Age-related characteristics of cardiointervalography and microcirculation parameters at different levels of urbanization

BACKGROUND: Age-related changes in autonomic regulation and microcirculation may be substantially modified by urban environmental factors; however, comparative analyses of these processes in settlements with different levels of urbanization remain insufficiently studied. AIM: The work aimed to assess the effect of age on spectral parameters of heart rate variability and microcirculation among residents of cities with different levels of urbanization. METHODS: Volunteers from three age groups (group 1, 18–44 years; group 2, 45–59 years; group 3, 60–74 years) permanently residing in a large city (Nizhny Novgorod), an industrial city with a developed chemical industry (Dzerzhinsk), and a small tourist city (Semenov) were examined. Heart rate variability was analyzed using the Poly-Spectrum hardware–software system (Neurosoft, Russia). Microcirculation was assessed by laser Doppler flowmetry (LAZMA analyzer, Russia). Statistical comparisons were performed using Student’s t test with Bonferroni correction. RESULTS: With increasing age, a decrease in total spectral power of heart rate variability (p 0.05) and individual spectral components was observed. Age-related changes in the heart rate variability spectrum were universal: the greatest increase in the contribution of the very low-frequency component was recorded at the age of 45–59 years among residents of the large city (by 66%), the industrial city (by 38%), and the small city (by 29%) compared with group 1, followed by an increase in high-frequency power at the age of 60–74 years: by 3-fold in large city residents, by 1.4-fold in industrial city residents, and by 1.6-fold in small city residents compared with group 2. However, a very low-frequency component was persistently elevated only among residents of the industrial city aged 60–74 years, exceeding that in group 1 by 21% (p 0.05). In microcirculation, aging was associated with a decrease in cardiac rhythm amplitude and an increase in endothelial rhythm amplitude across all groups. In individuals aged 60–74 years living in the large city and the industrial center, a reduction in myogenic rhythm amplitude was observed, whereas in the tourist city, this parameter demonstrated an opposite trend. CONCLUSION: The type of settlement influences universal age-related changes associated with a reduction in the activity of autonomic regulatory mechanisms as a whole. The greatest strain on regulatory systems was observed in middle-aged individuals (45–59 years), with subsequent persistence in older individuals (60–74 years) residing in an industrial center with a developed chemical industry, compared not only with residents of a small tourist city but also with those of a large city. These findings are relevant for the assessment of prenosological conditions and are important for the development of preventive public health measures.