ECG Flashcards
For an ECG, what is the recording device and recording called?
Recording device - electrocardiograph. Recording - electrocardiogram.
When depolarisation moves towards the recording electrode, what direction is the deflection on the ECG?
Upwards.
When depolarisation moves away from the recording electrode, what direction is the deflection on the ECG?
Downwards.
What type of leads are the 3 standard limb leads?
Bipolar.
What type of leads are the 3 augmented limb leads?
Unipolar.
What are the positive and negative electrodes for leads I, II and III?
I: -ve is RA, +ve is LA. II: -ve is RA, +ve is LL. III: -ve is LA, +ve is LL.
What direction does lead II see the heart from?
Inferior direction.
Why does the T wave look like a positive deflection when charge is moving away from the recording electrode?
Negative charge is moving away from the recording electrode, so looks like positive charge moving towards it.
What is the name of the reference system involving the standard and augmented limb leads?
Hexaxial reference system.
Why are the waves negative in aVR?
Predominant vector is depolarisation moving away from the recording electrode.
What do each of the chest leads look at?
V1+2 look at the septum, V3+4 look at anterior, V5+6 look at lateral aspect.
What happens to the R and S waves moving from V1-6?
R waves progressively increase, S wave progressively decreases.
What are the locations of the chest electrodes?
V1 - 4th intercostal space right sternal edge.
V2 - 4th intercostal space left sternal edge.
V3 - halfway between V2+4.
V4 - 5th intercostal space mid-clavicular line.
V5 - same horizontal level as V4, anterior axillary line.
V6 - same horizontal level as V5, mid-axillary line.
What is usually the size of the reference pulse?
10mm/1mV.
How do you calculate the heart rate by looking at the ECG?
300/number of large squares between R-R interval.