Regulation Of Heart Rhythm Research Articles

THE RELATIONSHIP OF ANXIETY LEVEL AND REGULATORY PROFILE OF CARDIAC RHYTHM IN MILITARY STUDENTS IN CONDITIONS OF EXAMINATION

The article presents the research results of a regulatory profile of cardiac rhythm in a situation of examination, depending on the level of personal and state anxiety. In order to identify the characteristics of a psychosomatic response to the situation of examination stress the level of anxiety was assessed, which made the basis for ranking groups (low-, moderate-, high - anxious cadets). Cardiac rhythm variability was investigated by the method of R. M. Baevsky, and the statistical and spectral analysis was estimated. The study involved 42 apparently healthy cadets of the first course, 35 girls and 7 boys. The average age was (17.5 ± 0.5) years. A cross-sectional (transverse) study was carried out which protocol included 2 stages: the first stage: anxiety level was determined before the exam, functioning parameters of cardiovascular system and cardiac rhythm variability were registered. The second stage: registration of above mentioned parameters immediately after the examination. The analysis of the research results showed that the level of state anxiety before the exam in all groups was above the level of trait anxiety, which was seen as a natural reaction to the situation of the examination. The reaction of the cardiovascular system and the mechanisms of the autonomic regulation of heart rhythm in a standard situation such as examination were provocative depending on the level of anxiety. Highly anxious examinees showed a higher activation of sympathetic part of autonomic division of nervous system which indicated the generalization of anxiety and possibilities of its somatization.

THE FEATURES OF VEGETATIVE REACTIVITY DURING CONDUCTION OF ORTHOSTATIC TEST IN SPORTSMEN DEPENDING ON THE DIRECTION OF THE TRAINING PROCESS

Objective: to assess the features of initial vegetative tone and vegetative reactivity in sportsmen during their endurance training and speed-power physical exercises. Material and methods. We examined 50 sportsmen (22 athletes и 28 rowers) and 29 young men of the control group. The parameters of heart rate variability were evaluated by the results of ECG registration during conduction of the orthostatic test (complex «Polyspectr»). Results . The initial vegetative tone in speed-power sportsmen is characterized by more expressed activity of autonomic regulation of heart rhythm, and vegetative reactivity is characterized by higher degree of humoral-metabolic regulation mechanisms than in sportsmen specializing in endurance training. Conclusion. The features of the parameters of heart rate variability during the orthostatic test have been determined in dependence on the direction of the training process.

Genetic loci associated with heart rate variability and their effects on cardiac disease risk

Reduced cardiac vagal control reflected in low heart rate variability (HRV) is associated with greater risks for cardiac morbidity and mortality. In two-stage meta-analyses of genome-wide association studies for three HRV traits in up to 53,174 individuals of European ancestry, we detect 17 genome-wide significant SNPs in eight loci. HRV SNPs tag non-synonymous SNPs (in NDUFA11 and KIAA1755), expression quantitative trait loci (eQTLs) (influencing GNG11, RGS6 and NEO1), or are located in genes preferentially expressed in the sinoatrial node (GNG11, RGS6 and HCN4). Genetic risk scores account for 0.9 to 2.6% of the HRV variance. Significant genetic correlation is found for HRV with heart rate (−0.74<rg<−0.55) and blood pressure (−0.35<rg<−0.20). These findings provide clinically relevant biological insight into heritable variation in vagal heart rhythm regulation, with a key role for genetic variants (GNG11, RGS6) that influence G-protein heterotrimer action in GIRK-channel induced pacemaker membrane hyperpolarization.

Combinatorial effect of nicotine and black tea on heart rate variability: Useful or harmful?

The effect of nicotine on heart rate variability (HRV) is controversial. Autonomic nervous system is the main regulator of heart rhythm, and heart rate variability is an appropriate index to assessment of the effects of the autonomic system on heart. In this study, the combination effect of nicotine and black tea consumption on sympatho-vagal balance and heart rate variability was investigated in rats. Male Wistar rats were randomized into four groups as control, tea (2.5g/100cc, daily), nicotine (2mg/kg/d) and tea plus nicotine groups which treated for 28days, and in the 29th day, their electrocardiograms (lead II) were recorded. The mean of high-frequency power (HF) in tea, nicotine and tea plus nicotine groups was significantly more than control group (P<.05), and low-frequency power/high-frequency power (LF/HF) ratio in the nicotine and tea+nicotine groups was significantly less than control group (P<.05). LF values did not differ significantly among groups. Mean of standard deviation of normal RR intervals (SDNN) and square root of the mean squared differences of successive RR intervals (RMSSD) increased significantly in tea, nicotine and tea+nicotine groups in comparison with control group (P<.05) Overall, 4-week administration of black tea, nicotine or their combination with dosages used in this study can increase the heart rate variability and improve the sympatho-vagal balance in rat.

