[Sudden infant death syndrome. A case with accessory atrio-ventricular pathways and fetal ring tissue remnants].

A 55 day-old male infant dying suddenly is diagnosed as sudden infant death syndrome (SIDS). Important modifications of the cardiac conduction system were found; such as: splitting-His bundle dispersion, accessory atrioventricular pathways of Mahaim type, and remnants of fetal "ring tissue" anastomosing with ordinary myocardium. These changes can be considered as arrhythmogenic in nature.