1. RBBB pattern (rsR’ in v1 or qrS in v6).
  2. Initial part of the complex is similar to a sinus rhythm complex.
  3. Similar complexes seen earlier when patient was in sinus rhythm and then was clearly diagnosed as aberrant conduction.
  4. Complex ending a short RR interval after a long RR interval (preceding long RR- short RR sequence; second in a row phenomenon; Ashman phenomenon).
  5. The suspected complexes are all having preceding P waves.
  6. RBBB and LBBB patterns seen- more likely to be alternating BBB due to varying aberrancy rather than ventricular tachycardias from both ventricles.