Analyzing EKG
Rhythm Strips
Analysis Format
• Pattern recognition … not the most reliable
way to interpret EKG’s.
• The best way is to take it apart, wave by wave,
and interpret exactly what’s happening within
the heart.
Major Categories of Arrhythmias
• Sinus
• Atrial
• Junctional
• Ventricular
• NSR
• The most common
in the healthy heart,
because the normal
pacemaker is the SA
node.
Normal
Sinus
Rhythm
• In order to accurately interpret
EKG’s, you MUST have an
organized format for approaching
arrhythmias.
“Rules” for a specific arrhythmia…
• Each arrhythmia has specific clues such as
wave configurations, rates, measurements,
and wave relationships.
• These “rules” help us determine the type of
arrhythmia we are looking at.
• You must memorize the “rules” for each one
in order to interpret EKG’s
But…
• You sometimes cannot “pinpoint” exactly
which arrhythmia you are looking at, although
the clues or rules of one or two of the
arrhythmias will direct you to be able to
categorize, and narrow the conclusions.
Format (VERY IMPORTANT!)
• Regularity
• Rate
• P waves
• PR Interval
• QRS Complex
Regularity
•
•
•
•
Is it regular?
Is it irregular?
Are there any patterns to the irregularity?
Are there any ectopic (extra) beats? If so, are
they early or late?
How do we determine regularity or
irregularity?
• Measure R-R Interval (RRI).
• Place one point of caliper on R wave, and it
should remain constant.
• A constant R-R Interval would mean a regular
rate.
How Irregular is it?
• Regularly irregular (a pattern of irregularity)
• Basically regular (only a beat or two that
interrupts it)
• Totally irregular (no patterns at all)
Rate
• What is the exact rate?
• Is the atrial rate the same as the ventricular
rate?
How do we measure rate?
• Depends on the regularity of the rhythm.
• If the rate is regular, the best way is to count
the number of small squares between two R
waves and divide the total into 1500, OR
count the number of large squares and divide
into 300.
Simpler but less accurate way…
• Memorize the rate scale,
but the rate has to be
regular to use it.
• 1 large square = 300 bpm
• 2 large squares =150 bpm
• 3 large squares = 100
bpm
• 4 large squares = 75 bpm
• 5 large squares = 60 bpm
• 6 large squares = 50 bpm
Another way, not as accurate, but
quick…
• Count the number of R waves in a 6 second
strip and multiply by 10.
Next step to interpreting…
• You must be able to locate and identify each
wave so that you can understand what is
happening in the heart.
After determining regularity and rate…
• Next, we need to look at the waves.
• P wave, much more reliable than any other
wave.
• Morphology (shape) is usually rounded and
uniform.
• If hypertrophy (enlargement) or diseased,
could change.
Notice the differences…
• The P wave should also be upright, because
the electrical flow is toward the positive
electrode in Lead II, and it originates in the
SA node.
• You will learn later that a P wave can be a
negative deflection, but for now, it is positive.
Is there a P wave or not?
• If you are not sure, set your caliper at about
.20 and go backwards from the QRS complex,
then this will give you a guideline of where to
look.
• Remember…it should be between .12 and .20
seconds behind the QRS because the PRI is
within these measurements.
• P waves are usually regular.
“Losing” waves phenomenon
• Waves can be hidden or “lost” if two electrical
impulses occur at the same time.
• EX: If atria depolarize at the same time that
the ventricles repolarize, the P wave will be
hidden in the T wave.
• The largest wave will usually take over, and
you could see a notch in that wave.
PRI and QRS complexes
• Next, measure these and determine if they are
WNL or not.
• The PRI is considered abnormal if an impulse
took too long to get from the SA node through
the atria and the AV node.
• The QRS is considered abnormal if the impulse
took too long to travel through the ventricles.
• The actual number is not as important as
knowing what happened in the heart to make
the number.
• PRI = P wave + PR segment
• P wave is atrial depolarization, PR segment is
isoelectric (delay in AV node).
• All of this is supraventricular, or above the
ventricles.
AV Node
• Remember…it is the area of the heart with the
slowest speed.
• It is responsible for “holding” impulses until
the ventricles are ready to receive them.
• “Fail-safe” mechanism prevents the ventricles
from having to respond to too many impulses
at once.
Ventricular or Supraventricular?
• Width of the QRS complex is the key.
• If less than .12 seconds, it is supraventricular,
because it is the shortest route through the
ventricles.
• This does not always apply in the reverse.
• Wide QRS could be caused by:
• An obstruction in the bundle branches.
• A supraventricular impulse that cannot be
conducted normally because they are still
refractory from the preceding beat(the cells
are depolarized but not yet repolarized or able
to accept another impulse)
• An irritable focus in the ventricles that
assumes pacemaking responsibility
EKG #1 shows a ”sine wave” pattern
with a very wide QRS from
hyperkalemia. The potassium was
elevated and was due to new onset
severe acute renal failure.
The second EKG shows a junctional
bradycardia, another possible finding
in hyperkalemia.
Next…you are now ready to begin
learning specific arrhythmias!!!
Practice, Practice, Practice!!!
P. 62-69.