Hjertesvikt med bevart ejeksjonsfraksjon

Half of all heart failure patients have preserved ejection fraction, but there is no established therapy for this patient group. Effective heart failure therapy depends on an understanding of the underlying pathophysiology. This article presents an updated review of knowledge on the causal mechanisms underlying heart failure with preserved ejection fraction (HFpEF). Articles were found by means of a literature search in PubMed. The search combination “heart failure with preserved ejection fraction” OR “HFpEF” OR “diastolic heart failure”) AND (“mechanisms” OR “hypertrophy” OR “inflammation”) yielded 603 hits on 6 April 2017. Relevant articles on causal mechanisms were read in full text. In recent years there has been a paradigm shift with respect to understanding of the pathophysiology of HFpEF. Concentric hypertrophy of the left ventricle with subsequent diastolic dysfunction had long been recognised as an important disease mechanism, but recent research has identified other factors that also contribute to the condition. These include systolic dysfunction, abnormal regulation of heart rhythm, pathological vascular stiffness, autonomic dysfunction and peripheral vasculopathy. Several studies have suggested that comorbidity plays a part by inducing a systemic proinflammatory response which results in multi-organ dysfunction. The pathophysiological picture of HFpEF indicates that the condition resembles a syndrome more than an isolated cardiac disorder. A stronger focus on comorbidity may lead to new diagnostic and therapeutic options.

POSSIBILITIES OF ANXIETY-DEPRESSIVE DISORDERS TREATMENT IN PATIENTS WITH CHRONIC HEART FAILURE

Aim. To study the efficacy and safety of D-, L-gopantenic acid/Pantogam active in the complex treatment of congestive heart failure and coronary heart disease in patients with symptoms of anxiety-depressive disorder. Patients and methods. 82 patients with NYHA II-III heart failure, anxiety and depression were enrolled in the study. Material and methods. The severity of psychological disorders and the efficacy of 8-week therapy with Pantogam active were assessed using Hamilton Depression Rating Scale (HDRS), Hospital Anxiety and Depression Scale (HADS), State Trait Anxiety Index (STAI), and Clinical Global Impression (CGI) Scale. The quality of life was evaluated using the Short Form 36 (SF-36) Health Survey. Global improvement or change of psychological symptoms by CGI Scale were considered as efficacy criteria. Standard diagnostic tools, i.e., echocardiography and 24-hour Holter monitoring, were applied as well. Results. 8-week treatment with Pantogam active of patients with heart failure and depression greatly reduces the severity of anxiety-depressive disorders, improves physical activity tolerance and vegetative regulation of heart rhythm, and decreases heart rate in supraventricular and ventricular arrhythmias. Conclusions. In heart failure patients, anxiety-depressive disorders are accompanied by significant disturbances of heart rhythm vegetative regulation, development of supraventricular and ventricular arrhythmias, physical activity intolerance, increased hospital admission rate, and decreased quality of life. 8-week treatment with Pantogam active due to its bimodal action significantly improves these symptoms and the quality of life.

STATES OF PSYCHOPHYSIOLOGICAL FUNCTIONS OF ELITE ATHLETES IN DIFFERENT AGING GROUPS.

The influences of aging peculiarities in elite athletes on the psychophysiological states on the stage of the maximum capacity were studied. Three groups of athletes with different age were studied. The first group was composed of the athletes aged 18-20, the second one included athletes aged 21-25, the third group included athletes aged 26-34, and were the members of the team of Ukraine in Greco-Roman wrestling. We revealed that elite athletes of older age group were significantly different from the younger by the presence of a large fatigue with the decline of autonomy when forming strategies of sports activities and more perfect the mechanism of autonomic reactions. The aging deterioration of perception of visual information in elite athletes of older age group manifested in a significant decrease of productivity, efficiency and speed for comparison with the groups of younger athletes. Also, in elite athletes older age group there is a significantly higher level of tension of autonomic regulation of heart rhythm compared with young athletes and the presence of more optimal activation of the sympathetic division of the autonomic nervous system.

HEART RATE REGULATION DURING ADAPTATION TO CONDITIONS IN ANTARCTICA.

