Significance of Mahaim fibers in crib death.

Crib death remains poorly understood both morphologically and functionally. The cardiac hypotheses postulating that crib death is due to lethal cardiac electrical instability is gathering a renewed interest. Aim of this work is to examine the likely role of Mahaim fibers in relation to crib death. We analyze 72 autopsied cases of crib death (47 male and 26 female infants, ranging in age from 3 to 365 days) and 24 age-matched controls. Mahaim fibers were found in 21% of crib death and in 8% of control cases. Mahaim fibers are specialized accessory pathways connecting the atrio-ventricular junction and the upper ventricular septum. These fibers, under particular conditions and/or neurovegetative stimuli, may cause pre-excitation and potentially malignant arrhythmias. The whole atrio-ventricular system or its junctional tract, can become part of a classical destabilizing circuit. Their possible role in pathogenesis of crib death will be discussed.