What is the rate of the Bundle of His/Purkinje fibers?

The Bundle of His and Purkinje fibers are part of the heart's conduction system, responsible for delivering electrical impulses to the ventricles, leading to their contraction. These structures have intrinsic rates that are typically lower than the sinoatrial (SA) node and atrioventricular (AV) node, which are responsible for initiating and regulating the heart rate under normal physiological conditions.

The intrinsic firing rate of the Bundle of His and Purkinje fibers usually ranges from 20 to 40 beats per minute (BPM) when they act as pacemakers due to failure of the primary nodes. While there might be some variability in different sources, the average is generally reported around this range.

The assertion that the rate is more than 40 BPM does not align with the established understanding of the intrinsic pacing ability of these fibers. Therefore, it’s essential to understand the normal physiological function and the context in which these fibers take over pacemaking.

In cases where the SA and AV nodes are not functioning effectively, the Bundle of His and Purkinje fibers can provide a backup pacemaking role, albeit at a slower rate, further emphasizing the importance of knowing the typical rates associated with these cardiac structures. This biological basis is crucial for assessing cardiac conduction