Origin of the Heartbeat/ECG DSA Flashcards
what is the order of depolarization
SA node -> AV -> bundle of his-> purkinje fibers
what is the order of repolarization
“last to depolarize is the first to repolarize”
why is there a delay at the AV node
time to allow the ventricles to fill before contracting
what are the normal leads called
standard limb leads or bipolar leads
where does lead 1 go
Left arm (+) to right arm (-)
where does lead 2 go
right arm (-) to left leg (+)
where does lead 3 go
left arm (-) to left leg (+)
what does lead 1 show
left to right conduction above the heart
what does lead 2 show
conduction along the right side on a diagnonal
what does lead 3 show
conduction along the left side on a diagonal
what lead is at the right leg
the ground
how are the unipolar and augemented unipolar leads different
the augmented ones have 1 node active and the other two are used to be the negative instead of 1 pos and 12 neg
what is the top right augmented lead called
aVR
what is the top left augmented lead called
aVL
what is the bottom left augmented lead called
aVF
what are the 6 chest leads
V1-6
what does the p wave correlate to
SA node and atrial depolarization
what does the PR interval correlate to
electrical trip from the SA node to AV node and the resulting pause in the AV node itself
what does the QRS complex correlate to
ventricular depolarization
what does the T wave correspond to
ventricular repolarization
what does the QT interval correspond to
total time that the ventricle is depolarized
what does the ST segment correlate to
Absolute refractory period of the ventricles
what rate is the standard ekg recorded at
25mm/sec
what is the x axis of the ekg show? y axis
time; mV
1 horizontal ekg line is how many seconds
0.04
1 vertical ekg line is how many volts
0.1 mV
what does the QT interval measure
total time that the ventricles are depolarized
what does the RR interval measure
HR; 0.6 seconds is 60 bpm, 1 sec is 100 bpm
how do you calculate HR from RR interval
- figure mm between two R waves
- multiply that by 0.04 sec/square
- take the inverse and get beat/sec
- multiply that by 60 to get bpm
60/(0.04*RR)
what does the mean electrical axis form
Einthoven’s triangle
what is mean electrical axis
vector addition of two leads (0 to 90 normal)
what is a mean electrical axis in q1? q2? q3? q4?
left axis deviation; extreme axis deviation; right axis deviation; normal
how do the ekg waves and intervals match with cardiac phases
p wave = phase 4 qr = phase 0 rs = phase 1 st = phase 2 t wave = phase 3
