Key result
In isolated rabbit hearts, Wenckebach phenomenon was due to depressed A-V node conduction, while Mobitz type 2 block was due to block in/below His bundle or concealed re-excitation.
This preclinical study demonstrates that Wenckebach block is primarily due to A-V node depression, whereas Mobitz type 2 block occurs in or below the His bundle or via concealed re-excitation.
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Does not support direct clinical application; leaves open translation of site-specific AV block mechanisms to humans.
Mechanisms of clinically known varieties of second degree A-V block were studied in isolated rabbit hearts, utilizing ultramicroelectrode techniques. Progressive A-V conduction delay in Wenckebach phenomenon was due mainly to depressed conduction within the A-V node, while Mobitz type 2 block was due to either block in or below His bundle or concealed re-excitation in the A-V junction. Two levels of block were demonstrated both in forward and retrograde A-V transmission.
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Watanabe et al. (1967) studied Second degree A-V block. Ultramicroelectrode techniques was evaluated on Mechanisms of A-V block. In isolated rabbit hearts, Wenckebach phenomenon was due to depressed A-V node conduction, while Mobitz type 2 block was due to block in/below His bundle or concealed re-excitation.
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