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10THE GESTATIONAL PROCESS IN PREGNANT WOMEN WITH DISORDERS OF THE HEART RATE VARIABILITY
Kaminskyy Vyacheslav, MD, Head of Department Tkachuk Roma, researcher
Kyiv, Ukraine.
National Medical Academy of Postgraduate Education named after P. L. Shupyk DOI: https://doi.org/10.31435/rsglobal_ws/12072018/6033
ABSTRACT
Aim of the study: To analyze the pregnancy course in women with the autonomic regulation dysfunction, diagnosed by cardiointervalography and heart rate variability changes.
Materials and methods. 102 pregnant women were examined. The initial autonomic status was estimated by registration of time and spectral parameters of heart rate variability applying the computer cardiointervalography and CardioLab BabyCard diagnostic system. The I (main) group consisted of 48 pregnant women with established disorders of autonomous regulation. 54 patients with a normal state of autonomic supply, a balanced level of sympathetic and parasympathetic activity and an optimal level of regulatory systems functioning formed a II (control) group. To assess the condition of the mother-placenta-fetus system an ultrasound examination with doplerometry was performed. Results. Heart rate variability has established a significant increase of central regulatory circuit activity in pregnant women with autonomic dysfunction. Hyperfunction of the sympathetic department in women of the main group was accompanied by exhaustion of compensatory vagal influences. The obtained values of VLF testify about the psycho-emotional stress and cerebral cortex functional disorders existence in these women. Cardiointervalography data in the control group indicate for a balanced activity of the autonomic nervous system. The complications of pregnancy were significantly more frequent in women of the main group in the context of detected autonomic dysfunction. Conclusions. Cardiointervalography is informative for the detection of autonomic regulation disorders, adaptive disorders and changes of hemodynamic responses in mother-placenta-fetus system. Using the analysis of heart rate variability in pregnant women will improve the early prediction of gestational pathology, reduce the risk of obstetric and perinatal complications.
Citation: Kaminskyy Vyacheslav, Tkachuk Roma. (2018) The Gestational Process in Pregnant Women with Disorders of the Heart Rate Variability. World Science. 7(35), Vol.4. doi: 10.31435/rsglobal_ws/12072018/6033
Copyright: © 2018 Kaminskyy Vyacheslav, Tkachuk Roma. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
ARTICLE INFO
Received: 12 May 2018 Accepted: 28 June 2018 Published: 12 July 2018
KEYWORDS
autonomic nervous system, sympathetic nervous system, pregnant women
Introduction. The gestational period is associated with dynamic changes in the autonomic nervous system (ANS). During normal pregnancy the activity of the sympathetic part goes up in the first trimester, progressively increases in II and III trimesters and decreases before delivery. The
increasing tone of the sympathetic nervous system (SNS) is an adaptive mechanism that is developing in response to peripheral vasodilatation and prevents excessive reduction of systemic blood pressure.
Parasympathetic and sympathetic parts of the ANS are constantly interacting and are under the influence of a number of reflexory and humoral factors controlled by the central nervous system. The dysfunction of the ANS, pathological changes in the vascular tone regulation and the status of cerebral blood flow may damage the "mother-placenta-fetus" functional system and lead to the gestation complications development [1].
The "language", that conveys information about the energetic and regulatory processes of the mother and fetus is the heart rate variability. Fluctuations in the blood circulation system are caused by energetic (metabolic), humoral and autonomic processes and reflect their condition [2].
Investigating the mother and fetus heart rate variability will provide an information about the energy supply, humoral and nervous regulation, their changes during stress and other conditions, about the adaptive capacity and mother-placenta-fetus system reserves [3,4].
Currently, the state of gravidar homeostasis by the analysis of mother and fetus heart rate variability in comparison with the morphological structure of the placenta in physiological pregnancy, preeclampsia of various severity, under placental insufficiency, under intrauterine infection, underweight, premature deliveries and other pregnancy complications has been studied [5-17].
It is shown that mathematical, time and spectral analysis of mother and fetus heart rate variability provides information about the energy supply system (normal, energy deficit, energy crisis); about the components of general regulation (metabolic, sympatho-adrenal, parasimpatical); about the ratio of the central and autonomic contours of heart rate regulation; about adaptation reserves (normadation, hyperadaptation, hipoadaptation, energy fold and functional rigidity) [18].
