Concealed (proximal) Wenckebach phenomenon with distal 2:1 exit block in the ectopic-ventricular junction

The findings in two patients with interpolated ventricular extrasystoles showing 2:1 exit block are reported. In these patients the blocked impulses appear to penetrate into the ectopic-ventricular junction (or reentrant pathway) to a varying extent, and the coexistance of a distal 2:1 exit block and a proximal (concealed) Wenckebach phenomenon in the ectopic-ventricular junction is suggested.