[The autonomic nervous system in sudden infant death syndrome. Analysis of heart rate and sinusal variability on Holter monitoring of infants who died].

To evidence abnormality of cardiac control by the autonomic nervous system in the sudden infant death syndrome (SIDS) we retrospectively analysed the Holter recordings and cardiopneumograms of 19 infants (11 boys, 8 girls) of mean +/- SD age 2.3 +/- 1.5 months who had subsequently died of SIDS. Two infants were regarded as normal and the reference diagnoses in the remaining 17 infants were: apparent life threatening event (8), SIDS siblings (8) and prematurity (1). At the time of death the age was 4.2 +/- 2 months. Each of these infants was matched with three control infants in term of postnatal age, gestational age and reference diagnosis, but without SIDS at follow-up of at least one year. Nine hours of Holter recordings (9 p.m. to 6 a.m.) were analysed in term of mean heart rate and sinus oscillations waves. To differentiate between short oscillations of 4 to 6 RR, which are induced by respiration and reflect vagal activity, and long oscillations of 20 to 32 RR, which reflect both neurogenic sympathetic and vagal activity, we used a new method which measures the number and the amplitude in milliseconds of each type of oscillations. The results are expressed as the logarithm of the product of these two variables. Heart rate, correlated to age in both groups, is higher in the deceased infants group (141 +/- 14 mn and 135 +/- 15; p less than 0.05: analysis of covariance with age as an independent variable). Short oscillations, also correlated to age, are lower in the deceased infants group (3.35 +/- 0.59 and 3.65 +/- 0.61; p less than 0.05: analysis of covariance with age).(ABSTRACT TRUNCATED AT 250 WORDS)