Features of cerebral autoregulation and reactivity in patients with arterial hypertension in older age groups with orthostatic hypotensive reactions
Authors: Atyunina I. V. , Oshchepkova E. V. , Rogoza A. N. 
Published: February 2021

Aim. To study the condition of cerebrovascular autoregulation and reactivity in different variants of orthostatic hypotensive reactions (OНR) in elderly patients with hypertension (АН).
Materials and methods. 50 patients with AH were examined (80% of women) aged 60 to 82 years (68.55.3). The duration of hypertension is from 2 to 43 years (16.811.6 years).The daily blood pressure profile was evaluated by the method of daily monitoring of blood pressure (BPLab, Russia). A study of OНR was carried out using an active orthostatic test (AOP) with continuous monitoring of cerebral blood flow (CBF) and with a minute measurement of blood pressure by the oscillometric method and continuous non-invasive measurement of SBP (systolic blood pressure) and DBP (diastolic blood pressure) in the finger artery (Task Force Monitor CNSystems Austria). The CBF velocity in the middle cerebral artery (SMA) was estimated using a transcranial sensor with a frequency of 2 MHz on an Angiodin-2K ultrasound machine (BIOSS company, Russia). In SMA, systolic (Vs), diastolic (Vd), average cerebral blood flow velocity ACBF (Vm), pulsation index (Pi), and vascular resistance index (Ri) were recorded. The difference between the indicators was calculated initially and during AOP (in the first 30 seconds and for 3 minutes): Vm30s, %, Vm3m, %. Reactivity was assessed using a hypercapnic test (HCP) with breath holding. The relative change in the CBF indicators in the MCA was calculated by the formula: Kr = (Vm1Vm2)100%/Vm1, where Kr is the reactivity coefficient, Vm1 ACBF at rest; Vm2 ACBF during the test. Statistical analysis was performed using the non-parametric MannWhitney method using Statistica 6.0.
Results. In 17 (34%) patients with AH, OGR was detected. In 6 (12%) examined patients, initial OHR (IOH) was detected, in 6 (12%) classic OHR (COH), in 5 (10%) there was a combination of COH+IOH. According to the ABPM data, in patients with OHR compared with patients without OHR, there were no significant differences in the daily level of blood pressure (mmHg), SBP: 131.712.2 vs 131.313.8, p0.05; DBP 74.311.8 vs 75.38.9, p0.05). In AOP, patients with OHR significantly decreased Vm in orthostasis compared with patients without OHR, both in the first30 seconds and at 3 minutes (Vm30s: 25.05.5 vs 30.44.7, p0.05; Vm3m: 27.05.2 vs 31.24.7, p0.05; Vm30s,%: 17.06.5 vs 8.34, 1, p0.05; Vm3m,%: 11.76.3 vs 5.82.4, p0.05). When performing HCТ between patients with OHR and without OHR, statistically significant differences in the indices Pi (0.790.08 vs 0.780.16, p0.05) and Ri (0.510.09 vs 0.530.07, p0.05) was not detected, however, in patients with OHR there is a tendency to a less pronounced increase in АCBF at the peak of HCT compared with patients without OHR (36.86.4 vs 40, 06.6, p=0.13). In patients with OHR, the cerebral reactivity coefficient was lower than in patients without OHR (13.43.9 vs 20.76.6, p0.05).
Conclusions. In patients with AH of older age groups with OHR, a statistically significant decrease in ACBF in orthostasis was revealed. Patients with IOH showed a decrease in ACBF in the first seconds of orthostasis with its subsequent stabilization. Persons with COH have preserved the mechanisms of cerebral autoregulation in the first seconds of orthostasis, but with prolonged orthostatic load (3 minutes), the effectiveness of autoregulatory mechanisms decreases. OHR in patients with hypertension of older age groups is associated with a decrease in cerebral reactivity.