[Familial sudden death in preexcitation syndrome. Surgical interruption of the anomalous pathways in two brothers (author's transl)].

We describe the results of surgical dissection of multiple accessory pathways in two brothers. A significant family history of pre-excitation syndrome was present: two children died suddenly and at the autopsy of one of them an accessory atrioventricular connection was found. In the first patient the preoperative electrophysiologic study showed anterior septal and posterior septal accessory pathways, and enhanced conduction in the A-V node. The second patient had the following anomalous connections: enhanced conduction in the A-V node; anterior septal, posterior septal and right lateral accessory pathways; Mahaim fiber. Intraoperative mapping, performed during pacing from different sites at different cycle length, was used to define the atrial and ventricular insertions of the accessory pathways as well as to confirm the surgical success.