Age, waist circumference, and blood pressure are associated with skin microvascular flowmotion – The Maastricht Study

D.M.J. Muris, A.J.H.M. Houben, A.A. Kroon, R.M.A. Henry, C.J.H. van der Kallen, S.J.S. Sep, A. Koster, P.C. Dagnelie, M.T. Schram, C.D.A. Stehouwer

Background:
Skin microvascular flowmotion (SMF) – blood flow fluctuation attributed to the rhythmic contraction and dilation of arterioles – is thought to be an important component of the microcirculation, by ensuring optimal delivery of nutrients and oxygen to tissue and regulating local hydraulic resistance. There is some evidence that SMF is altered in obesity, T2DM, and hypertension. Nevertheless, most studies of SMF have been conducted in highly selected patient groups, and evidence how SMF relates to other cardiovascular risk factors is scarce. Therefore, we investigated which cardiovascular risk factors are associated with SMF in a population-based sample.

Methods:
We measured SMF in 506 participants of the Maastricht Study without prior cardiovascular disease. SMF was investigated using Fourier transform analysis of skin laser Doppler flowmetry at rest within five frequency intervals in the 0.01-1.6 Hz spectral range. The associations with SMF of the cardiovascular risk factors age, sex, waist circumference, total-to-HDL cholesterol, fasting plasma glucose, 24-h systolic blood pressure (SBP), and cigarette smoking were analyzed by use of multiple linear regression analysis.

Results:
Per 1SD higher age, waist circumference and 24-h SBP, SMF was 0.16 SD higher (95%CI: 0.07; 0.25; P<0.001), -0.14 SD lower (-0.25; -0.04; P=0.01), and 0.16 SD higher (0.07; 0.26; P<0.001), respectively, in fully adjusted analyses. We found no significant associations of sex, fasting plasma glucose levels, total-to-HDL cholesterol ratio, or pack years of smoking with SMF.

Conclusion:
Age and 24-h SBP are directly, and waist circumference is inversely associated with skin microvascular flowmotion in the general population. The exact mechanisms underlying these findings remain elusive. We hypothesize that flowmotion may be an important component of the microcirculation by ensuring optimal delivery of nutrients and oxygen to tissue and regulating local hydraulic resistance under physiological conditions, but also under pathophysiological conditions when microcirculatory perfusion is reduced, such as occurs with ageing and higher blood pressure. In addition, obesity may result in an impaired flowmotion with negative effects on the delivery of nutrients and oxygen to tissue and local hydraulic resistance.