| Abstract: | Some intra-His bundle (intra-HB) blocks escape the routine exploration of the His bundle and are confused with supra- or infrahisian blocks. We believe that a more accurate exploration (recording of His bundle activity successively at the proximal end and the distal end of the His bundle, dynamic tests and drug injection) is needed to detect some concealed cases, mostly paroxysmal intra-HB blocks. In this series of 102 cases of intra-HB blocks, 20% had no criteria of AV block on the surface electrocardiogram, and only 4% had an intact conduction pattern (normal PR interval and normal QRS complexes.) A first degree intra-HB block was found in 35% (15 cases with a normal PR interval), a second degree intra-HB block in 23% and a thired degree intra-HB block in 42% of the cases (unidirectional in 4 cases). Of the 43% having an isolated intra-HB block, most were elderly women with a chronic third degree AV block. |
