Anatomy & PhysiologyQuestion 66 of 100
What is the inherent rate of the Purkinje fibers, and what does a rhythm at that rate look like?
a.60 to 100 beats per minute with narrow complexes
b.40 to 60 beats per minute with inverted P waves
c.100 to 150 beats per minute with sawtooth waves
d.20 to 40 beats per minute with wide QRS complexes and no P waves
Explanation
The Purkinje network is the heart's pacemaker of last resort at 20 to 40 beats per minute, and because the impulse starts below the AV junction, the QRS is wide and no P waves precede it. The 60 to 100 range belongs to the SA node and produces narrow complexes with upright P waves. The 40 to 60 range with inverted P waves describes a junctional rhythm, and sawtooth waves indicate atrial flutter.
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