Cardiovascular pathology of Sudden Perinatal Unexpected Death (SPUD) and Sudden Infant Death Syndrome (SIDS)

Pathology of the cardiac conduction system can cause arrhythmias underlying SPUD and SIDS. A total of 38 SPUD and 130 SIDS victims were investigated. A complete autopsy was performed in each case, including in particular close examination of the cardiac conduction system, according to our guidelines. Accessory atrio-ventricular pathways, mainly Mahaim fibers, in 30% of cases; dispersion of His Bundle in 25% and cartilaginous meta-hyperplasia of the central fibrous body in 6% of cases were detected. The accessory fibers, in particular conditions and under autonomic neuronal stimulation, may underlie potentially lethal arrhythmias generally junctional reentrant in nature, being actually the most frequent in fetuses and newborns. In a total of 12 cases a fibromuscular hyperplasia of the pulmonary artery was detected. The fibromuscular hyperplasia of the pulmonary artery alone, might or might not have accounted for the sudden deaths, if it had not been for the concomitant presence of mild hypoplasia of the arcuate nucleus in the brainstem which could have had a triggering role in causing the sudden death. Of particular interest are borderline cases, which histological examination showed neoplastic lesions of the conduction system. The SPUD/SIDS «gray zone», or borderline cases, are described as those cases in which it is difficult to establish whether the pathological findings are sufficiently severe to have caused the death. Parental cigarette smoking is the most important risk factor for unexpected perinatal death and SIDS. Of interest were also the observation of early atherosclerotic plaques already detectable in fetuses and involving also of the sino-atrial and atrio-ventricular arteries.