Thus, the study of heart rate variability of the mother and fetus can widely be used to assess gravidar homeostasis in physiological and pathological pregnancy, can allow us to reinterpret the nature of the processes occurring in the "pregnant woman" system, open up a fundamentally new approach to the prognosis and prevention of obstetric and perinatal complications [19].
The aim of this study is the analysis of pregnancy in women with the autonomic regulation dysfunction, diagnosed by cardiointervalography and heart rate variability changes.
Materials and methods. 102 pregnant women who were undergoing treatment in the Obstetric Department of Kiev City Center of Reproductive and Perinatal Medicine, which is the clinical site of the Obstetrics, Gynecology and Reproductology Department of the Ukrainian State Reproductology Institute of the National Medical Academy of postgraduate education named after P. L.Shupyk had been surveyed during the study.
All the surveyed women have undergone general clinical and special obstetric examination in accordance with the diagnostic and treatment protocols approved by the Ministry of Health of Ukraine. All studies were performed only after obtaining informed consent of the patient to be the part of additional research methods.
The pregnant women with fetal malformations, patients with multiple pregnancies, endocrine disorders, severe extra-genital pathology, internal reproductive organs malformations, benign tumors of the female reproductive system, etc were excluded from the research. Also in the course of study the pregnant women who had indications for planned surgery delivery were excluded from the test group.
The average age of pregnant women was 28.3 ± 5.8 years. In a registered marriage were 75 (73.5%) pregnant women, in the civil - 23 (22,5%), single - 4 (4%) women.
The prevalence of somatic pathology is the following: the respiratory system - in 8 (7,8%) women, cardiovascular system - in 36 (35,3%) pregnant women, endocrinopathy - in 29 patients (28,4%), pathology of the urinary system - in 33 (32,4%), gastrointestinal tract disorders - in 11 (10,8%) pregnant women, liver and biliary tract dysfunction - in 12 (11,8%) women, blood system diseases - in 21 (20,6%) patients, eye diseases - in 35 (34.3%) pregnant women, venous varix dilatation - in 9 (8,8%) of surveyed.
The average number of pregnancies among the surveyed categories was 2.4 ± 0,14. Primigravidas were 56.9% or 58 women. Preterm delivery in anamnesis had 9 (8.8 %) of pregnant women. 1 or 2 medical abortions had 40 women (39,2%), 3 or more abortions - 6 (5,9%) patients, spontaneous abortions were observed in 26 (25.5 %) of the surveyed, missed miscarriage - in 15 (14,7%) pregnant women. Inflammatory diseases of the pelvic organs were detected in 33 (32.4%) women, sexually transmitted infections - in 42 (41,2%) patients, uterine leiomyoma was diagnosed in 14 (13.7%) of pregnant women, ovarian cysts - in 3 (2,9%) patients, endometriosis - in 8 (7,8%) women, cervical pathology - in 19 (18,6%) pregnant women. Menstrual cycle disorders were noted in 28 (27,5%) patients.
According to the results of previous studies of heart rate variability 2 groups of pregnant women have been defined:
1 - the main group of 48 pregnant women with diagnosed autonomic disorders, characterized by autonomic imbalance, signs of stress and centralization of regulatory systems.
2 - the control group of 54 patients - with normal autonomic supply, balanced sympathetic and parasympathetic activity, the optimum level of regulatory systems functioning and the prevalence of the autonomous influences on the regulation of gestational homeostasis.
Randomized approach was used during sample selection. Verification of the groups homogeneity confirmed the absence of significant differences. The studied groups were of the identical by age, gestational age and parity births.
Evaluation of initial autonomic status was carried out by registration of time and spectral parameters of heart rate variability (HRV) by the computer cardiointervalography (CIG). The medical diagnostic system "CardioLab BabyCard" ("KhAI Medica", Kharkiv, Ukraine) was used for CIG. The built-in system indicators were taken into account during analyzing the results of the research.
