EKG Flashcards
what is the primary pacemaker for the heart?
the SA node
2 body systems that control heart rate
PNS / SNS
what happens during atrial depolarization?
cells become more negative – atrium contracts –> filling of ventricles
Sa node fires- what part of ekg?
p wave
ventricles fillings a lil more = what part of ekg?
PR segment
______ _______ slow down the electrical impulses on their way to ventricles (why do i care?)
transitional cells
◦ This delay allows atrial contraction and ventricular filling
–> represented by PR segment
what is the PR interval composed of? (2 parts)
p wave and PR segment
how long should the PR interval be?
0.2 - 0.10 seconds
what part of EKG represents ventriclular depolarization (contraction)?
QRS complex
can the ventricles start an impulse?
yes! they contain nodal cells which can cause the ventricles to start an impulse but its not what we want - es muy mal
which part of the EKG represents ventricular repolarization?
T wave
which part of the EKG represents early ventricular repolarization?
ST segment
how many pictures of the heart does a 12 lead show us? how many electrodes are there?
◦ 12 lead system has 10 electrodes but shows us 12 pictures
how often do we change the electrodes?
q24 hours
the top 2 leads are placed where?
on the out portion of the 2nd intercostal
what does a positive deflection look like on an ekg?
line rises up
what does a negative reflection look like on an ekg?
dip down
what is it called when a line moves straight across an EKG?
isoelectric
tiny little box. = _____ seconds
0.04
1 big box. = ______ seconds
0.20
5 big boxes = ______ seconds
1.0 seconds
30 big boxes = _______ seconds
6 seconds
how can we calculate the heart rate on an ekg?
count the # of QRS complexes in 6 seconds (30 big boxes) and multiply by 10 = Heart Rate
what should the PR segment look like?
isoelectric
which parts of QRS complex are sometimes not visible?
Q and S
will R be a positive or negative defelction?
positive
What is happening during the QRS complex?
= ventricular depolarization = ventricular contraction = squeezing blood out
what should the ST segment look like on a normal EKG?
isoelectric
what should the T wave look like? what does T wave represent?
• SHOULD be positive, round and symmetrical
= Ventricular repolarization
______ wave Represents slow repolarization of Purkinje fibers in ventricles
U
—> its not normal!
what does the QT interval represent?
=time it takes for ventricular depolarization and repolarization to occur (contract and rest)
normal range for QT interval?
0.36-0.44 seconds
this is an emergency that can happen with a prolonged QT interval and it looks like a party streamer
Torsades de Pointe
causes of artifact on EKG
• Check your patient before you panic… ASSESS
• Interference on the monitor
• Movement
• Old electrodes –> change the electrodes everyday
• Poor contact of electrodes
• Faulty equipment
8 basic steps of EKG analysis
1.Determine HR
2.Determine Rhythm
3.Analyze P waves
4.Measure PR Interval
5.Measure QRS Duration
6.Examine ST Segment
7.Assess T wave
8.Measure QT interval
Step 1 of ekg interpretation - heart rate- how do we do it?
◦ 6-second strip (30 big boxes) rule- count the QRS complexes and multiply X 10
step 2 ekg interpretation- how do we determine the heart rhythm?
◦ Is it regular? Irregular?
◦ March out the beats… P –P interval (first), R-R interval (peak)
step 3 ekg interpretation - how do we analyze the p waves?
◦ Regular occurrence and shape?
◦ 1:1 ratio with QRS? - for every p wave there should be a QRS complex
◦ Do they all look similar to one another?
step 4 eky interpreation - how do we measure the PR interval?
◦ Place caliper points at beginning of P wave and end of PR segment
◦ Count blocks (# of blocks X 0.04) –> Should be 0.12-0.20 seconds
◦ Are they constant? > 0.20? (taking heart longer time to contract atria) < 0.12?
step 5 ekg interpretation- how do we measure the QRS duration? what is normal?
◦ Place caliper points at beginning of QRS and at end of QRS
◦ Count blocks (# of blocks X 0.04)
Should be between 0.04 and 0.10 seconds
◦ Are they constant? More than 0.10? Less than .04?
step 6 ekg interpretation - what are we looking for in the ST segment?
◦ Is it isoelectric? (good) Is it elevated? Is it depressed? (is it elevated or depressed= > one small block (1 mm = 1 lil box), two or more leads?)
step 7 ekg interpretation- what are we looking for in the T wave?
◦ is it rounded and fairly symmetrical? (first bump after isoelectric ST)
step 8 of ekg interpretation - how do we measure the QT interval?
◦ Place Caliper points at beginning of QRS complex and end of T wave
◦ Count small boxes and multiply by 0.04
◦ Can compare to R-R interval and divide by 2 for normal (or 0.36-0.44)
‣ should be < 1/2 of r-r interval
step 9 ekg interpretation =
shake your head and say thank god i’m done looking at that
