ECG Flashcards
what is the device used to record the ECG?
an electrocardiograph
what is the net dipole?
The progression of the +ve charge followed by the -ve charge, across the heart
define lead?
the IMAGINARY line connecting two electrodes
When is the recordedpotential difference greatest?
When the lead axis is parallel to the direction of the dipole (smallest/ 0mV when parallel to the lead axis)
electrical vector
has components of magnitude an direction
(magnitude determined by the mass of cardiac muscle that is involved in the signal generation, and direction determined by the overall activity of the heart at any one instant, and varies over the cardiac cycle
depolarisation moving towards the recording (+ve) electrode, gives an upwards deflection. True/ False?
True
away gives a downward deflection
where is lead I placed?
RA +ve to LA -ve
Where is lead II placed?
RA -ve to LL +ve
Where is lead III placed?
LA -ve to LL+ve
what is the fourth electrode on the RL for?
earthing the person
wires?
these go from the electrode to the machine (wires are not the same thing as LEADS)
P wave
upstroke through atrial muscle
QRS complex?
upstroke through ventricular muscle
T wave?
ventricular repolarisation (upward deflection because moving in a direction opposite to that of depolarisation)
which parts of the ECG are isoelectric?
the flat parts
PR interval?
largely due to AV nodal delay
ST segment?
ventricular depolarisation (systole)
TP interval?
diastole
augmented leads?
these are unipolar, they view the heart from different angles compared to the standard limb leads
- augmented voltage R (aVR)
- augmented voltage left (aVL)
- augmented voltage foot (aVF)
inverted wave?
-depolarisation is moving away from electrode
poorly resolved wave?
vector is perpendicular to lead axis
well resolved wave?
vector is parallel to lead axis
chest leads?
- 6 more leads for 6 more views
- can look at body in transverse plane
- called “precordial” leads
how many electrodes are involved in ECG?
9
how many views of the heart (leads) are involved in ECG?
12 (not counting the earth electrode)
what is the ECG Rhythm strip?
- prolonged recording of one lead
- usually lead 2
- allows detection of rhythm disturbance
What are the 6 key steps to analysing an ECG?
- Verify patient details: name and DOB
- Check date and time ECG was taken
- Check calibration of ECG paper
- Determine the axis
- Work out the rhythm (ask yourself 7 questions about the rhythm - which are in another flashcard)
- Look at individual leads for voltage criteria changes OR any ST or T-wave changes
What are the 7 questions you should ask yourself when working out the rhythm from an ECG?
- Is electrical activity present?
- Is the rhythm regular/ irregular?
- What is the heart rate?
- Are P waves present?
- What is the PR interval?
- Is each P wave followed by a QRS complex?
- Is the QRS duration normal?
what could an ECG still not detect?
- MI (may or may not cause ST elevation)
- intermittent rhythm disturbance (if suspected - for 24 hr for 7 days recording
- stable angina (do exercise ECG, look for ST changes which are absent at rest)