The following time indicators were registered:
1. SDNN, ms - the mean square deviation of successive RR intervals, the indicator of the total effect of autonomic regulation of blood circulation, reflects the overall ANS tone;
2. pNN50,% - the number of consecutive RR intervals that differ by more than 50 ms during the recording period is considered as a measure of the benefits of the parasympathetic control over the sympathetic;
3. Mode amplitude (MoA),% - RR-intervals fraction of the analyzed time series corresponding to the value of the mode, the indicator of the activity of the sympathetic level of regulation;
4. Variation velocity (VAR), ms - difference between the duration of the largest and the smallest RR interval of the analyzed time series, conditional parameter of activity of the parasympathetic nervous system (PNS);
5. RMSSD, ms - is the mean square difference between the duration of adjacent RR intervals, the activity of the parasympathetic link of autonomic regulation;
6. Stress index (SI) - a measure of advantage of the central regulation activity mechanisms over autonomous;
7. Variation coefficient (VC) - total effect of autonomic regulation of blood circulation, total heart rate variability, index of body functional reserve restoration;
8. Autonomic Balance Index (ABI) - indicates the ratio of activity of the sympathetic and parasympathetic parts of the ANS;
9. Rhythm autonomic index (RAI) - integral (secondary) indicator, the smaller the RAI - the more balance is shifted to the parasympathetic side.
In the spectral analysis, HRV distinguishes three main spectral components:
- High Frequency (HF) waves - with a frequency 0,4-0,15 Hz (2,5-6,5 seconds)
- Low Frequency (LF) waves - with a frequency of 0.15-0.04 Hz (6.5-25 sec)
- Very Low Frequency (VLF) waves - with a frequency of 0.04-0.003 Hz (25-333 sec).
For each of the spectral ranges, the absolute total power in the range (Total Power, TP) is calculated. TP is the sum of capacities in the ranges HF, LF and VLF.
According to the spectral analysis of the heart rate, the centralization index was also calculated: CI = (HF + LF) / VLF and the index of vagal-sympathetic interaction LF / HF.
One of the methods for assessing adaptation reactions was to calculate the regulatory systems activity index (RSAI). Based on the analysis of the values of RSAI (expressed in scores from 1 to 10), the following functional states were diagnosed:
1. The state of the optimal (working) voltage of the regulatory systems necessary to maintain an active balance of the organism with the environment (RSAI 1-2 - norm).
2. The state of moderate tension of regulatory systems, when additional functional reserves are needed to adapt the organism to the environmental conditions (RSAI = 3-4).
3. The state of the pronounced voltage of the regulatory systems associated with the active mobilization of protective mechanisms, including the increased activity of the sympatho-adrenal system and the pituitary-adrenal system (RSAI 4-6).
4. The state of strain of the regulatory systems, which is characterized by a lack of protective and adaptive mechanisms, their inability to provide an adequate response of the organism to the influence of environmental factors. Here, excessive activation of regulatory systems is no longer supported by appropriate functional reserves (RSAI 6-7).
5. The state of exhaustion of regulatory systems, in which the activity of control mechanisms is reduced and there are signs of pathology (RSAI 7-8).
6. Failure of adaptation, when specific pathological deviations dominate and the ability of adaptive mechanisms to self-regulate is partially or completely disturbed (RSAI 8-10).
To assess the state of the mother-placenta-fetus system the ultrasound testing with dopplerometry on "Phillips HD11XE" (Austria) in II-III trimesters was carried out. Alongside, the analysis of blood flow velocity curves together with ascertaining of resistance index, pulsation index and systolic-diastolic ratio in uterine arteries, arteries of umbilical cord and middle cerebral artery of the fetus were carried out.
The severity of hemodynamic disorders in uterine, placental and fetal arteries was evaluated involving criteria of M. V. Medvedev (1999) with differentiation of three degrees of complications: 1A - utero-placental blood flow disorders (UPBF), 1B - disruption of feto-placental blood flow (FPBF); II degree - the simultaneous disruption of UPBF and FPBF without reaching critical values; III degree - the critical disruption of FPBF.
The results of the study have been subjected to statistical processing by means of variation statistics, the differences between parameters were evaluated by Student's t-test, considering them significant at p <0.05.
Results. According to the HRV-results the significant decrease of the SDNN and CV levels in pregnant women of the main group (Table 1) was estimated, which indicates the increased activity of central regulation in pregnant women with autonomic dysfunction. Women without identified autonomic disorders were found with predominance of autonomous contour of regulation, for which parasympathetic division of ANS is responsible.
