Background: Fractal analysis has been shown to be capable of characterizing irregular time
series generated in non-linear systems. Fluctuations in skin flow signals have a fractal nature,
but to date there has been no analysis of subjects with hypertension. The aim of this study is to
assess the fractal dimensions of skin microcirculation flows in subjects with a familial predisposition
or newly diagnosed hypertension.
Methods: A four-minutes rest flow (RF), minimal flow (BZ) during three-minutes ischemia
and eight-minutes heat flow (HF) were recorded (using laser Doppler flowmetry) in patients
with untreated hypertension, and in normotensives with no [NT(-)] or with a familial predisposition
to hypertension [NT(+)]. Average one-minute surface areas under the curve of flow
records and box dimensions (D) were calculated. Anova Kruskall-Wallis, c2 statistic and
multivariate reverse regression analysis were used for calculation.
Results: We studied 70 people (average age 36.1 ± 10.3 years, 39 men). Hypertensives (n = 31)
had significantly higher values of both clinical blood pressure and 24-hour ambulatory blood
pressure, body mass index, glucose, triglycerides and insulin than the NT(-), (n = 17) and
NT(+), (n = 22) groups. Mean values of flows and surface area under the curve of RF, BZ,
HF records, D RF and D HF were comparable in studied groups, but D BZ differed (1.13 ±
± 0.05 vs 1.15 ± 0.05 vs 1.11 ± 0.05, respectively; p = 0.04). A family history of hypertension,
insulin level and variability of 24-hour diastolic blood pressure were significant predictors of
D BZ lower values in the multiple regression model.
Conclusions: Subjects with a familial predisposition to hypertension reveal altered homeodynamics
of microvascular flow, with diminished chaotic ischemic flow. (Cardiol J 2011; 18,
1: 26-32