[Short PR-normal QRS syndrome, pre-excitation syndrome or a variant of normal conduction?].
An electrophysiological exploration was carried out in 48 patients presenting a syndrome short PR-small QRS (group I), compared to a reference group of 537 patients who did not present this abnormality and had no previous history of Bouveret's tachycardia (group II). The most remarkable abnormality in group I is an acceleration of the anterograde nodal conduction with a Wenckebach point beyond 200/min, significantly more frequent than in group II. The retrograde conduction is also excellent in group I, but without significant difference in comparison to patients from group II who have an accelerated anterograde conduction. The risk of triggering a supraventricular tachycardia is not statistically more important in group I than in group II. However, an accelerated nodal conduction presents an increased risk of triggering a supraventricular tachycardia, in group I as well as in group II. It is therefore concluded that the syndrome short PR-small QRS is, in the large majority of cases, only an aspect of the syndrome of accelerated nodal conduction, a variant of normal conduction. It is only in a few rare observations that it can be ascribed to the probable presence of pre-excitation fibers: 2 cases out of 48 in this series.