LECTURES:
1. Electrodes
2. Vectors & Electrodes
3. Complete ECG Course
4. The EKG Guy Videos

Overview

• Electrodes sense electrical activity in heart (ie, impulses traveling below them) => EKG machine registers activity at electrodes & converts impulses to waves on EKG paper
• Standard 12-lead ECG: 10 electrodes (4 on limbs + 6 on precordium) monitor 12 leads
• “Cameras” providing 3-D image of heart’s electrical activity => EKG
• Electrical impulse moving:
• AWAY from electrode => downward (negative) deflection
• TOWARD electrode => upward (positive) deflection
• PERPENDICULAR to electrode => isoelectric deflection
• Multiple electrodes around heart => 3-D picture of heart’s electrical axis = EKG

Extremity Electrodes

• L-arm, R-arm, N (neutral, R leg), F (foot, L-leg)
• Does not matter if electrodes attached proximal or distal on extremity (best to be uniform)

Chest Electrodes

• V1: 4th intercostal space, R of sternum
• V2: 4th intercostal space, L of sternum
• V3: b/t V2 & V4
• V4: 5th intercostal space in midclavicular line (under L-breast in women)
• V5: b/t V4 & V6
• V6: same height as V4 in midaxillary line; horizontal to V4, so not necessarily 5th intercostal space
• V3R-V6R: right-sided chest leads (on R-chest; mirror to normal L-side placement)
• V3R: R-midclavicular line
• V4R: V4, but R-sided
• V5R: b/t V4R & V6R
• V6R: same height as V4R in midaxillary line; horizontal to V4R, so not necessarily 5th intercostal space
• V7-V9: posterior leads (on back)
• V6 => V7
• V5 => V8
• V4 => V9

Abbreviations: L, left; R, right; b/t, between