Fractal scaling of laser Doppler flowmetry time series in patients with essential hypertension

Esen, Ferhan; Caglar, Saym; Ata, Necmi; Ulus, Taner; Birdane, Alparslan; Esen, Hamza

doi:10.1016/j.mvr.2011.07.012

Cited by 24 publications

(27 citation statements)

References 33 publications

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“…Although we found local lines with slopes equal to 1, these lines did not shift in parallel in both anatomical locations; volar region and gaiter area. These findings suggest that the local vascular functions are impaired in volar region and in gaiter area in EHT patients and are in agreement with the finding of existing literature (1)(2)(3)(4)(5)(6). Under pathological condition such as EHT, remodeling can eventually compromise vessel elasticity.…”

Section: Local Regionsupporting

confidence: 92%

“…For each region of every DFA graph, linear regression analysis was used to find the best fit line. Squared correlation coefficient, r 2 , and the p value for the best fit line were used to quantify the degree of linear association between Ln F n and Ln n. The slopes, scaling exponents, of these best fit lines can be used to evaluate the vascular/microvascular functions (1,20,26) and thus will be the focus of this study. The intercepts of best fit lines have no specific meaning for the cardiac and cardio-respiratory regions and we paid no attention to these parameters.…”

Section: Discussionmentioning

confidence: 99%

“…Studies (1,20) have shown that the value of cardio-respiratory scaling exponent is in the range of 1≥ α CR >0.5 for baseline LDF signal during supine rest in healthy young subjects and, vasodilatation decreases its value in the range of negative correlation, 0.5> α CRT >0. Because of the increased myogenic response due to increased pulsatility during vasodilatation, α CR is thought to reflect the coupling between central (cardiac and respiratory) and local mechanisms via a myogenic system.…”

Section: Cardio-respiratory Regionmentioning

confidence: 99%

“…Because of the increased myogenic response due to increased pulsatility during vasodilatation, α CR is thought to reflect the coupling between central (cardiac and respiratory) and local mechanisms via a myogenic system. Thus, the basal value of cardio-respiratory scaling exponent and its change in response to vasodilatation have been used to investigate the myogenic mechanism (1,26).…”

Section: Cardio-respiratory Regionmentioning

confidence: 99%

“…In the last two decade, studies on human cutaneous circulation have provided extensive data to assess microvascular function in a variety of vascular disease states including hypertension (1)(2)(3)(4)(5)(6). Although the skin blood flow measured from the volar region of the forearm has been commonly used to assess microvascular function in humans, the gaiter area (proximal to the medial malleolus) in the leg can also be used as an appropriate measurement site in some specific diseases.…”

Section: Introductionmentioning

confidence: 99%

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Comparative study of the upper and lower limb skin blood flow control mechanisms in patients with essential hypertension

Esen¹,

Ata²,

Esen³

2013

Anadolu Kardiyol Derg

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Objective: To investigate limb specific differences in cutaneous vascular function in patients (n=33) with essential hypertension (EHT). Methods: In this observational cross-sectional study, baseline skin blood flow and the response to local heating were measured with a laser Doppler flowmeter (LDF) from the volar region of the forearm and the gaiter area of the foot at supine rest. The fractal analysis, detrended fluctuation analysis (DFA), was used to calculate the correlation properties of skin blood flow, LDF signal. The paired t-test and repeated measures ANOVA were used to determine the response to local heating and compare the scaling exponents of different anatomical locations respectively. Results: We found three linear scaling regions that describe the fractal behavior of LDF signal with their slopes, scaling exponents. For cardiac (α C ) and cardio-respiratory (α CR ) scaling exponents, thermal hyperemia (T) induced greater change in the leg (α C =1.49±0.26; α CT =1.62±0.20 p<0.01 and α CR =0.84±0.29 α CRT =0.42±0.28 p<0.001) than in forearm (α C =1.28±0.13; α CT =1.33±0.13 p>0.05 and α CR =0.73±0.15; α CRT =0.65±0.018 p<0.05). Local scaling exponents (α L ≈α LT~1 ) were not significantly different (p>0.05) and, local lines did not shift in parallel with local heating in both extremities. Conclusion:The results of the present study suggest that skin microvascular function is impaired in both extremities in EHT patients. However, myogenic response is not uniform in both extremities and pronounced response to local thermal hyperemia has been observed in the gaiter area compared with the volar region. Further studies are needed to determine if these limb specific microvascular differences is the result of posture-induced structural and functional adaptation. (Anadolu Kardiyol Derg 2014; 14: 3-8)

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