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