What is the automaticity rate of the Purkinje fibers?

What is the automaticity rate of the Purkinje fibers?

• A. 60-100 bpm
• B. 20-40 bpm
• C. 40-60 bpm
• D. 80-100 bpm

Answer: (B)

Automaticity is the heart’s ability to generate spontaneous impulses, and different parts of the conduction system have their own intrinsic pacing rates. The Purkinje network, while excellent at conducting impulses rapidly, has the slowest inherent firing rate among the main cardiac pacemakers. Its tissue tends to generate impulses at about 20-40 impulses per minute. That’s why, if the SA node and AV node fail, the Purkinje fibers can take over but produce a much slower ventricular rhythm—roughly 20-40 bpm. In contrast, the SA node paces around 60-100 bpm and the AV node around 40-60 bpm, which is why those ranges don’t fit Purkinje automaticity.

Automaticity is the heart’s ability to generate spontaneous impulses, and different parts of the conduction system have their own intrinsic pacing rates. The Purkinje network, while excellent at conducting impulses rapidly, has the slowest inherent firing rate among the main cardiac pacemakers. Its tissue tends to generate impulses at about 20-40 impulses per minute. That’s why, if the SA node and AV node fail, the Purkinje fibers can take over but produce a much slower ventricular rhythm—roughly 20-40 bpm. In contrast, the SA node paces around 60-100 bpm and the AV node around 40-60 bpm, which is why those ranges don’t fit Purkinje automaticity.