[Importance of PQ time in the evaluation of bifascicular block]

In 103 patients with bifascicular block was tested by means of the His bundle electrography, whether with the help of the PQ-time an indirect estimation of the conduction capacity of the still conducting fascicle (HV-interval) is possible. In 70% of the cases with bifascicular blocking and AV-block of first degree the HV-interval was prolonged. However, also 45% of the patients with bifascicular block showed a prolonged HV-interval despite normal PQ-time. Of 21 patients with syncopes due to an intermitting trifascicular block 10 had a normal PQ-time in phases of the transduction. Thus a normal PQ-time in patients with bifascicular block is no guarantee for a good transduction via the still conducting fascicle. If in patients with bifascicular block additionally an AV-block of first degree is existing, the place of the primary retardation of the conduction should more exactly be analysed. For this purpose offer themselves an atropine test or the His bundle electrography.