EKG Interpretation
11-9-11
So we don’t get overwhelmed, let’s start with what we
know and with the easy ones. The EKG is in grids for
measurement.
Horizontal lines mark TIME. (Horizontal is left and right
or along the horizon).
/-------------------- 3 seconds----------/
Then we look at what makes the electrical impulses in
the first place. The Answer is voltage. The higher the
squiggly mark,the higher the voltage.
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EKG Interpretation
11-9-11
The vertical lines mark VOLTAGE.
Since we know that during several of these grids (that
mark time) we should be seeing several P QRS and T
complexes showing the voltage. However, if we see an
EKG strip that looks like this:
There is no voltage. There is no heartbeat over a
significant period of time. This cardiac standstill. This is
asystole! YIKES!
A normal EKG has all of the waves we learned about and
it looks like this:
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EKG Interpretation
11-9-11
The first little bump is the P Wave and looks rounded,
like it should. It is followed by the big upside down QRS
complex and it looks fine. Then the last bump is the T
wave and it is fine. We don’t really see the U wave here
and since we aren’t telemetry techs, we aren’t going to
worry too much about the U wave.
So the strip above and below this text represents normal
sinus rhythm. (Isn’t it pretty?!)
normalsinus.blogspot.com/
What about identifying fast and slow heart beats?
Just don’t panic when you look at an ekg strip and jump
to conclusions! Remember to look at how even the QRS
complexes are to one another (REGULAR) and how many
of them there are.
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EKG Interpretation
11-9-11
On this
strip we see that the P, QRS and T waves all look pretty
normal. In addition, the distance the QRS complexes are
apart, is pretty even or regular. So, the main problem
with this Ekg strip is that the heart is beating too slow.
So we know that this is bradycardia.
A person may
panic when looking at this strip and say that the T waves
and P waves are close together or whatever. As I said
before, just don’t panic. Count the QRS complexes. Gee,
there sure are a LOT of them! This person is tachycardic.
Ask yourself, what kind of reasons could the heart have
for suddenly going fast. We know that if the cells of the
body do not get enough oxygen, they put out a signal. If,
for example, there has been a big loss of blood, the body
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EKG Interpretation
11-9-11
will not have enough red blood cells to carry oxygen. The
heart responds by circulating around what rbc’s are left,
in a big dang hurry! Yes, hemorrhage is one of the
reasons a heart may speed along.
Great, now we know normal sinus rhythm, asytole,
bradycardia and tachycardia.
Next, we will show the wild roller coaster which is
Ventricular Tachycardia because V tach is easy to
recognize. It looks like this:
and this:
and this:
Ventricular Tachycardia
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EKG Interpretation
11-9-11
Why is it far worse for the Ventricles to quiver and be
ineffective than if the Atria quiver and are ineffective? I
mean, after all, a person with A fib can walk in a clinic,
sign a consent form, get medicated, and get shocked
back to a normal rhythm, but a guy with V Fib isn’t going
to be talking to anyone or awake enough to be signing
any consent forms!
The answer to this question is that the atria are small and
do not contribute as much to pumping the heart as the
ventricles do!
The only good thing you can say about V tach is that at
least there IS some cardiac rhythm in order to shock it
into a normal sinus rhythm. With asytole,(cardiac
standstill), the experts say that defibrillation does not
work and that when asytole occurs outside of the
hospital, only about 2% of its victims survive!
============================================
Now let’s move on to P Waves:
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EKG Interpretation
11-9-11
The P wave corresponds to the atria. An absent P Wave
means something is wrong with the atria such as atrial
fibrillation. Absent P Wave looks like this:
Absent.
Absent P waves have four causes:
 Atrial fibrillation
 Sinus arrest
 Sinoatrial block
 Hyperkalaemia
What if there are TWO P Waves? Two P waves mean 3rd
degree heart block which must be treated immediately.
A pacemaker or defibrillator may be necessary.
Two P Waves.
Two P Waves = 3rd Degree heart block.
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EKG Interpretation
11-9-11
www.emsvillage.com/articles/article.cfm?id=684
3rd degree heart block
3rd degree heart block
www.sciencephoto.com/image/272870/large/M4600...
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EKG Interpretation
11-9-11
Why do they talk so much about measuring the PR
interval? What is the PR interval anyway? The PR
interval is the delay time. This is the time between the P
Wave and the QRS complex. This is the time it takes the
impulse to come from the atria and travel through the
AV node and into the left bundle branches. This PR
interval is a very short “time out”.
Think of it like this: When it comes to the four chambers
of the heart, the atria are the little guys. They are
smaller than the ventricles. We will call them the Atria
Brothers: Lefty and Righty. Being a good buddy to his
small friends, “AV node” shows his concern for them by
slowing down this lightening fast electrical impulse in
order to give his friends a change to finish their job of
pumping out their blood out of the top chambers of the
heart and into the bottom chambers of the heart
BEFORE the big strong Ventricle Brothers start in. The
delay helps prevent kick back of blood. In fact, if it
wasn’t for good old buddy “AV”, then the little Atria
Brothers would get overwhelmed by the Ventricle
Brothers.
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EKG Interpretation
11-9-11
Or, to think of it another way, let’s say that “AV node” is
a telegraph station. He gets the message from Master
Node (SA node) that he is supposed to pass on, telling
the big stagecoach to leave the station. But he knows
that it would be better if his two small friends on
horseback got to pull into the station and tie up their
horses BEFORE the big coach takes off or else his little
friends might get bucked off their horses. So, being the
good buddy that he is, “AV” waits a fraction of a second
before he passes the message on. This delay is only .12
to .20 of a second. (Like I said, it is REALLY fast!)
However, if this delay is LONGER than .20 of a second,
then the good old AV didn’t merely delay the message,
he blocked it!
If the delay is SHORTER than .12 seconds, the electrical
impulse is not going through healthy and faithful friend
“AV”. We know that if it goes too fast, then the electrical
impulse is traveling from the SA node through another
route and bypassing “AV”. In this strange route, the
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EKG Interpretation
11-9-11
node there does NOT delay the message, which is going
to be really hard on the Atria Brothers.
Atrial Flutter
Atrial flutter is an abnormality of the heart rhythm, resulting in a
rapid and sometimes irregular heartbeat
http://www.google.com/imgres?imgurl=http://www.learnekgs.com/AFlutter%2520LARGE.jpg&imgrefurl=http://www.12leads.com/atrialflutter.htm&usg=__JKMSzjz_AnPzCoV53fNgkjh0f0=&h=413&w=1778&sz=315&hl=en&start=6&zoom=1&tbnid=ulKcD1L0rqXbDM:&tbnh=35&tbnw=150&ei=_Ym6T
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Atrial flutter abnormal electrical path through the atria.
This is why sometimes the solution is to cut the abnormal
pathway (known as ablation).
A. Fib
www.pedcard.rush.edu/.../irregular-fastlrate.htm
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EKG Interpretation
11-9-11
Atrial fibrillation is an irregular and often rapid heart
rate that commonly causes poor blood flow to the
body. The atria beat chaotic and irregular.
Question: What causes wandering on a baseline
ekg?
Answer: sweat and lotion
Question: What happens to the waveform on the
ECG if a lead comes off the patient’s chest?
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EKG Interpretation
11-9-11
Answer: This stops the monitoring process. The
waveform will not be seen on the monitor.
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