Retarded heart growth in the victims of sudden infant death: possible implications for lethal mechanisms.

UNLABELLED: The study was aimed to compare the weight of the heart at death in infants who died of sudden infant death (SID) and in control infants under 1 year old. The study included 227 infants who died in St. Petersburg in 1983 to 1990 and who met the criteria of SID. One hundred and thirty-eight infants who died within 24 h out of hospital of defined respiratory infections within the same period of time constituted a control group. Infants with signs of malformations, tumours, and intrauterine infections were excluded from the study. A linear regression model was used in data analysis. No statistically significant association was found between the weight of the heart by the time of death and the following variables: gender, birth weight and length, ponderal index at birth, gestational age, calendar age at death, and length at death. Two variables which significantly influenced the heart weight and entered the linear regression model were infant's weight by the time of death and the cause of death (whether SID or not). No statistically significant interaction was found for these two parameters. It was found that each increase in total body weight by 1000 g brought with it an increase in the heart weight by 4 g (95% CI = 3.6-4.4); for the SID babies, the weight of the heart was less than for the control ones by 1.6 g (95% CI = 0.3-2.9 g).
CONCLUSION: Retarded heart growth may lead to functional disturbances and may contribute to possible mechanisms in some SID cases.