The sinus node in sudden infant death syndrome.

The sinus node (SN) was examined histologically in 30 infants diagnosed with sudden infant death syndrome (SIDS) and in 18 age-matched controls who died of known causes. Location, size and organization of the SN did not differ significantly in the two groups Petechiae involved the SN region in 20% of SIDS and 17% of control infants and probably do not represent a primary event. In three SIDS infants (10%), intimal lesions reduced the lumen of the intranodal SN artery by 63-83% in cross-sectional area. These resembled the intimal thickenings frequently observed in main epicardial coronary arteries of infants. Whether the vascular alterations in these three cases had adverse effects upon SN function is unknown.