electrocardiography/reading ecg Flashcards
is the sa node acted on by other cells
no
Spontaneously active cells
what is the p wave
Conducts current down atria & internodal pathways
function of av node
Current slows down more time for atrial muscle contraction
how does current travel down the septum
His-Purkinje system
Rapid conduction through left & right bundles -> Purkinje fibres -> ventricular contraction
how is that complex shown on an ecg
QRS complex of ECG
what is the t wave
Cardiac muscle relaxes & membrane potential recovers/repolarises
T-wave of ECG
what does lead II read
electrical currents from right shoulder to left leg
which lead would have the largest current (biggest deflection of the qrs)
lead II
Electrical current flowing away from the positive electrode results in a negative (downward) waveform display. In Lead II, the R wave is therefore positive. … The closer the mean QRS axis is to the electrical axis of Lead II, the larger the amplitude of the R wave.
qrs is going the exact same direction as the positive component of lead 2
how would the qrs change if lead II wasn’t perfectly parallel with the direction of the current
a lower qrs
less deflection in qrs as not parralell
what is axis deviation
- change in heart position
- change in position of electrical conduction ( one of the right or left bundle branches can de damaged or one more dominant that the other- current goes in a different direction)
where does lead 1 measure
horizontal
ii
right shouled to left lef
iii
left shoulder to right leg
aVF
down the middle
aVR
right leg to left shoulder
