The basics of a 12 lead ECG
The basics of a 12 lead
ECG
What is an ECG?
A recording which measures the electrical activity and the rhythm of your heart
Extremely common test used across the hospital for a range of medical conditions.
Indications include:
- chest pain - Pre-op - Lung problems
- Syncope - Drug therapies
- Palpitations - Dialysis
- Dizziness
- SOB
QUICK REVIEW OF HEART
Purpose
Pumps blood to the body
Basic Anatomy
4 chambers
2 sides
4 valves
The ECG: PQRST
P wave:
The atria contracting
QRS:
The ventricles contracting
T wave: Recovery of the heart
‘refractory period’
Performing an ECG
Simple yet ‘personal’ test
Proper skin prep
Placement of the limb electrodes
Placement of the chest electrodes
12 leads/electrodes but 10 ‘wires’
Each lead provides a tracing, which is characteristic of a different view
of the same electrical activity. 12 different angles of the same thing
- E.g: In a heart attack, you can use the leads and what changes
are in each to determine which artery is occluded and causing the MI
Why skin prep?
Ensures good electrode-skin contact which creates a good tracing
Signals are not well picked up just off the top, dead surface of the skin,
so need to get to the underneath layer so the electrolyte can reach the
signals beneath.
Achieved by:
- Abrasion pads
- Alcohol wipes
- Soap and water
- Razors
Artefact
Baseline wander