unit 5 Flashcards
what is cardiac output? what is the formula?
how effectively the heart is pumping. it is stroke volume multiplied by heart rate
what is the cardiac conduction system, and how do pacemaker cells function?
it is a pathway of speciailized cells that create and conduct electrical impulses. all of these cells are pacemaker cells, which can initiate, respond to, and pass on signals
what is the pathway of electricity in the heart
the SA node, the internodal tracks, Bachman’s bundle, the AV node, the bundle of His, the bundle branches, and the purkenji fibers
what do the internodal tracts and bachmans bundle do
they bring the impulse to the left atrium
what happens to the impulse when it reaches the AV node
it pauses to allow the atria to empty
where do the bundle branches take the impulse
the the ventricles
what is the inherent rate of the SA node
60-100 BPM
what is the AV junction rate
40-60. the AV junction includes the AV node and the Bundle of His, and serves to unite the electrical systems of the ventricles and atria
what is the ventricle rate
20-40
where do all normal rhythms originate
the SA node, they are referred to as sinus rhythms
what is an arrhythmia
a rhythm that originates from any other pacemaker. always abnormal
what is the isoelectric line
the baseline. you use the PR segment as the isoelectric line
intervals include
segments (flat portions) and waves
what do complexes contain
mutiple waves
what does one heartbeat contain
a p-qrs-t sequence
what is the most common lead to evaluate for rate and rhythm
lead 2
what is the morphology of the waves? what happens to morphology if you change viewing leads
shape, it will change
what does the p wave represent. what should it look like
atrial depolarization. round, symmetrical upright, and small
what does the PR interval represent
the artial cycle, not including repolarization
what does the PR segment represent
atrial systole and the pause at the AV node
what does the QRS complex represent
ventricle depolarization
what does the ST segment represent
ventricular systole
what does the T wave represent. what should it look like
ventricular repolarization. broad, round, leaning towards QRS
what does the QT interval represent
the complete ventricular cycle
what is the purpose of the R-R interval
it is measured to determine rate and regularity of rhythm
what does the U wave represent. what should it look like
late repolarization, not usually seen. shallow, broad, and rouded
waht does the Ta wave represent.
atrial repolarization. it is usually hidden in the QRS.
how do you measure the PR interval and what should it be
from the beginning of P to the beginning of the QRS complex. should be 3-5 small boxes, which is 0.12-0.20 seconds.
how do you measure the QRS interval and what should it be
from the beginning to end of the QRS, should be less than 0.12 seconds (3 small boxes).
how do you measure the QT interval
from the beginning of the QRS to the end of the T wave. should be 0.36-0.44 seconds, or 9-11 small boxes
how many boxes is 1 second equivalent to
5 big boxes, 25 small
how many seconds is 1 big box
0.20
how many seconds is 1 small box, how many milivolts
0.04 seconds, 0.1 milivolts
what is heart rate
the number of QRS complexes recorded in BPM
what is the 6 second method
the fastest method but the least accurate, and the only one that can be used on irregular rhythms. count the number of QRS complexes in 6 seconds and multiply by 10.
what is the 1500 method
the most accurate. count the small boxes between QRS complexes and divide 1500 by that number. to find the number of small boxes quicker, count the number of big boxes, multiply by 5, and add the remaining small boxes on either side.
what is the 300 method
the middle accuracy, best with regular rhythms. find a QRS that is on a dark line and count the number of big boxes between the next QRS. divide 300 by the number of big boxes
what is a regular rhythm
a R-R interval that varies by no more than 1-2 little boxes
what is a regular but interrupted rhythm
the underlying rhythm is regular, but an eptopic beat breaks it up, meaning either a pause or a beat that is too fast.
what is a irregular rhythm
R-R varies throughout the tracing
what is regularly irregular
it doesnt meet the defintion of regular but there is a clear repeating pattern
what are the 6 basic steps in EKG analysis
determine the rate in BPM, examine for regularity, determine if the P wave is present and uniform, measure the PR interval, measure the QRS interval, identify the rhyhtm
