Page 201 - Critical Care Nursing Demystified

186 CRITICAL CARE NURSING DeMYSTIFIED

• RHYTHM: Irregular at the PJC as it comes early.
• CONDUCTION: Other conduction intervals are normal except there is
no PRI.

Junctional Rhythm
Think of a junctional rhythm as PJCs strung together creating a sustained
rhythm coming from the AV junction.

• RATE: No atrial rate as no P waves; ventricular rate is 40 to 60.
• RHYTHM: The rhythm of the ventricles is normal.
• CONDUCTION: No PRI but the QRS and QT are within normal ranges.
The QT interval can be prolonged.

NURSING ALERT

Sustained junctional rhythms have the capacity to slow the cardiac output down. So
look for an underlying cause but monitor the patient closely for decreased cardiac
output signs/symptoms.

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Think of any type of atrioventricular block as a roadblock between the atria and
ventricles. Just like with road construction, the car will get there, but it will take
longer depending upon the type of roadblock. There are three types of AV
blocks: first degree, second degree (with two types: Wenckebach [Mobitz I] and
Mobitz II), and third degree. These roadblocks in the heart affect the PRI pri-
marily but can have consequences for the other characteristics as well.

First-Degree AV Block
A first-degree AV block affects the conduction between the atria and ventricles
by simply prolonging the PRI.
• RATE: This is usually superimposed on an underlying rhythm.

• RHYTHM: Normal.
• CONDUCTION: PRI is prolonged beyond .20 seconds. Everything else is
normal. The problem is above the ventricles or supraventricular.

Second-Degree AV Block—Type I (Wenckebach or Mobitz I)
A second-degree AV block has two types and is a bit more complicated to learn.
It involves changes in the PRI as well. Wenckebach is sort of like a weight lifter