ECG leads Flashcards
What is the difference between a lead and an electrode?
A lead is a view of voltage between two points (either two electrodes or an electrode and a “central terminal”). An electrode is the physical sticker placed on the body.
The positive pole of any lead is always an __________. The negative pole may be an ________ or a ________.
The positive pole of any lead is always an Electrode. The negative pole may be an Electrode or a Central Terminal.
In a standard 12-lead ECG print-out, the view of each lead (other than rhythm strips) typically has a duration of _______
2.5s
Leads I, II, and III are known as the __________
standard (or bipolar) limb leads
Leads aVR, aVL, and aVF are known as the __________
Augmented (or unipolar) limb leads
Leads V1-V6 are known as the _______
precordial leads
The leads that are usually used as rhythm strips are:
V1, II, and V5
Any lead that contains a “V” in its name has what property?
It is unipolar (i.e. it makes use of the central terminal)
Give the direction of view of each of the limb leads using the hexaxial system.
- I: 0°
- II: 60°
- III: 120°
- aVR: 210°
- aVL: -30°
- aVF: 90°
All 6 limb leads lie in the _________ plane
frontal
List the appropriate placements for each electrode for the precordial leads:
- V1: 4th ICS, just right of sternum
- V2: 4th ICS, just left of sternum
- V3: Halfway between V2 and V4
- V4: 5th ICS at mid-clavicular line
- V5: Halfway between V4 and V6
- V6: 5th ICS at mid-axillary line
Group the leads in a standard 12-lead ECG by anatomical “view”
- Septal: V1, V2
- Anterior: V3, V4
- Lateral: V5, V6, I, aVL
- Inferior: II, III, aVF
- No Grouping: aVR
Describe mathematical relationships between the limb leads
I + III = II (Einthoven’s law)
aVR + aVL + aVF = 0
