Detection of masked hypertension based on laser Doppler flowmeter measurements
Masked arterial hypertension (MAH) is one of the phenotypes of arterial hypertension (AH) associated with target organ damage and the development of cardiovascular complications, which are one of the leading causes of disability and mortality in the Russian population. The disease is asymptomatic and characterized by an average level of BP at the doctor's office, which determines the difficulties of diagnosing MAH. Currently, the only methods for diagnosing MAH are home BP monitoring (HBPM) and ambulatory BP monitoring (ABPM). Thus, one of the most important tasks of health care is to reduce cardiovascular risk by developing and implementing in clinical practice affordable and straightforward methods for diagnosing hidden increases in BP during dispensary observation of the population. The purpose of this work was to evaluate the possibility of using the laser Doppler flowmetry (LDF) method for the detection of masked hypertension.
The study included 80 men aged 30 to 60 years (46 ± 8) who subjectively considered themselves healthy, did not make any complaints and did not take any medications regularly. All subjects underwent LDF blood perfusion measurements on the left forearm and ABPM after the physical examination. The participants were divided into three groups according to the recommendations of the European Society of Cardiology, depending on the office BP and SBPM indicators. Group 1 included 29 men with normal BP (46 ± 8); group 2 included 27 men with MAH (45 ± 9); 24 men were in the 3rd group with a persistent increased BP (48 ± 11).
Index of microcirculatory (Im) does not differ significantly between the groups, but there is an unreliable trend to reduce skin perfusion in the MAH group relative to group 1 – 3.09 and 3.69 (p=0.078). When analyzing the amplitude of vasomotion of tone-forming mechanisms (Ai), which reflect the vasomotor activity of resistive arterioles, there is an unreliable trend towards increasing the amplitude of endothelial vasomotion in the MAH group in comparison with the normotonic group – 0.2 and 0.16 (p=0.093). Neurogenic amplitude vasomotions significantly lower in the group with AH relative to the MAH - 0.13 and 0.2 (p«0.05). The amplitudes of myogenic oscillations between the groups were not significantly different. Passive mechanisms (respiratory, pulse) also showed no significant differences. Significant increase in the contribution of endothelial oscillation is noted. When a vasomotor activity is normalized to the perfusion level (Ai/Im×100%), which reflects the contribution of the blood flow modulation mechanism to tissue perfusion, there is a significant increase in the contribution of the endothelial vasomotion mechanism to tissue perfusion (Ae/Im×100%) in the MAH group relative to group 1 and 3 – 5.82, 4.32 and 3.7, respectively (p«0.05). The contribution of pulse fluctuations (Ac/Im×100%) to tissue perfusion is significantly higher in subjects of groups 2 and 3 relative to the control group – 8.89, 8.64 and 7.0 (p«0.05). There were no significant differences in the perfusion contribution of the other mechanisms.
In patients with MAH, the increase in the amplitude of endothelial vasomotions is presumably compensatory, aimed at maintaining tissue homeostasis against the background of reduced tissue perfusion. An increase in the contribution of pulse fluctuations in both groups of hypertensive patients may be associated with an increase in the level of BP (the rate of propagation of the pulse wave).
The LDF method can be a useful tool for deciding on further investigation for the presence of a hidden increase in BP, which requires subsequent comprehensive research.
This work was supported by the Russian Foundation for Basic Research (RFBR), grant 20-08-01153А.
Yulia I. Loktionova
Research and Development Center of Biomedical Photonics, Orel State University named after I.S. Turgenev
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