The article deals with topical issues of the problem of studying the mechanisms of human adaptation to Аntarctic conditions, in particular, the characteristics of the restructuring regulation of cardiovascular system during expedition activity at the Ukrainian Antarctic Station «Academic Vernadsky». The studies were performed directly in Antarctica with the participation of winterers, who during a year were surveyed monthly by cardiointervalography and ECG. As a result of analysis of variance of heart rate in Antarctic conditions we identified the phasic restructuring of the regulation of heart rhythm of winterers. The findings extend the understanding of the peculiarities of realization of regulating the circulatory system during the change of adaptation phases. In particular, the RRNN index has a phasic structure and ranges ± 7-9 c.u. from the beginning of wintering, and in the last phase is increased to -32 c.u. The activity of the development of stress condition among winterers reflects the dynamics of changes in the rate ІNt function, which from the beginning of wintering till January ranged from 2-5 c.u. by modulo, and in the months before the return (February, March), the rate reached 46 c.u. It is established a dominant role of the time factor in influencing the quality adjustment of adaptation processes. While during the first half of the expedition heart rate variability had a balanced regulatory influence, at the end of the expedition an increased activity of the sympathetic division of the autonomic nervous system and stress regulatory mechanisms were observed. This may indicate for incomplete adaptation that requires the application of methods of correction of functional state.

Вплив блокування м1-холінорецепторів асоціативної кори дорослих щурів на автономну регуляцію серцевого ритму при гіпоксичному впливі

&lt;p&gt;Резюме. Моделювання атмосферної гіпоксії в експерименті на щурах дозволяє більш детально дослідити участь речовин медіаторної дії у формуванні адаптації регуляторних систем мозку до гіпоксичного впливу. Метою експерименту було виявити функціональні наслідки блокування м&lt;sub&gt;1&lt;/sub&gt;-холінорецепторів в асоціативній корі дорослих щурів у гіпоксичному середовищі за умов зниженого атмосферного тиску. За умов експериментальної гіпоксії спостерігали функціональну перебудову включення холінергічних структур до механізмів автономного контролю серцевого ритму. Інкубація дорослих щурів у гіпоксичному середовищі за умов зниженого атмосферного тиску, аналогічному природним умовам ІІІ типу погоди, призводить до активації холінергічної регуляції серцевого ритму.&lt;/p&gt;&lt;p&gt; &lt;/p&gt;&lt;p&gt;Ключові слова: блокування м&lt;sub&gt;1&lt;/sub&gt;-холінорецепторів, асоціативна кора, знижений атмосферний тиск.&lt;/p&gt;

Role of beta1-adrenoreceptors at visual associative cortex in rats of different age in the impact on autonomous regulation of the heart rate ander low atmospheric pressure

The role of beta1-adrenoreceptors at visual associative cortex in rats of different age in the impact on autonomous regulation of the heart rate ander low atmospheric pressure was investigated. The aim of the study was to check expediency of application nebivolol to prevent the adverse effects of hypoxic environment, the pressure conditions similar to the third type of weather. Methods. In the experimental group cardiointervalography recorded in the intact condition before hypoxia, after hypoxic exposure, after trepanation of the skull and applying the solution beta1-blocker nebivolol (0.5 mg / kg) through the trepanation hole on the surface of the cerebral cortex (there were separate groups with right-sided and left-sided trepanation in projection of cortical areas Oc2L), with subsequent automatic analysis of data on a personal computer. In the control group a similar procedure of the experiment was carried out excepting hypoxic exposure. Effect of hypoxic atmosphere was created by reducing pressure by 50.76 hPa (0.05 atm) in the Komovsky’s device and hold the anesthetized rat under a glass bell for 1 hour. Results. In juvenile, adult and old intact rats beta1-receptor structures in left and right associative cortical fields Oc2L are included to the neural circuits that provide growth of functional strenuousness in regulation of heart rhythm. After hypoxic exposure beta1-adrenoreceptors in the left field Oc2L are included in other neural circuits, and take part in limiting the functional strenuousness in regulation of heart rhythm. Conclusions. Experimental results about effectiveness of therapeutic doses of beta-1 adrenoblockers especially nebivolol in adult and old age for prevention of unfavorable effects of hypoxic medium that corresponds to the baric conditions of 111type weather are to be verified by the clinical observations

Unraveling of the Effect of Nodose Ganglion Degeneration on the Coronary Artery Vasospasm After Subarachnoid Hemorrhage: An Experimental Study

