Page 200 - Critical Care Nursing Demystified

Chapter 4 CARE OF THE PATIENT WITH CRITICAL CARDIAC RHY THM DISTURBANCE NEEDS 185

Atrial Fibrillation

Atrial fibrillation is a rhythm where the atrial tissues contract in an irregular,
chaotic, disorganized way. It is estimated that atrial tissues are beating any-
where from 300 to 600 times per minute. Some say they are twitching, so the
P waves are in a “now you see them, now you do not” pattern. Again, since the
large ventricular muscle masses can not beat that fast, the AV node slows and
filters the P waves but in a grossly irregular fashion. So just like in “Where is
Waldo,” it is hard to find the P waves and they are not always countable. Since
the P waves are indeterminate, you can not count atrial rates, atrial rhythm, or
the PRI.
• RATE: Atrial rate is uncountable; ventricular rate is very countable.
• RHYTHM: Since the P waves are uncountable you can not determine an
atrial rate, but QRS intervals can be counted.
• CONDUCTION: You can not get a PRI but you can measure a QRS,
which may be normal or short depending on the rate. Once the stimulus
gets to the AV node, the conduction times are usually regular.

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In atrial fibrillation/flutter, the patient needs to be monitored for heart failure. Eddies

and currents around the AV valves can set up systemic and pulmonary emboli, so
anticoagulation is necessary to prevent blood clot formation. Also, if the ventricular
response is less than 60 or greater than 100, we call it uncontrolled. The underlying
cause must be found and treated or the patient will have too low of a cardiac output.

Junctional Rhythms
Okay, now the pacemaker is traveling again. The pacemaker for this rhythm is
the AV junction, thus the name “junctional” rhythms. We will explore the char-
acteristics of premature junctional contractions (PJCs) and a junctional rhythm
in this section. One of the discriminating factors in junctional rhythms is their
absent P waves and slow rates. The P waves are absent because the atria do not
contract, and because there is no atrial contraction, voila—no P waves.

Premature Junctional Contractions (PJCs)
Like the PAC, these beats fall on some type of underlying rhythm like NSR or SB.
The words in their names tell what they are—premature in that they fall early from
the junction.
• RATE: Atrial rate—no P waves. Ventricular rate usually slow but can be
normal.