Intro to ECGs Flashcards
What is an ECG?
An electrical tracing of the heart showing the hearts generation of electrical impulses which travel in different directions simultaneously - measuring these gives us an idea of the condition of the heart
What are the two types of cardiac muscle cells?
myocardial conduction cells (1%)
myocardial contractile cells (99%)
Function of myocardial conduction cells
create and propagate electrical impulses
Function of myocardial contractile cells
contract to propel blood and have an extended refractory period to allow for complete contraction
4 characteristics of cardiac cells
Automaticity: ability to spontaneously create and impulse by themselves
Excitability: ability to respond to impulses
Conductivity: ability to transmit
Contractility: how well the cell contracts after receiving a stimulus
How quickly does each part of the electrical pathway fire electrical impulses?
SA node = 60-100bpm
AV node = 40-60bpm
AV bundle = 30-40bpm
Bundle branches = 20-30bpm
Purkinje = 15-20bpm
What do electrodes do?
measure the direction and amplitude of the heart’s electrical impulses
different electrodes provide different views of the heart - can work out which part of the heart is not working properly
What is a lead?
view of the heart’s activity between two electrodes
Electrode placement (5 points)
patient should sit still
shave hair
keep electrical devices away
wiggle the green lead if Zoll isn’t picking up the ECG
ask patient not to talk
Which order do the electrodes go on the patient
RIDE YOUR GREEN BIKE
RED = RA
YELLOW = LA
GREEN = LF
BLACK = RF
Lead I
left arm to right arm
Lead II
left leg to right arm
Lead III
left leg to left arm
in the context of ECGs, what does augmented mean?
the ECG machine makes the electrical impulses bigger