Cardiac arrest is a major life-threatening complication of subarachnoid hemorrhage (SAH). Although medullary cardiocirculatuar center injury and central sympathetic overactivity have been suspected of initiating coronary artery spasm-induced cardiac arrest, we aimed to elucidate the effects of vagal ischemia at the brainstem on coronary vasospasm and sudden death in SAH. Twenty-six rabbits were randomly divided into 3 groups. Control (n = 5); SHAM (n = 8), and SAH group (n = 13). Experimental SAH was applied by injecting homologous blood into the cisterna magna, and the SHAM group was injected with isotonic saline solution also in the cisterna magna., Twenty-one days after the injection, histopathologic changes of the neuron density of nodose ganglia, the vasospasm index values of the coronary arteries, and the electrocardiographic events were analyzed. Increased vasospasm index of the coronary arteries and degenerated neuron density of nodose ganglion were significantly different between animals with SAH, control, and SHAM groups (P < 0.005). If neurons of the nodose ganglia are lesioned due to ischemic insult during SAH, the heart rhythm regulation by vagus afferent reflexes is disturbed. We found that there is causal relationship between nodose ganglion degeneration and coronary vasospasm. Our finding could be the reason that many cardiac events occur in patients with SAH. Vagal pathway paralysis induced by indirect sympathetic overactivity may trigger coronary vasospasm and heart rhythm disturbances. Our findings will aid in the planning of future experimental studies and in determining the clinical relevance of such studies.

Evaluation and prediction of age-dependent adaptive capabilities in women depending on the initial state of autonomic heart rhythm regulation

This paper studies the specifics of individual emotional experiences in women of average and elderly age depending on the background of autonomic heart regulation, heart rhythm variability (HRV) (vagotonia, normotonia, sympathotonia). Computer pulse diagnostics was used to physiologically monitor the functional state of the subjects during the emotional trial. The internal induction of emotions in vagotonics and sympathotonics caused changes in autonomic balance towards activation of the sympathetic-adrenal level and an increase in the degree of stress on the regulatory systems of an organism, regardless of age. The spectral structure of HRV indicated a transition of rhythm regulation from the autonomic reflex level to the humoral-metabolic level. The functional state of normotensive patients in both age groups was regulated through a quick response system of the HF component. This indicates that persons with signs of autonomic imbalance have lower adaptive capabilities. It is shown that individual differences related to peculiarities of neurohumoral regulation are among the factors that determine the specificity and strength of emotional experience. The results make it possible to explain some of the mechanisms of neurogenic diseases.

Peculiarities of vegetative regulation of heart rate in wrestlers of different age groups

Purpose : the aim of the work was to study the characteristics of vegetative regulation of cardiac rhythm in athletes of high qualification of different age groups. Material : 26 wrestlers of Greco-Roman style of high qualification aged 19-34 years old were studied. Vegetative regulation was assessed by statistical analysis of heart rate variability using cardiac monitors «Polar RS800CX». Results : the results showed that the wrestlers of older age group has a greater level of tension of regulation of heart rhythm for compared with young athletes. This is confirmed by the reduced values of the mean square deviation RR- intervals and triangular index. According to the results of spectral analysis of cardio revealed activation of parasympathetic tone of the autonomic regulation of the heart rhythm of wrestlers in older age group, compared with young athletes. The increase of tension of regulation of heart rate in the wrestlers of older age group accompanied by a slowdown of aperiodic and periodic oscillations of cardio intervals. Conclusions: the high level of tension of regulation of heart rhythm in older wrestlers group (26-34) accompanied by the activation of neurohumoral centers and parasympathetic link of vegetative nervous system.

Functional role of voltage gated Ca(2+) channels in heart automaticity.

