The conduction system in patients with a prolonged QT interval.

The conduction system and the myocardium of five patients with Romano-Ward syndrome and one patient with the Jervell and Lange-Nielsen syndrome were studied to determine the cause of the prolonged QT interval. The patients were 9 and 15 months and 2, 5 and 19 years of age, respectively. All had a prolonged QTc interval. A sixth patient was a 16 year old girl who died suddenly; several members of her family had a prolonged QT interval. The only common finding in the conduction system in all cases was marked fatty infiltration in the approaches to the atrioventricular (AV) node. In four, the AV bundle was lobulated, with loop formation in one. In four, the AV bundle and bundle branches showed fibrosis. The ventricular myocardium in all cases was chronically inflamed. In two cases, the AV node was partially embedded in the central fibrous body. It is not clear how these changes are related to the disturbance in the repolarization process and the prolongation of the QT interval. However, it is interesting that all patients had an abnormality in the conduction system.