Not All Sore Thumbs Are Ventricular In Origin-KH

Frank Yanowitz Copyright 1996

PAC's have three fates: normal conduction into ventricles, aberrant conduction in ventricles due to bundle branch or fasicular block, and non-conduction due to block in AV junction. In this example PAC '1' is normally conducted and PAC '2' is conducted with RBBB aberration. The longer preceding cycle increases the refractory period in the right bundle.