Pacemaker activity of automatic cardiac myocytes controls the heartbeat in everyday life. Cardiac automaticity is under the control of several neurotransmitters and hormones and is constantly regulated by the autonomic nervous system to match the physiological needs of the organism. Several classes of ion channels and proteins involved in intracellular Ca2+ dynamics contribute to pacemaker activity. The functional role of voltage-gated calcium channels (VGCCs) in heart automaticity and impulse conduction has been matter of debate for 30 years. However, growing evidence shows that VGCCs are important regulators of the pacemaker mechanisms and play also a major role in atrio-ventricular impulse conduction. Incidentally, studies performed in genetically modified mice lacking L-type Cav1.3 (Cav1.3−/−) or T-type Cav3.1 (Cav3.1−/−) channels show that genetic inactivation of these channels strongly impacts pacemaking. In cardiac pacemaker cells, VGCCs activate at negative voltages at the beginning of the diastolic depolarization and importantly contribute to this phase by supplying inward current. Loss-of-function of these channels also impairs atrio-ventricular conduction. Furthermore, inactivation of Cav1.3 channels promotes also atrial fibrillation and flutter in knockout mice suggesting that these channels can play a role in stabilizing atrial rhythm. Genomic analysis demonstrated that Cav1.3 and Cav3.1 channels are widely expressed in pacemaker tissue of mice, rabbits and humans. Importantly, human diseases of pacemaker activity such as congenital bradycardia and heart block have been attributed to loss-of-function of Cav1.3 and Cav3.1 channels. In this article, we will review the current knowledge on the role of VGCCs in the generation and regulation of heart rate and rhythm. We will discuss also how loss of Ca2+ entry through VGCCs could influence intracellular Ca2+ handling and promote atrial arrhythmias.

The effect of mood disorders on the course of coronary heart disease: a modern model of pathogenesis of depression, pathophysiological and behavioral patterns

The prevalence of depressive disorders at the population level is from 2,5 to 10% among patients with coronary heart disease - 20%. The presence of depressive disorders in patients with coronary artery disease leads to hypersympathicotonia decrease vagal activity, endothelial dysfunction and blood coagulation system, weighing down the disease. The most significant theories of pathophysiological mechanism of increased mortality in patients with cardiovascular disease in combination with mood disorders are increased thrombus formation and disturbance of the autonomic regulation of heart rhythm.

Age- and sex-related changes in heart rate variability under conditions of blockade or stimulation of peripheral adrenoceptor in outbred rats.

Changes in heart rhythm variability were studied in male and female mature and 5-6-week-old rats under conditions of 7-day administration of β1-adrenoreceptor blocker atenolol (2.5 mg/kg) and α1-adrenoreceptor agonist phenylephrine (0.3 mg/kg). Atenolol administration to mature rats was followed by a slight deceleration of cardiac rhythm, a tendency to heart rate variability decrease in the HF range, and moderate increase in centralization of regulation. In 6-week-old rats, increased variability of cardiointervals and significant increase of centralization of the heart rhythm regulation due to an increase in the power of low-frequency waves (specifically VLF) were observed. In both mature and young rats, changes of heart rate frequency and variability in response to atenolol administration were more pronounced in females. Phenylephrine administration was followed by a significant heart rate deceleration, increase in cardiointerval variability and centralization of heart rate regulation in mature rats and by a decrease in heart rate variability in all frequency ranges in 6-week-old rats. In mature rats, changes in heart rate frequency and variability produced by phenylephrine administration were more pronounced in males; in young rats, the most strained heart rhythm developed in females.

ADAPTABILITY OF STUDENTS WITH DIFFERENT INDIVIDUAL AND TYPOLOGICAL PECULIARITIES OF VEGETATIVE FUNCTIONS REGULATION

In the last decade the health of young people inUkraineas well as in many other countries of the world significantly deteriorated according to the results of screening tests. Because of this the main task of prophylactic medicine is development and introduction of new methods of early diagnostics of diseases. The aim of the work to assess the peculiarities of adaptation of students with different types of vegetative regulation.Material and methods: 415 second year students ofLuganskStateMedicalUniversitywere tested. The mechanisms of physiological functions of the body regulation were assessed by registration of cardiac rhythm variability (CRV). Analysis of CRV was performed by three methods: statistical, geometrical, and spectral analysis. The express method proposed by Shlyk, N.I. (2009) was later used to determine the prevailing type of vegetative regulation. To assess adaptability the method of R.M. Baevskij (1979) was used.Results: In the result of investigation 4 types of functional states of regulatory systems were determined: I type – 295 (71 %) of tested, II – in 14 (3 %), III – in 96 (23 %) and IV – only in 10 (2%). I type of functional state of regulatory systems in the wakeful state at rest was characterized by moderate prevalence of central regulation of heart rhythm (MPCR), decreased activity of autonomic regulation. It was noticed that some of the parameters of CRV (like R-R, SDNN, RMSSD and pNN50) which characterize autonomic regulation, were statistically lowere (р≤0.01) compared to type III, and some (like AMo and SI) higher, in both female and male students. Summarized spectrum capacity and components of its wave structure (HF, LF, VLF) which characterize central regulation were statistically significantly lower (р≤0.01) for the I type of regulation compared to the III one which is characterized by moderate prevalence of autonomic regulation of the heart rhythm. In female students with type I autonomic regulation compared to male students such CRV parameters as R-R and AМo were statistically significantly lower (р≤0.05), while the parameters of total potency (TP) and high frequency waves (HF) were higher (р≤0.05), which could point to more centralized heart rhythm regulation in male compared to female. The evaluation of regulatory systems overstress allowed to determine the state of adaptation and risk of overstress or breakdown in students with different types of autonomic regulation.Conclusions: Thus, evaluation of adaptation state in students with different types of autonomic regulation allows to characterize the current functional state and uncover the risk of disease development.

