Why the study?
Does premature stimulation of the bundle of His simulate cardiac arrhythmias in dog hearts?
Does premature stimulation of the bundle of His simulate cardiac arrhythmias in dog hearts?
Concealed bundle of His extrasystoles can simulate various forms of A-V block and atrial bigeminy in an intact dog heart model.
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Concealed His bundle extrasystoles may underlie apparent A-V block or bigeminy; leaves open clinical relevance pending human data.
In 10 open-chest intact dog hearts, multiple close bipolar electrograms were obtained from various regions of both atria and the bundle of His. The bundle of His was also prematurely stimulated at varying coupling intervals following a sinus beat. At short coupling intervals, the bundle of His stimulus failed to propagate antegradely (no ventricular response) but did propagate retrogradely. Coupled bundle of His stimuli retrogradely concealed within the A-V node caused the next sinus impulse to be delayed or blocked. Types I and II second degree A-V block, 2:1 A-V block, and alternation of the P-R interval were simulated. An atrial (nonconducted) bigeminal rhythm was simulated when the bundle of His stimuli completely traversed the A-V node and completely (inverted P waves) or partially (fusion P waves) depolarized the atria.
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Damato et al. (1971) studied this question.
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