Table 1. Overall level of ANS regulation in the studied pregnant women
Figure Main group Control group P
Med LQ-UQ Med LQ-UQ
SDNN, Msec 29 ± 19 10 - 48 74,5 ± 10,5 64 - 85 p < 0,05
VC, % 6 ± 3 3 - 9 20 ± 6 14 - 26 p < 0,05
TP, Msec2 3976±1128 2848 - 5104 1399±625 774 - 2024 p < 0,05
HRV analysis in pregnant women with autonomic disorders demonstrates SNS hyperactivity, which is presented by higher indicators of MoA and LF (Table 2) in comparison with the control group. Hyperfunction of the sympathetic part was accompanied by the depletion of the compensatory vagal influences, as indicated by the decrease of RMSSD, pNN50 and HF.
HF in women of control group were significantly higher than in the main group - 977,5±177,5 msec2 vs 445,5±131,5 msec2, respectively (p<0.05), which confirms the significant weakening of the influence of a parasympathetic link of ANS on the background of high sympathetic tone in pregnant women of I group.
In the control group CIG- data indicate a tendency to high sympathetic tone with the compensatory growth of the parasympathetic activity, that provides a balanced activity of the ANS.
Table 2. ANS activity in studied groups
Figure Main group Control group P
Activity of SNS
Med LQ-UQ Med LQ-UQ
LF, Msec2 1219,5 ± 248,5 971 - 1468 549,5 ± 190,5 359 - 740 p < 0,05
MoA, % 84,5 ± 18,5 66 - 103 38 ± 8 30 - 46 p < 0,05
Activity of PNS
RMSSD, Msec 13 ± 8 5 - 21 42 ± 7 35 - 49 p < 0,05
pNN50, % 7 ± 7 0 - 14 18 ± 7 11 - 25 p > 0,05
HF, Msec2 445,5 ± 131,5 314 - 577 977,5 ± 177,5 800 - 1155 p < 0,05
Other HRV data that characterize sympathetic-parasympathetic balance, confirm the shift in autonomic balance towards the SNS in patients of the main group. By the results of CIG (Table 3) in
the control group the maintaining of a balance between sympathetic and vagal influences was observed.
Table 3. Sympathetic-parasympathetic balance
Figure Main group Control group P
Med LQ-UQ Med LQ-UQ
LF/HF 3,31 ± 2,49 0,82 - 5,8 3,63 ± 3,31 0,32 - 6,94 p > 0,05
CI 13,76 ± 2,67 11,09 - 16,43 6,03 ± 2,45 3,58 - 8,48 p < 0,05
ABI 413,5 ± 49,5 364 - 463 149 ± 49 100 - 198 p < 0,05
RAI 11 ± 2 9 - 13 6 ± 1 5 - 7 p < 0,05
SI 329 ± 86 243 - 415 92 ± 36 56 - 128 p < 0,05
L/W 7,55 ± 3,07 3 - 13 6 ± 3 3 - 9 p > 0,05
LF characterizes the vascular tone regulation by the SNS. In the majority of control group pregnant - 38 (70,4%) - the value of LF showed normal activity of vascular center (p<0.05). 37 (77,1%) women in group I experienced a dramatic decrease in the activity of the vascular center. Significantly lower levels of LF in women of the main group (Table 4) indicates that gestative restructuring of systemic hemodynamic runs on the background of high sympathetic and low vagal activity.
Table 4. Activity of vascular center
Figure Main group Control group P
Q % Q %
High activity 3 6.2 - - p < 0,05
Normal activity - - 38 70.4 p < 0,05
Low activity 8 16.7 13 24.1 p > 0,05
Sharply impaired activity 37 77.1 3 5.5 p < 0,05
The VLF-component characterizes the activity of the suprasegmental regulation level. The researched VLF values (Table 5) show that only in 11 (22,9%) women of the main group a normal activity of the cardiovascular center is observed, whereas in the control group this figure was found in the vast majority of patients - 46 (85,1%) (p < 0.05).
4 (8,3%) pregnant women of the main group revealed a decrease, and 33 (68,8%) - sharp decrease of subcortical vascular center activity, which gives ground to reason the mental strain and cerebral cortex functional state disturbance in these women.
Table 5. Activity of subcortical cardiovascular center
Figure Main group Control group P
Q % Q %
Normal activity 11 22,9 46 85,2 p < 0,05
Low activity 4 8,3 8 14,8 p > 0,05
Sharply impaired activity 33 68,8 - - p < 0,05
As it can be seen from Table 6, the structure of the regulatory characteristics of the studied women was as follows: normoadaptive condition - in 48 (88,9%) pregnant women of II group and in 15 (31,3%) in patients of the I group, hyperadaptive - in 4 (7,4%) women of the control group and 9 (18,7%) pregnant women of main group, hypoadaptive - in 2 (3,7%) women of group II and 24 (50%) patients with ANS dysfunction.
