FEATURES OF HAEMOSTASIS IN DIFFERENT TYPES OF 24 HOURS DAY'S PROFILE OF BLOOD PRESSURE IN HYPERTENSIVE PATIENTS OF DIFFERENT AGE GROUPS

Abstract

Relevance. The phenomenon of non-dipper (insufficient nocturnal decrease in blood pressure) has prognostic significance for increasing the risk of complications of arterial hypertension - myocardial infarction, stroke. To date, there are only isolated reports of platelet hemostasis in this category of individuals. Therefore, it is important to find out the peculiarities of state of platelet aggregation depending on circadian rhythm of blood pressure (BP).
 Objective is to identify the baseline level of platelet and plasma hemostasis at different 24 hours day's blood pressure profiles in middle-aged and elderly hypertensive patients.
 Materials and methods. Subjects (n=90) are divided into 3 groups. Group 1 (n=30) included middle-aged hypertensive patients (45-59 years), group 2 (n=30) − elderly hypertensive (60-74 years) patients. Patients are divided into two subgroups in each of these groups, 15 people in each: subgroup dipper (D) − with adequate nocturnal blood pressure reduction (10-20 %) and subgroup non-dipper (ND) − with insufficient nocturnal blood pressure reduction (<10 %). The control group (n = 30) consisted of 15 patients without arterial hypertension for each of the examined groups. 
 The state of spontaneous and induced platelet aggregation was determined. Adenosine diphosphate (1´10-5 mM/L) and adrenaline (1 µg/mL) were used as aggregation inducers on SOLAR AP-2110 optical aggregometer. The following parameters of aggregatograms were calculated: amplitude of spontaneous and induced aggregation (AA, %); time of maximal aggregation (TMA, min.); slope of aggregation (SA, %/min.). The state of plasma hemostasis was determined on hemocoagulometer Amelung KC 1A. The following parameters were determined to assess state of plasma hemostasis: fibrinogen (FG, g/L), antithrombin III (AT-III, %), fibrinolysis (min.).
 Results. The increase in induced platelet aggregation activity was found in middle-aged hypertensive patients. In subgroup D AA was 1,9 times and in subgroup ND – 2,3 times higher than the norm; the rate of SA increased by 105,5 % and 112 %, respectively. In subgroup ND compared with subgroup D AA was higher by 21 % and SA − by 3,2 %.
 In elderly hypertensive patients, the rate of spontaneous aggregation AA is 1,7 times higher in subgroup ND compared with subgroup D (4,2±1,6 % vs. 2,5±0,2 %). In the ND subgroup AA rate is 68 % higher than in the control. Indicators of induced platelet aggregation were also higher in subgroup ND compared with subgroup D: AA with induction of ADP – 74,7±25,1 % vs. 51,4±22,2 %; TMA with adrenaline induction – 8,2±2,6 minutes against 5,7±2,5 minutes, respectively. There was the significant reduction in TMA with adrenaline-induced aggregation by 30,5 % in subgroup D compared with the control also.
 Fibrinolysis activity in middle-aged hypertensive patients in subgroup D was slowed down by 36,1% compared with the control group: fibrinolysis was 215,0±49,7 minutes while 158,0±5,7 minutes in the control group.
 Conclusions. Platelet hemostasis changes with age in the direction of increasing the aggregation properties of platelets in hypertensive patients. More pronounced changes were found in patients with insufficient reduction of blood pressure at night. In elderly patients, the most significant changes are determined by adrenaline-induced aggregation compared with middle-aged patients.