- 51 Downloads
Alternating Wenckebach periods are episodes of 2:1 block during which there is a gradual increase in the conduction time of conducted beats, terminating in a greater degree of block. Most episodes of alternating Wenckebach periods occur at the atrioventricular (AV) node, but some have also been reported in other structures such as the His-Purkinje system, Kent bundle and the atria. Alternating Wenckebach periods are usually attributed to block at different levels due to transverse dissociation . In this case, the AV node functions physiologically with two levels of sequential block. At the first level of the AV node, one out of every two atrial impulses is blocked. At the second level, the conduction time of the conducted impulses gradually increases until impulses are blocked. This leads to a variable conduction block ratio of 2:1 or 4:1. The mechanism is depicted in Fig. 1.
Conflict of interest
A.W.G.J. Oomen and F.F.J. Rozestraten declare that they have no competing interests.
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.