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June 1976

Lidocaine and His Bundle Extrasystoles: His Bundle Discharge Conducted Normally, Conducted With Functional Right or Left Bundle-Branch Block, or Blocked Entirely (Concealed)

Author Affiliations

From the Krannert Institute of Cardiology, Department of Medicine, Indiana University School of Medicine, and the Veterans Administration Hospital, Indianapolis. Dr Bonner is a Public Health Service trainee in cardiology.

Arch Intern Med. 1976;136(6):700-704. doi:10.1001/archinte.1976.03630060052011

Concealed discharge from the bundle of His was first postulated by Langendorf and Mehlman in 19471 to explain an unusual case of first- and second-degree atrioventricular (AV) block associated with junctional extrasystoles. Twenty-three years later, Rosen et al2 demonstrated the presence of concealed His bundle extrasystoles, and several subsequent reports have confirmed the observation.3-8

We present here another case demonstrating periods of PR prolongation and second-degree AV block mimicking types I and II, which resulted from concealed His bundle extrasystoles. The His bundle extrasystoles in this patient neither were coupled by a fixed interval to the previous QRS nor were they parasystolic; the His bundle extrasystoles either conducted normally, conducted with functional right bundle-branch block or functional left bundle-branch block, or blocked entirely, depending on the preceding cycle length and the coupling interval. These events afforded us a unique opportunity to study the effects of lidocaine on

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