Abstract

Brunser Patterns of spontaneous variation in heart rait; (HRV) in different frequency hands show continuous changes with advancing age These arc apparent m all S-W with specific trends for each type of HRV There is LI progressiv dominance of the sympathetic lone in active sleep and a predominant purasympathetic vagal tone in quiet sleep Thus, these patterns are not only related to the resulting balance of permanent competing sympathetic and parasvmpathetie controls but also are reliable indicators of CNS maturation in infants. In order to evaluate the effect of human milk (HM) on CNS dvelopment. we compare HRV patterns as a function of sleep-waking states in healthy breast-fed (Bf. n=16) and formula-fed (FF. n= 20) premature infants at 4 months corrected age (4.2+0.5 and 4.1 + 0.6, respectively). Polygraphic recordings were performed in the laboratory during the infant's spontaneous afternoon nap Four sleep-waking states (quiet sleep QS, paradoxical sleep:PS, indeterminate sleep IS, and waking W) were defined by combining electrophysiological and behavioral criteria Cardiac activity patterns RR interval. High, mid and low HRV, were evaluated by automated analyses Even though BF infants tended to show longer RR intervals in all S-W, these differences did not attain statistical significance HF infants presented higher amplitude of high- mid- and low-frequency HRV in AS, QS and W However, differences for high-frequency HRV during AS (p <03) and for mid-frequency HRV in QS (p < 05) reached significance. These suggestive tendencies of higher HRV in all S-W in BF infants, would indicate a more matuie pattern of CNS development in these infants This phenomenon is observed in all frequecy bands indicating thus, an effect in both sympathetic and para sympathetic systems The data support the statement that HM components (in the context of normal breast-feeding) critically favors the progression of CNS maturation Long-chain polyunsaturated fatty acids, present in HM, may be involved in this process.