Characteristics of atrio-His conduction in the short PR interval, normal QRS complex syndrome. Evidence for enhanced slow-pathway conduction

This study confirms the existence of accelerated conductionvia a fast atrio-His pathway in patients with the so-calledLown-Ganong-Levine (LGL) syndrome. Additional slow AH pathwayconduction was detected in about 50% of patients. Comparisonof slow pathway conduction characteristics in the LGL syndromewith AH conduction in age-matched normals and patients withdual AV nodal pathways revealed that the ‘slower’of dual AH pathways in LGL patients also exhibits relativelyenhanced conduction. This finding cannot be explained by thepresence of an anomalous AH pathway (‘James’ fibre')bypassing a normal A V node. It is suggested that a non-specificand as yet unknown effect causes enhanced conduction throughoutthe A V junction in patients with the LGL syndrome.