A first look at the ECG Flashcards
what does SLL I stand for?
left arm with relation to right arm
what does SLL II stand for?
left leg with relation to right arm
What does SLL III stand for?
left leg with relation to left arm
What does a fast event mean?
depolarisation and repolarisation of the AP are transmitted well
What does a slow event mean?
e.g the plateau of the AP - depolarisation and repolarisation of the AP are not transmitted well
TRUE OR FALSE
A wave of approaching depolarisation causes an upward-going blip
TRUE
Recording from SLL II
SLL II (from LL wrt RA) difference in potential between the left leg and right arm
The main wave of depolarisation in this case passes down the ventricles and through the body fluids towards the electrode on the left leg
what is an ECG
electrocardiogram
Heart rate is measured at different angles (leads)
what is the normal value for the time taken for PR interval - time taken to transmit depolarisation through the AV node
normally about 0.12-0.2 sec – healthy, any more is unhealthy
what is meant by STEMI and NSTEMI
STEMI - more serious heart attack - elevated ST segment - more tissue damage
NSTEMI - non-ST elevated myocardial infarction
What does the QT interval correspond to? and what is it’s normal range
time spent while ventricles are depolarised
varies with heart rate, but normally about
0.42 sec at 60 bpm
What does the QRS complex correspond to? and what is it’s normal range
time for the whole of the ventricle to depolarise
- normally about 0.08 sec
What values indicate bradycardia (slow heart rate)
below 60 beats per minute
What values indicate tachycardia (fast heart rate)
above 100 beats per minute
How do you measure the Heart Rate off an ECG
measure the R-R (R is main point of ventricular depolarisation- biggest wave) interval and work out how many occur in 60 seconds
