ECG Interpretation Flashcards
Limb leads
I, II, III, aVL, aVR, aVF
Precordial leads
V1, V2, V3, V4, V5, V6
Lateral leads
I, aVL, V5, V6
Inferior leads
II, III, aVF
Septal leads
V1, V2
Anterior leads
V1, V2, V3, V4
How long is a typical ECG strip
20 seconds
P Wave (Patria) represents:
Depolarisation (firing) of the atria
Conduction pathway in 6 steps
- SA Node initiates atrial depolarisation causing Pwave.
- Impulse is delayed at the AV Node (PR segment)
- Ventricular depolarisation begins at the apex (QRS) + atrial repolarisation occurs.
- Vent depolarisation occurs (ST segment)
- Ventricular repolarisation begins at the apex (Twave).
- Ventricular repolarisation complete
Normal length of P Wave:
Less than 3 squares or 0.12 seconds
Measurement starts from the start of the P wave and goes to the end of the P wave.
Normal amplitude of a P wave:
Less than 1.5 squares in precordial leads (V1-V6).
Less than 2.5 squares in limb leads (I-III, aVL, aVR, aVF).
A a abnormally large P wave indicates:
A problem with the atria.
E.g. left atrial/right atrial hypertrophy)
Describe the QRS complex waveform:
Q -Initial deflection below the equatorial isoelectric baseline
R - Entire wave above the baseline
S - The entire wave below the baseline
Length of a normal (narrow) QRS:
Less than 3 squares.
The QRS begins from the start of the Q wave and ends after the S wave.
Wide QRS complex indicates:
Blockages along the conduction system (bundle branch blocks)
or
electrolyte abnormalities
When you see the T wave, the ventricles are:
Recharging to fire again (repolarising)
Normal T wave is:
Less than 1 box in precordial leads
Less than 2 boxes in the limbs leads`
PR interval measures from:
Start of the P wave (atrial depolarisation)
to the
Start of the QRS complex (ventricular repolarisation)
Describe the PR interval in simple terms:
Electrical impulse is sent from the Sinoatrial node (SA) to the atrioventricular node (AV)
AV node chills for a bit, and then activates the septum down the Bundle of His to the ventricles
If the AV node is chillin’ too much, then there is some form of ‘heart block’
Normal PR interval:
Less than 1 box/ 5 small squares
PRT segment is useful to look for:
Pericarditis
PR segment is measured from:
The end of the P to the start of the QRS segment
ST segment is measured from:
End of the QRS to the start of the T wave.
Where is the J Point?
The point where the QRS changes slope and becomes the ST segment.
U waves are:
Repolarisation waves.
Not well understood. Show up in a few clinicial scenarios including hypothermia.
The R-R interval is:
The time between each ventricular depolarisation (beats).
QT interval is measured from:
The start of ventricular repolarisation (QRS)
to the
End of ventricular repolarisation (T wave)
A long QT interval indicates:
Ventricular depolarisation while
