Beat-to-beat heart rate (HR) and blood pressure were measured by the Finapres system in 44 healthy and 64 diabetic subjects in the at-rest condition. Autonomic control in diabetic subjects was assessed by the Ewing test. HR variability was explored by both linear and nonlinear methods. Linear methods used HR standard deviation and power spectrum. The percentage of the spectrum in the low frequencies was used to assess the sympathetic tone of the autonomic control. The nonlinear method used the "recurrence plot." This method explored long parallel subsequences in the HR time series. These sequences characterize the dependence of the HR dynamics on initial values. The HR standard deviation was reduced in the diabetic subjects compared with the healthy subjects (2.80 +/- 1.17 vs. 3.64 +/- 1.45 beats/min; P < 0.001). In the diabetic subjects, the HR standard deviation and the percentage of the spectrum in the low frequencies showed no correlations with the Ewing score (P > 0.10). In contrast, the longest length index was very strongly correlated to the Ewing score (r = -0.60; P < 0.0001). The results suggest that nonlinear methods might be powerful to explore the autonomic dysfunction in diabetic subjects.
PhagocytosisOxidative burst suggesting a synergistic effect by adding tetracycline (2 g/d) [1, 4], there have been no controlled studies comparing the efficacy agents.
Beat-to-beat heart rate (HR) and blood pressure (BP) were measured by the Finapres system in 28 healthy subjects and 64 diabetic subjects. Autonomic controls in diabetic subjects were assessed by scoring 5 cardiovascular function tests (high score = abnormal control). The fractal dimension (FD) of HR (or SBP) was estimated as follows: Measuring the curve of 500 successive HRs with a rule of length L, one obtains N times L. The FD is the slope of the regression line of Log(N) versus Log(1/L) for different L. We found a lower FD of HR in diabetic subjects than in healthy subjects (1.35 +/- 0.10/1.44 +/- 0.09, p = 0.0002) and a similar FD of SBP in the 2 groups. In diabetic subjects, the FD of HR was negatively correlated with age (r = -0.27, p = 0.03), duration of diabetes (r = -0.33, p = 0.0078) and score of disautonomy (r = -0.43, p = 0.0007). So, heartbeat is more fractal in healthy status: a low fractal fluctuation is a sign of pathology.
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