Download cardiac corner: name that arrhythmia

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CARDIAC CORNER: NAME THAT ARRHYTHMIA
By Jon Atkinson, BS, RPSGT
T
his is the sixth 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 A2Zzz1.
EXAMINE FIGURES 1 AND 2. These are 10-second and
30-second windows respectively. Proceed as follows:
Step 1. Look at the P wave. P waves are not present and have
been replaced by rather non-descript, polymorphic oscillations of
the baseline.
Step 2. Look at the QRS complex. QRS complexes are present;
all QRS complexes look the same in this example.
Step 3. Examine the relationship between P wave and QRS
complexes. Since there are no P waves present, there is no relationship between P waves and QRS complexes.
DISCUSSION
This article demonstrates the difference in appearance of atrial
fibrillation (Figures 1 and 2) and atrial flutter (Figures 3 and 4.)
Note the rather “dirty” baseline between R waves in Figures 1 and
2. These oscillations (fibrillatory waves) are caused by the chaotic electrical activity occurring in the atria. The AASM scoring
manual recommends scoring “atrial fibrillation if there is an irregularly irregular ventricular rhythm associated with replacement
of consistent P waves by rapid oscillations that vary in size, shape,
and timing.”2
In contrast, Figures 3 and 4 demonstrate well-formed flutter
waves with a sawtooth appearance; there is a less chaotic, but still
inefficient, atrial activity. Although atrial flutter is not specifically
addressed in the scoring manual, the notes to the cardiac rules
state that “significant arrhythmias such as heart block should be
reported if the quality of the single lead is sufficient for accurate
scoring.”2 Clearly this is the case here.
TECHNICAL CONSIDERATIONS
Step 4. Examine the intervals (P-R interval and QRS interval).
The P-R interval is non-existent. The QRS interval is narrow and
within normal limits (0.04 - 0.11 seconds), but it could be wider in
the presence of bundle branch block.
The irregularity of the ventricular rhythm may be better seen at
a 30-second window, but the details of the atrial waveform are best
viewed with a 10-second window. Increasing the amplitude or
changing the lead combination may be beneficial.
Step 5. Examine the rhythm. The rhythm is “irregularly irregular.”
INTERVENTION
Step 6. Determine the rate. The atrial rate is indeterminate. The
ventricular rate is highly variable but is about 72 beats per minute
on the average in these examples.
EXAMINE FIGURES 3 AND 4. These are 10-second and
30-second windows respectively.
Proceed as follows:
Step 1. Look at the P wave. No P waves are present. Instead
there are rapid (280-300/second), distinct, well-formed, sawtoothappearing waves between QRS complexes.
Step 2. Look at the QRS complex. QRS complexes are present,
all of similar appearance.
Step 3. Examine the relationship between P wave and QRS
complexes. There are no P waves; but there are 2, 3, 4, 5 or more
sawtooth waves for each QRS complex.
Step 4. Examine the intervals (P-R interval and QRS interval).
There is no P-R interval since P waves are not present.
Step 5. Examine the rhythm. The atrial rhythm (sawtooth-appearing waves) is fairly regular at a rate of 250-400 per minute due
to the pause. The ventricular rhythm can be regular or irregular. In
this case it is irregular.
Step 6. Determine the rate. The atrial rate is 280-300, and the
ventricular rate is about 70-75 beats per minute, varying between
55 and 100 or more beats per minute.
Your institution should have in place a clear, well-defined policy
describing responses to “emergency” situations and occurrences
including cardiac arrhythmias. The arrhythmias described in this
article, particularly atrial fibrillation, are often seen in the laboratory and may be a chronic condition. Often these patients will
be treated with anticoagulants and beta-blocking agents or other
agents to keep the heart rate in check. In the absence of information in the clinical history and physical examination, patient assessment should occur (including blood pressure, level of consciousness
and chest pain); and the medical director or designee should be
notified. If the arrhythmia is acute or previously undiagnosed and
untreated, the patient is at risk of embolic insult to the brain and
lungs. The Emergency Medical System should be activated if the
patient experiences chest pain or alteration of consciousness, if low
or high blood pressure occurs, or on order of the medical director
or designee.
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.
-RQ$WNLQVRQ%6536*7LVWKH$Zzz Editor. He has been in
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employed consultant in sleep medicine technology. ™
A2Zzz 18.3 | September 2009
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FIGURE 1. 10-SECOND WINDOW.
FIGURE 2. 30-SECOND WINDOW.
FIGURE 3. 10-SECOND WINDOW.
FIGURE 4. 30-SECOND WINDOW.
A2Zzz 18.3 | September 2009