain that the rhythm is indeed supraventricular (P waves before.... Lead V1 is often the best lead to search for P wavesA wave generated from the depolarization of the atria; the P wave is upright when originating from the SA node. The P wave represents the depolarization of the right and left atria. The P wave begins with the first deviation.... Because lead V1 monitors both the right and left sides of the heart, lead V1 is not sufficient to differentiate between left and right ventricular ischemic changes (lead V4R is a superior lead in this role).

Table 6.1a outlines the placement of the 4 electrodes. The location of the leads is an important consideration. For the 12 lead ECGElectrocardiogram; also called an EKG; a representation of electrical voltage measured across the chest over a period of time. 1. Six Second ECG Guidebook (2012), T Barill, p. 196 to be an effective tool, electrode placement must be consistent for every 12 lead taken. A common practice is to mark the skin at each electrode (using a pen or marker) with the first 12 lead so that subsequent 12 leads can be compared accurately. Minor lead misplacements can significantly change the ECG waveforms making comparisons dubious at best.

Table 6.1a details the electrode placement for the 4 limbs on a 12 lead ECG.

1. Six Second ECG GuidebookA Practice Guide to Basic and 12 Lead ECG Interpretation, written by Tracy Barill, 2012 Introduction The ability to correctly interpret an electrocardiogram (ECG), be it a simple six second strip or a 12 lead ECG, is a vital skill... (2012), T Barill, p. 138-139