Morphometrical investigations into alterations of the wall thickness of small pulmonary arteries after birth and in cases of sudden infant death syndrome (SIDS).

In 1973 Naeye was the first to demonstrate that, in cases of SIDS, the small pulmonary arteries have more smooth muscle than in controls and suggested that this is a consequence of chronic alveolar hypoxia. Seventy-five cases have been investigated morphometrically in order to obtain quantitative data on the alterations of wall thickness of the small pulmonary arteries after birth and in cases of SIDS. The investigations comprise seven cases of stillbirth, 19 cases of newborn, 33 cases of SIDS and 16 controls. In each case the thickness of the media, the external diameter of the artery and the media area have been measured planimetrically for 90 arteries ranging between 50 microns and 500 microns. A media index was calculated as the ratio of the thickness of the media to the diameter of the artery. Using this index a thickening of the media of the small pulmonary arteries, corresponding to the situation in fetal and neonatal life, has been confirmed for cases of SIDS. The normal postnatal changes in the small pulmonary arteries, media thinning and enlargement of the lumen, could not be observed in SIDS cases in the first year of life.