RESUMO
OBJECTIVE: The scope of this study is to detect whether or not the entropy (E) circadian rhythm (CR) is maintained preserved in sinusal R-R intervals (SRRI), its loss being the expression of a transition to an indeterministic chaos in heart rate variability (HRV). METHODS: The E of SRRI was estimated in 14 type I diabetic pregnant women (DPW) in the first trimester of an apparently uncomplicated gestation (7 patients - mean age = 30.3 +/- 4.1 y - without clinical and laboratory evidence of cardiac autonomic neuropathy, and 7 patients - mean age = 30.7 +/- 3.6 y - with positive tests for a cardiac dysautonomia). The E CR was studied via the single cosinor method, and summarized via the population-mean cosinor method. RESULTS: The E CR was found not to be preserved in both the investigated type I DPW, despite the occurrence of the SRRI CR. CONCLUSIONS: The loss of the E CR confirms that in type I DPW there is a transition to an indeterministic disorder in HRV due to the lack of an autocorrelated periodic chaos in cardiac pacing. Such an unphysiological neurovegetative regulation suggests a new silent cardiac dysautonomic syndrome, that we intend to call "minimum delirium cordis syndrome" (MDCS). Can the MDCS be regarded as a condition of cardiovascular risk? To answer this question, it seems justified to suggest that the study of the E CR should be added to the routine tests that are presently applied to clinical analysis of the Holter ECG, being the classic tests of linear analysis not methodologically suitable for detecting the indeterministic chaos of the MDCS.
