[Bundle of His extrasystoles as a cause for A-V block and junctional tachycardia (author's transl)].

The electrophysiological findings in two cases with premature beats arising from the bundle of His are presented. In the first case, the nonconducted impulses led to a functional first and second degree A-V block of the following sinus beats due to retrograde concealed conduction. In addition, very early premature beats from the bundle of His were conducted retrogradely to the atrium simulating blocked premature atrial beats. In the second patient, the premature beats appeared as bigeminy after each sinus beat. As the sinus beats and the extrasystoles from the bundle of His showed a left bundle branch block pattern, a ventricular tachycardia was suspected from the findings in the surface ECG. The reported cases demonstrate the clinical value of the His bundle electrography in patients with bradycardic and tachycardic rhythm disturbances.