ECG Flashcards
what is the name of the recording device
electrocardiograph
what is the name of the recording
electrocardiogram
what does the dipole represent
electrical vector
what are the components of the electrical vector
magnitude
direction
how is the magnitude determined
by the mass of cardiac muscle that is involved in the generation of the signal
how is the direction determined
by the overall activity of the heart any instant in time and varies during the cardiac cycle
what is meant by the recording electrode
depolarisation moves towards this electrode and gives a upward direction
what does the p wave represent and how long does it last for
Atrial depolarisation
0.08 - 0.10 sec
what does the QRS complex represent and how long does it last for
Ventricular depolarisation
less than 0.1 sec
what does the PR interval represent and how long does it last for
AV node delay
0.12 - 0.2 sec
what does the ST interval represent
Ventricular systole
what does the T wave represent
Ventricular repolarisation
what does the TP interval represent
Diastole
what are the three augment leads
aVR, aVL, aVF
why is aVR inverted
predominant vector is depolarisation moving away from the electrode
what plane of the heart do the chest leads show
horizontal plane
how long does 1 small square represent
0.04s
how long does 1 big square represent
0.2s
how is heart rate calculated from an ECG
300/number of large squares between beats
300/number of large squares between R-R interval
what is the approach to reading an ECG - 8 steps
1 - Is electrical activity present? 2 - Is the rhythm regular or irregular? 3 - What is the heart rate? 4 - P-waves present? 5 - What is the PR interval? 6 - Is each P-Wave followed by a QRS complex? 7 - Is the QRS duration normal? 8 - Then look at individual leads
what does a normal ECG not exclude
MI
Intermittent Rhythm Disturbance
Stable Angina
what is the reference pulse
10mm/1mV
how long is 5 large squares
1 second
how long is 30 large squares
6 seconds
what is the standard calibration
25mm per sec
