Fractal dimension of heart rate and blood pressure in healthy subjects and in diabetic subjects.
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.
Chau
N P
NP
URBB, INSERM U263, Université Paris, France.
Chanudet
X
X
Bauduceau
B
B
Gautier
D
D
Larroque
P
P
D000328:Adult; D000368:Aged; D001342:Autonomic Nervous System Diseases / Q000503:physiopathology; D001794:Blood Pressure / Q000502:physiology*; D003920:Diabetes Mellitus / Q000503:physiopathology*; D003929:Diabetic Neuropathies / Q000503:physiopathology; D005260:Female; D017709:Fractals; D006334:Heart Function Tests; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values