ECGs

J point

Where the QRS complex ends and the ST segment begins.

What does the PR interval represent and how long should it be?

Time for impulse to travel from atria > ventricles. 0.12s - 0.20s

What does the QT interval represent and how long should it be?

All the electrical activity in 1 ventricular cycle. 0.360s - 0.440s

T wave

Repolarisation of ventricles.

Should be 0.120

0.20s (3-5 boxes)

Should be 0.360s

0.440s (9-1a boxes)

Rate

what is the rate

It should be between 60

100bpm

Rhythm

what is the rhythm

P wave

is there a clear P wave

QRS duration

is it

ST segment

is there any ST elevation/depression

P wave

Atrial depolarisation.

What does the QRS complex represent and how long should it be?

Ventricular deploarisation. Less than 0.12s.

ST segment

Early ventricular repolarisation.

Absolute refractory period

Early phase of ventricular repolarisation wherein the heart muscle can't be stimulated to depolarise.

relative refractory period

The late phase of ventricular repolarisation wherein it is difficult but possible to stimulate depolarisation.

6 basic rules of ECG interpretation

1. Rate 2. Rhythm 3. P wave? 4. PR interval length 5. QRS duration 6. ST elevation/depression?

Lead I view

Lateral wall (high).

Lead II view

Inferior wall.

Lead III view

Inferior wall.

Lead aVL view

Lateral wall (high).

Lead aVF view

Inferior wall.

Lead V1 view

Septum.

Lead V2 view

Septum.

Lead V3 view

Anterior wall.

Lead V4 view

Anterior wall.

Lead V5 view.

Lateral wall (low).

Lead V6 view

Lateral wall (low).