Circadian changes in cardiac rhythm structure in decompensated chronic heart failure.

Circadian changes in heart rhythm structure were studied in rats with decompensated heart failure (experimental group) using the telemetric system for ECG recording and analysis. Analysis of many-day ECG records showed the predominance of various mechanisms of heart rhythm regulation in experimental and control rats throughout 24 h. More severe dysfunction of neuroautonomic mechanisms of regulation in experimental rats was characterized by a circadian dynamics. Many-fold increase in the number of QTc intervals longer than 220 msec and the Tpeak-Tend, most pronounced in experimental animals at night and in the morning, indicated the maximally high risk of fatal ventricular arrhythmias, leading to sudden cardiac death.

Desensitization by Progressive Up-Titration Prevents First-Dose Effects on the Heart: Guinea Pig Study with Ponesimod, a Selective S1P1 Receptor Modulator

Ponesimod, a selective S1P1 receptor modulator, reduces the blood lymphocyte count in all tested species by preventing egress of T and B cells from thymus and peripheral lymphoid organs. In addition, ponesimod transiently affects heart rate and atrioventricular (AV) conduction in humans, effects not observed in mice, rats, and dogs with selective S1P1 receptor modulators, suggesting that the regulation of heart rate and rhythm is species dependent. In the present study, we used conscious guinea pigs implanted with a telemetry device to investigate the effects of single and multiple oral doses of ponesimod on ECG variables, heart rate, and blood pressure. Oral administration of ponesimod did not affect the sinus rate (P rate) but dose-dependently induced AV block type I to III. A single oral dose of 0.1 mg/kg had no effect on ECG variables, while a dose of 3 mg/kg induced AV block type III in all treated guinea pigs. Repeated oral dosing of 1 or 3 mg/kg ponesimod resulted in rapid desensitization, so that the second dose had no or a clearly reduced effect on ECG variables as compared with the first dose. Resensitization of the S1P1 receptor in the heart was concentration dependent. After desensitization had been induced by the first dose of ponesimod, the cardiac system remained desensitized as long as the plasma concentration was ≥75 ng/ml. By using a progressive up-titration regimen, the first-dose effect of ponesimod on heart rate and AV conduction was significantly reduced due to desensitization of the S1P1 receptor. In summary, conscious guinea pigs implanted with a telemetry device represent a useful model to study first-dose effects of S1P1 receptor modulators on heart rate and rhythm. This knowledge was translated to a dosing regimen of ponesimod to be tested in humans to avoid or significantly reduce the first-dose effects.

HEART RATE VARIABILITY AND ENDOTHELIAL FUNCTION IN SUBJECTS WITH HYPERTENSION AND ITS ASSOCIATION WITH CORONARY HEART DISEASE AND TYPE 2 DIABETES MELLITUS

and their relationship to nitric oxide production by endothelium.Design and methods.The study involved 141 patients with hypertension, including isolated hypertension, and associated with coronary heart disease and type 2 diabetes mellitus. Methods of investigation included the evaluation of clinical and conventional instrumentation and laboratory parameters with the additional study of heart rate variability. To assess endothelial function we determined the level of the final stable metabolites of nitric oxide: nitrite and nitrate anions (NO2 - and NO3 -) in blood plasma. Results and conclusions.According to the analysis of heart rate variability we found apparent disturbances of heart rhythm regulation in hypertensive patients: decreased overall heart rate variability, decreased amplitude of parasympathetic, sympathetic and humoral waves, reduced proportion of sympathetic, parasympathetic waves and increase of humoral waves. Co-existing diabetes mellitus led to more apparent disturbances of autonomic regulation of heart rhythm. High heart rate and low heart rate variability in hypertensive patients are associated with an increase of the final metabolites of nitric oxide in the blood plasma.