[The rhythms of arterial pressure and heart rate in individuals with arterial hypertension under the conditions of Far North].

The circadian and ultradian rhythms of blood pressure (BP) and heart rate (HR) were studied by means of 24-hour BP monitoring in patients with arterial hypertension (AH) and practically healthy people working in Far North shifts. The subjects were 418 men. The main group consisted of 177 men aged 18 to 59 working in trans-polar shifts in Yamburg, Tyumen region, latitude 57 North. The comparison group included 158 residents of a moderate climatic zone (Tyumen, latitude 57 North). The control group consisted of 83 practically healthy men, of whom 43 worked in Far North shifts, and 40 were residents of Tyumen. The groups were comparable by age, AH duration, and office systolic and diastolic BP (SBP; DBP). The study demonstrates that even healthy people working in Far North shifts display high BP variability and the decrease of the stability and power of SBP, DBP and HR circadian rhythms due to the reduction of the amplitude, contribution of the rhythm to the total variability, and the increase of the amplitude of high-frequency harmonics of the spectrum (a manifestation of extracircadian dissemination), which may be a sign of accelerated ageing and biological age increase, and may facilitate AH development. Development of AH under the extreme conditions of Far North shifts, unlike the conditions of moderate climatic zones, is accompanied by progressive BH variability increase, the worsening of the chronological structure of SBP and DBP, the increase of extracircadian dissemination, which can be of both clinical and prognostic significance.