ACLS Review

22 ACLS (Advanced Cardiac Life Support) Review ...
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Identify the relative refractory period on an ECG.
The down slope of the T wave. During this period, it is possible to stimulate the cardiac cells to depolarize, which
may precipitate V-tach or V-fib.
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What is located at the AV junction?
The AV node and the nonbranching portion of the bundle of His.
What occurs during the QRS complex?
Ventricular depolarization.
How is the P–R interval measured?
From the beginning of the P wave to the beginning of the QRS complex.
How is the QT interval measured?
From the beginning of the QRS complex to the end of the T wave.
T/F: The QT interval represents the time required for ventricular depolarization and repolarization.
True.
Contrast a junctional escape rhythm from that of a ventricular escape rhythm.
A junctional rhythm is supraventricular in origin and the QRS complex will be 0.10 seconds or less. Ventricular
escape rhythms are derived from the ventricles and will have a wide QRS complex greater than 0.12 seconds.
Trace the normal electrical flow through the heart.
SA node to the AV node, then to the bundle of His where it is divided into the left and right bundle branches, and
then to the Purkinje fibers where mechanical cells are stimulated.
What is the inherent rate of the AV junctional or nodal rhythm.
40–60 beats per minute.
What are the key features of third-degree AV block?
P waves occur regularly and there are more P waves than QRS complexes.
The ventricular rhythm is regular.
The atria and ventricles beat independently of each other.
The QRS may be narrow or wide depending on the location of the escape pacemaker.