The Many Facets of Junctional Premature Complexes.

We present a case of a 60-year-old female patient, where the initial ECG showed a bradycardic rhythm due to early non-conducted P waves. The 24h-Holter analysis showed frequent junctional beats, dissociated from the P wave or with retrograde conduction, often related to early blocked P waves (in bigeminy or trigeminy) and periods of an apparent second-degree Mobitz II atrioventricular block (AVB). We believe that these Holter findings represent the main forms of presentation of junctional extrasystoles with varying types of conduction, including anterograde conduction and retrograde block, anterograde and retrograde conduction, anterograde block and retrograde conduction and anterograde and retrograde block, simulating Mobitz II second-degree AVB. The observation of these multiple forms of junctional extrasystole presentation in a 24h-Holter can help to better understand the behavior of junctional or Hisian premature beats and in the differential diagnosis with true second-degree AVB and blocked premature atrial contractions. [ABSTRACT FROM AUTHOR]