SCORING CENTER: Name that Arryhthmia
By Jon Atkinson, BS, RPSGT
This is the second in a series of recurring
columns that will keep cardiac arrhythmias fresh
in the minds of sleep technologists. The goal is
to present arrhythmias from actual recordings
and to analyze them using the principles
presented in the recent articles on cardiac
arrhythmias in A2Zzz.1
Examine Figure 1 below. This is a 15-second
window. Proceed as follows:
Step 6. Determine the rate. The rate is about 70
beats per minute.
Discussion
The absence of P waves, their replacement
by an ill-defined baseline, and the presence of
normal-appearing QRS complexes indicate that
the arrhythmia is of supraventricular origin
and that the SA node is not functioning. These
observations, coupled with the “irregularly
irregular” rhythm, lead to the conclusion that
Step 1. Look at the P wave. There are no
this is Atrial Fibrillation. The AASM scoring
definable P waves present.
JON ATKINSON,
manual states: “Score atrial fibrillation if there
BS, RPSGT
is an irregularly irregular ventricular rhythm
Step 2. Look at the QRS complex. QRS complexes
associated with the replacement of consistent P waves by
are present and all look the same.
rapid oscillations that vary in size, shape, and timing.”2
Examine Figure 2 on the next page. This is a 30-second
Step 3. Examine the relationship between P wave and QRS
window.
Proceed as follows:
complexes. There are no P waves; therefore, the
P:QRS ratio is less than 1.
Step 4. Examine the intervals (P-R interval and QRS
interval). There is no P wave; therefore, there is no
P-R interval. The QRS interval is narrow and within
normal limits (0.04 - 0.11 seconds).
Step 5. Examine the rhythm. The rhythm is “irregularly
irregular.”
Figure 1. 15-second window.
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A2Zzz 2008
‡volume 17 ‡ number 3
Step 1. Look at the P wave. There are P waves present, and
they look alike.
Step 2. Look at the QRS complex. QRS complexes are
present and all look the same.
Step 3. Examine the relationship between P wave and QRS
complexes. There is a P wave for each QRS and a
QRS for each P wave; therefore, the P:QRS ratio is 1:1.
Figure 2. 30-second window.
Step 4. Examine the intervals (P-R interval and QRS
interval). The P-R interval is between 0.12 and 0.20
seconds. The QRS interval is narrow and within
normal limits (0.04 - 0.11 seconds).
Jon Atkinson, BS, RPSGT, is the AAST President. He has
been in the sleep field for 27 years, and he currently works
as a self-employed consultant in sleep medicine technology.
Step 5. Examine the rhythm. The rhythm is regular.
Step 6. Determine the rate. The rate is about 92 beats per
minute.
Discussion
This sample shows that all characteristics are normal,
except that the rate is too fast for a patient who is asleep.
Classical EKG definitions would consider this to be the upper
limits of normal for Normal Sinus Rhythm. According to the
AASM scoring manual, however, this should be identified as
Sinus Tachycardia. The AASM scoring manual states: “Score
sinus tachycardia during sleep for sustained sinus heart rate
of greater than 90 beats per minute for adults.”2
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References
1.
Atkinson J. Scoring center: scoring cardiac
dysrhythmias - part 2. A2Zzz 2008;17(1):30-32.
2.
American Academy of Sleep Medicine. The AASM manual
for the scoring of sleep and associated events: rules,
terminology and technical specifications. Westchester, Ill:
American Academy of Sleep Medicine; 2007.
Additional Reading
Atkinson JW. Cardiac arrhythmias. In: Butkov N, LeeChiong T, editors. Fundamentals of sleep technology.
Philadelphia: Lippincot Williams & Wilkins; 2007. p. 314-332.
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