test 3 Flashcards
what is cardiac cycle caused by
electrical (caused by automaticity) (1st)
mechanical (muscular) (2nd)
2 phases of electrical activity
depolarization= active (contract)= systole
repolarization= resting =diastole
two mechanical responses
systole
diastole
systole
contraction
diastole
resting or filling phase
sino atrial node (SA)
rate of 60-100 bpm
depolarization begins
atrial contraction
AV node
40-60 bpm
delays impulse to ventricles; allows for filling
backup pacemaker for SA node
Bundle of His
20-40 bpm
electrical conduction pathway
- SA node
- AV node
- Bundle of His
- Bundle Branches (L and R)
- Purkinje fibers
what consist of Autonomic Nervous System
sympathetic nervous system
parasympathetic nervous system
parasympathetic nervous system
acetylcholine
decreased HR, decreased contractility, vasodilation
sympathetic nervous system
epinephrine and norepinephrine
increased HR, increased contractility, vasoconstriction
difference between 15 lead and 12 lead
12 lead is only on the front where 15 has 3 on the back
cardiac monitoring
continuous monitoring via 3 lead or 5 lead
skin prep, lead placement and appropriate lead selection are very important
ECG graph paper
vertical= measures amplitude
horizontal= measures time
1 box is 0.04 secs
P wave
atrial depolarization
normally indicates firing of SA node
shouldn’t exceed 3 boxes high
PR interval
Atrial depolarization/delay in AV node
beginning of P wave to beginning of QRS complex
should be anywhere from .12 to .20 secs
shorter interval- impulse from AV junction
Longer interval= first degree AV block
QRS complex
ventricular depolarization
0.06 to 0.10 secs
if wide its a slowed conduction
ST segment
look for depression or elevation.
elevation- MI
depression- ischemia, reciprocal changes, digoxin
QT interval
beginning of QRS complex to end of T wave
0.32 to 0.50 secs
U wave
not normally seen
PP intervals (atrial)
is regular when distance between PP intervals is equal
RR intervals (ventricles)
is regular when distance between RR intervals is equal
normal sinus rhythm
60-100 bpm