ECG collated Flashcards
How are dipoles created in the heart?
Different regions of the heart being polarised or depolarised
What do two dipoles generate?
An electrical field measurable with 2 electrodes
What is the imaginary line connecting 2 dipoles?
Lead axis
Measured potential difference is greatest when?
The lead axis is parallel to the direction of the dipole and 0 when perpendicular
Lead position on a 12 lead ECG?
1= RA- LA
2= RA- LL
3= LA-LL
V1-6
Direction moving towards the the recording (+ve elctrode) gives what type of deflection?
Upwards
Which electrode is the recording electrode?
Positive
Depolarization moving away from positive electrode causes?
Downwards stroke on ECG
What does the P wave signify?
Atrial depolarization
How long does the P wave last?
0.08-0.1 seconds
What does Q wave signify?
Left to right depolarization of the interventricular septum
How long should the QRS complex be?
0.08-0.1seconds
What does the R wave signify?
Depolarization of the main ventricular mass (moving towards recording electrode)
S wave signifies?
Depolarization of ventricles at base of heart (moving away from recording electrode)
What does T wave signify?
Ventricular repolarization
Where do you place lead 1 of an ECG?
4th IC space, RHS
Where do you place lead 2 of an ECG?
4th ICS, LHS
Where do you place lead 4 of an ECG?
5th ICS, mid-clavicular line
Where do you place lead 3 of an ECG?
Halfway between lead 2 and 4 on the rib/between them
Where do you place lead 5 on an ECG?
5th ICS, anterior axillary line
Where do you place lead 6 on an ECG?
5th ICS, mid axillary line
QRS complex signifies?
Ventricular depolarization (<1s)
PR interval signifies?
AV nodal delay
How long should PR interval be?
0.12-0.2s
QT interval signifies?
Depolarization and repolarization of ventricles
What does a small box stand for on an ECG?
0.04s
What does a large box stand for on an ECG?
0.2s
How to find HR on an ECG?
300/no. of large squares between beats
How to find HR if irregular?
no. of QRS in 30 large squares x 10
6 steps to analysing an ECG?
- Verify patient details
- Check date and time ECG was taken
- Check calibration of ECG paper
- Determine axis
- Workout rhythm
- Look at individual leads for voltage criteria changes OR any ST or T wave changes
How to workout rhythm on an ECG?
- Is electrical activity present
- Regular or irregular
- Heart rate
- P waves present
- PR interval
- Each P wave followed by a QRS
- QRS duration normal
How to figure out axis deviation?
Look at lead 1 + aVf and make a comparison
If the axis is normal?
Lead 1= positive
aVf= positive
What is the axis if Lead 1 is positive and aVf is negative?
LAD
What would lead 1 be if the axis deviation is RAD and aVf was positive?
Negative
What are the aVf and lead 1 in intermediate axis?
both negative
Left bundle branch block characteristics?
WilliaM
V1 is w, V6 is M
Right Bundle branch block characteristics?
MorroW
V1= M
V6= W
Pneumonic for bundle branch block?
William Morrow