Table 6. Assessment of the regulatory systems in the studied pregnant women
Figure Main group Control group P
Q % Q %
RSAI 1-3 13 27,1 42 77,8 p<0,05
RSAI 4-5 2 4,2 6 11,1 p>0,05
RSAI 6-7 9 18,7 4 7,4 p>0,05
RSAI 8-10 24 50,0 2 3,7 p<0,05
The analysis of pregnancy in the studied groups revealed, that women of the main group were significantly more often marked with high risk pregnancy than pregnant of control group (Figure 1). So, the risk of miscarriage was diagnosed in 31 (64,5%) patients of the main group and 17 (31,5%) women in the control group. Hypertension disorders were observed in 13 (27,1%) patients of the main group vs 4 (7,4%) cases in the control group. Preterm delivery occurred in 9 (18,8%) pregnant women of the main group vs 3 (5,5%) women in the control group (p<0.05). Premature placental abruption was find out in 2 (4,2%) pregnant women of the main group, while in control group this complication was not noted.
Gestation complications
■ Main group I Control I group
Threatened miscafftiagntal dysfurhiyi|nœrtensive disorfieeîerm df?kieBïbSïire placental abruption
Fig. 1. Pregnancy complications in the studied pregnant women.
Signs of placental dysfunction (Figure 2) were found in 37 (77,1%) pregnant women of the I group and in 19 (35,2%) patients of the control group (p<0,05).
Thus, in 9 (18,8%) pregnant women oligohydramnion was diagnosed, in 30 (62,5%) -different hemodynamic changes, 6 (12,5%) patients had intrauterine growth restriction (IUGR). In group II, signs of placental dysfunction were observed less frequently. In particular, oligohydramnion was noted in 3 (5,5%) patients, maternal-fetus hemodynamic disorders - in 9 (16,7%), IUGR - in 1 (1,9%) pregnant woman.
Fig. 2. The frequency ofplacental dysfunction symptoms in the examined pregnant women
In II-III trimester of pregnancy the dopplerometric indicators deviate from the gestative norms in 30 pregnant women of the main group (62,5%) and 9 women (16.7%) of the control group.
Deviation of UPBF was identified in 13 (27,1%) patients of group I and in 6 (11,1%) patients of the control group (p<0,05). The change in FPBF was noted in 8 (16,7%) of pregnant women in the first group and in 2 (3,7%) women of group II (p<0,05). Associated hemodynamic changes were observed in 5 (13,9%) pregnant women of the main group and 1 (4,5%) women of the control group. The critical blood flow deviations were observed in 3 patients (8.3%) of pregnant women of the main group. In 2 out of 3 women of the main group the fetal distress occurred before 37 weeks. In control group critical blood flow was not found (Table.7).
Table 7. The structure of fetus-placental hemodynamics disorders
Degrees of haemodynamics disorders Main group Control group P
Q % Q %
I A 13 27,1 6 11,1 p < 0,05
I B 8 16,7 2 3,7 p < 0,05
II 6 12,5 1 1,9 p < 0,05
Ill 3 6,2 - - p > 0,05
As evidenced by the data, in pregnant women with violations of autonomic regulation the vascular resistance remains high and practically does not change during gestation. A prolonged decrease of utero-placental perfusion leads to depletion of compensatory abilities of the placental-fetus hemodynamics.
Conclusions. The cardiointervalography is informative for the diagnosis of autonomic regulation disorders, adaptive disorders and changes in hemodynamic responses of the mother-placenta-fetus system.
In pregnant women with autonomic regulation disorders, an increased activity of the central regulatory circuit, high sympathetic function, depletion of compensatory vagal influences, psycho-emotional stress and cerebral cortex functional state violations are noted.
Pregnancy complications such as miscarriage, hypertension disorders, placental dysfunction with hemodynamic disorders and fetal growth retardation are significantly more likely observed in women with detected autonomic dysfunction.
The analysis of heart rate variability in pregnant women will improve the early prediction of gestational pathology, reduce the risk of obstetric and perinatal complications.
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