12 Lead ECG

Question 1

what’s it looking for?

Answer 1

10 electrodes- 12 different perspectives

Conduction problems
Arrhythmias
Ischemia, infarction
Hypertrophy
Pacer activity
Effectiveness of drug therapy

Question 2

the basics

Answer 2

The standard EKG has 12 leads:
Standard Limb Leads (I, II, III)
Augmented Limb Leads (aVL, aVR, aVF)
Precordial Leads (V1-V6)

The axis of a particular lead represents the viewpoint
from which it looks at the heart

Question 3

electrode placement

Answer 3

Electrodes create an imaginary line, a “lead” which serves as a reference point from which the electrical activity is viewed.
The “lead” is like the eye of the camera: narrow peripheral field of vision looking only at the electrical activity directly in front of it. (from negative to positive, positive looks back on that side of the heart.

Question 4

Coronary artery anatomy

Answer 4

Heart is rotated and tilts to left. PMI, where left ventricle is closest to chest wall
In general, RCA supplies right side of heart. LCA supplies left side of heart.

Question 5

Configuration will differ from each lead

Answer 5

To make an accurate assessment of the heart’s electrical activity or to identify where, when, and what abnormalities occur, the ECG needs to be evaluated from every lead, not just from lead II.